DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

Welcome to our TEA & BISCUIT ARTICLES

THE HEIGHT VELOCITY DIAGRAM:

As it is ‘World Helicopter Day’ today Sunday 15th August 2021, I thought I would cover a flight safety subject to mark the occasion.
This is another short post as I know your thoughts will be on getting airborne to celebrate the day and making the most of this current spell of reasonable weather, rather than drinking tea.
There is always a good discussion to be had with pilots on the subject of the Height Velocity (HV) Diagram, also known as the ‘dead man’s curve’. Of course, it can kill lady pilots too but it’s not considered ‘good form’ to discus such (I’m looking forward to the interesting responses)!
When talking to pilots about the make up and conditions under which the diagram/curve is formed,
I usually ask if the HV diagram is also valid during the approach.
The vast majority will say ‘yes’ and that the shaded avoid areas should be avoided on both departure and approach.
This always causes me to mentally reprimand myself as I have clearly failed to get across the conditions required in which the HV diagram is constructed in a manner that has allowed the pilots to understand.
To me that’s more of an instructional failure than the inability of the pilots to understand what I have just explained.
The HV diagram is a performance chart and so hence it is to be found in the performance section of the relevant flight manual/pilots operating handbook.
It is not a limitation.
In the days of long hot summers and crispy bacon, the HV diagram was used as a selling point for the aircraft; the smaller the shaded area, the safer the aircraft.
However, it is not so now.
FAR PART 27.79 Limiting height-speed envelope
If there is any combination of height and forward speed (including hover) under which a safe landing cannot be made then a limiting height speed envelope must be established.

(1) ALTITUDE – from standard sea level conditions to the maximum altitude capability of the rotorcraft or 7000 feet, whichever is less.

(2) WEIGHT – from the maximum weight (at sea level) to the lesser weight selected by the applicant for each altitude covered by par (a)(1) of this section.
‘It’s a graphical depiction that indicates to the pilot ‘unsafe flight conditions’
So simply, it is looking at the areas of stored energy available should the engine stop providing that energy (fail), being; kinetic (RRPM and Airspeed) and potential (height above the ground) and their corresponding amounts.
It is developed with the ‘average pilots’ in mind and what would be their intervention time to a sudden engine failure in the low speed, low level operational areas of flight.
The conditions are:

Wind speed – less than 2kts – usually carried out early morning.

Weight- max gross -1% to + 5%

Minimum crew Minimum instrument panel

No damage to aircraft after landing

The development of the HV diagram is usually the last part of the certification program as the flying required is by its nature likely to end up damaging the test platforms.
Those pilots that have attended the RHC factory flight safety course or my flight safety course will have seen the videos of the exploration of the HV diagram from the original R22 test flights through to the R66.
The factory test pilot at the beginning of the R22 certification program, and through to the R44 program, was an incredible chap; Bob Golden.
I was lucky to fly with Bob on many occasions and he was an outstanding pilot in every sense.
Bob was sadly taken by cancer but if you ever watch the R22/R44/R66 test flight video then you will hear Frank Robinson complement him on his flying saying “That’s perfect Bob”.
So, as long as you know who Bob was in the video then Bob lives on, especially on World Helicopter Day.
There are three (3) shaded avoid areas required by current certification requirements; low speed v height at max gross weight at sea level and a lower weight at altitude, with the third being the high speed v height.
In the hot summer, crispy bacon days there were only two (2) shaded areas; low speed v height at gross weight and high speed v height (requirements of certification at the time)
The main points of the example HV diagram found below:

The low hover point – Green 10ft/0kts, no flare no time delay, normal pilot reaction time. Collective cannot be lowered and hard surface/soft surface.

The knee of the curve – Red 150 ft / 50 kts. From the ‘low hover’ point to the ‘knee of the curve’ is conducted at ‘take-off’ power with no delay.

The high hover point – Blue 400 ft/ 0 kts, Stabilized OGE hover, vertical speed near zero, 1 sec delay prior to lowering collective and a reasonable dive angle, 10º – 20º max nose down

The High hover point at a lesser weight at altitude – Yellow 600 ft/ 0 kts, Stabilized OGE hover, vertical speed near zero, 1 sec delay prior to lowering collective and a reasonable dive angle, 10º – 20º max nose down

The high speed portion – Cyan Normal pilot reaction time. Power as required for level flight, no delay.



Where the graph goes from the ‘knee of the curve’ back to the high hover points, the condition of flight is ‘power as required’ to maintain level flight at the height and KIAS being developed, with a one second delay before the pilot can react.
The one (1) second delay before the test pilot can react to the simulated engine failure (throttle chop) is to account for the average pilots reaction time.
The point on the HV diagram being developed has to be validated/ratified by the designated test pilot of the authority responsible for the aircraft certification before it can be used as a point to produce the diagram.
So with the above short venture into the conditions required to develop an HV diagram, you can hopefully see that the answer to the question of “does it apply on approach?” is NO due to the following:

On approach: There is less power being demanded. There is less pitch angle, angle of attack.

There will be a rate of descent, so an induced flow up through the disc, against departure where the induced flow is predominantly down through the disc.

Weight, wind speed, weight etc, etc might not be as required during the development of the HV diagram.

In short, the diagram is developed under strict conditions involving hover height, take off power, cruise flight conditions and not during approach power or conditions.

Have a great World Helicopter Day.

Knowledge is flight safety helping to keep your RPM in the green.

R

This is ‘A Tea & Biscuit Production’ ® 

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

Welcome to our TEA & BISCUIT ARTICLES

CARBURETTOR ICING REMINDER:

I have come to realise that by encouraging you to consume large quantities of tea, cake and biscuits, I have most probably been unwittingly reducing the pilot’s available power, by increasing the helicopter’s takeoff weight; this could be construed as ‘negative training’!
So time for a glass of chilled mineral water, with a handful of almonds and some dried apricots.
Alternatively, if you are an insomniac, read this article in bed as my wife ensures me that it is guaranteed to send you to sleep!
This time of year it’s ‘weather, weather, weather’ as this remains one of the consistent causes of helicopter fatal accidents.
Firstly, a quick reminder that the real danger the pilot faces is not bumping into big white fluffy clouds but degrading visual conditions.
As the conditions deteriorate there will be a natural increase in the pilot’s workload, leading to the brain shutting down some of the senses it considers to be unnecessary for the given workload.
One such action is the reduction of the pilot’s peripheral vision to the point of tunnel vision. The result of this is that the pilot misses the all important degrading visual cues as they become ever more focused on trying to remain visually in contact with the ground.
Spacial disorientation, and the ensuing loss of control due to the the inherent instability of the helicopter, will happen very quickly once all visual references are lost, resulting in a fatal accident.
It’s simple.
If you are thinking about whether to go or not then choose “NOT”!
Remember that there is always another day but only if you are still around to enjoy it.
In approximately 2 months time we will be into year 10 of NO fatal accidents involving the Robinson product within the UK.
I put this down to the dedication and training standards of the instructors, the very high standard of maintenance, and the increasing realisation of pilots that they are actually mortal and they do leave behind wrecked and grief stricken families; which also includes their passengers and their respective families.
So I thank you all for keeping me unemployed in my job as an RHC accident investigator. Please keep up the brilliant work.
As the time of dank, dull days have arrived it means that the conditions conducive to carburettor icing increase quite significantly.
With that in mind, I thought it might be a good idea to refresh the old grey matter in the ways to help with avoiding carburettor icing.
I am just going to cover a few key points in this post as the document that I published many years ago about carburettor icing, and is still very relevant today, is a free download on my website: www.morningtonsanfordaviation.com
The first thing to understand is that when Lycoming state that carburettor icing is negligible at takeoff power they are referring to their engines fitted into fixed wing, where takeoff power tends to be full throttle, meaning that the butterfly valve is 90 degrees ish, depending on engine type, so it is inline (fully open) with the airflow.
So I would agree that, in this condition, the chances of carburettor icing are indeed negligible.
However, the piston engines fitted into the Robinson helicopter have all been de-rated by some degree; therefore, there has to be a very good understanding that if you are flying an R22 or R44 type with a carburettor, then your takeoff power is not such that the butterfly valve is fully open!
Furthermore, the greater the engine de-rating, the further the butterfly valve is away from fully open at takeoff power.
So for example, the R22BII being de-rated from 180BHP to 131BHP and 124BHP, is more de-rated than the R22B, which is de-rated from 160BHP to 131BHP and 124BHP.
Therefore, the butterfly valve in the carburettor of a Beta II is nowhere close to fully open at takeoff power!
The graph below, (bottom of post) taken from one of my carburettor icing presentations, depicts the butterfly valve angle v manifold pressure for the R22B (blue dot), R22BII (red dot) and R44 A/R/RI (green dot) at + 15deg C at sea level conditions
As we can see, the butterfly valve angle for the R22B at takeoff and maximum continuous power (MCP) is circa 54 and 51 degrees respectively.
The R22BII at takeoff power and MCP is circa 50 and 47 degrees respectively.
So you can see from this information that the R22BII is potentially more prone to carburettor icing than the R22B, purely due to the greater de-rating reducing the butterfly valve angle.



The R44 A/R/RI certainly has the potential to be susceptible to carburettor icing but seems to be less so than the the R22 for several possible reasons; butterfly angles are greater at takeoff power and MCP and the engine is cowled in, giving the potential of heat soak.
So some preventive measures the pilot can take to reduce the likelihood of encountering carburettor icing are as follows:

• Refresh your memory of RHC safety notices, numbers: 25 and 31,

• Read my ‘No ice, thank you’ document available as a free download on my website www.morningtonsanfordaviation.com

• Gain as much information as possible relating to the prevailing weather conditions, so dew point v outside air temperature (OAT).

The closer they are together the more the likelihood of carburettor icing.

• During your pre-flight check (first of the day) check the carburettor air temperature gauge against the OAT gauge.

They should both be reading the same temperature.

• When checking the carburettor heat system, observe the effect of the hot air being introduced into the induction system on the RPM.
If there is a drop in RPM, followed by an increase in RPM, you have just observed a positive indication of carburettor icing; the heat has cleared the ice which had built up whilst waiting for the clutch light to go out and the result of the removed ice is that the engine has become more efficient, hence the RPM increase.
If there is a drop in RPM and there is no subsequent increase, then you have just observed a positive indication that there has been no ice build up in the carburettor.
These simple checks can allow the pilot to ascertain the likelihood of encountering carburettor icing during the intended flight… increasing their awareness.
As they say ‘praemonitus praemunitus’ or ‘forewarned is forearmed’!
Due to the UK’s daily average humidity levels and temperature range, the potential for carburettor icing is a daily threat, which means the pilot should be well versed in the subject and should have been well taught in the correct use of carburettor heat in flight.
The pilot must understand that carb’ heat must be applied during takeoff and in fact during all phases of flight.
So, if this is the case, then the carb’ heat temperature gauge is a very important instrument. Therefore, the instrument must be checked for accuracy prior to the first flight of every day! As a pilot, you will not be the first or the last pilot who has got themselves into a stressful situation due to an inaccurate carb’ heat temperature gauge.
The relevant POH gives information on the amount of carburettor heat that should be applied.
All I will say is that due to the UK’s general atmospheric conditions, which makes it conducive to carburettor icing, the pilot should err on the side of caution and use more than stated.
I have covered the subject of engine limitations in a previous post which I hope cleared up the misunderstanding of what the engine limit is; the limit being a BHP limit, which means that the manifold pressure limit placard is not always going to be the actual limit.
Again I reiterate, read my ‘No ice thank you’ document and RHC SN number 37 for further guidance.
My personal opinion, which come from a lot of past inflight carburettor icing testing, is that the pilot must pull full carb’ heat at least 20 seconds prior to any substantial reduction in power.
This is a ‘last chance’ action, to make sure there is definitely no ice in the carburettor before the butterfly valve angle is reduced.
Finally, the use of carburettor heat on an approach; it should be selected fully hot to about 200ft AGL, at which point it should be placed back into the pre selected position that you had for the flight, not fully cold.
This would also apply to confined area approaches, which, therefore must mean that the pilot must conduct the power check with the carb’ heat in the pre selected position; which is keeping the needle out of the yellow (the requirement in the POH) and not selected cold!!! The caveat to this would be subject to your density altitude.
I know that a lot of pilots out there throw their hands in the air and state that they cannot believe in this day and age we still have carburettor icing issues.
Well, I have been involved with a project for many years which I believe is an answer to the problem.
I hope the project will see a modification of the carburettor (before I retire) that will significantly reduce the accidents caused by carburettor icing both in helicopters and fixed wing. 

Knowledge is flight safety helping to keep your RPM in the green.

R

This is ‘A Tea & Biscuit Production’ ® 

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

Welcome to our TEA & BISCUIT ARTICLES

RHC SAFETY ALERT:

Time for a rather quick Tea & Biscuit! I hope that R22 & R44 pilots are already aware that RHC have issued a safety alert with regard to the pilot monitoring the engine governor on the R22 and R44 series aircraft.
I have said many times before that the governor has, for most pilots, become THE primary engine throttle control, which is reinforced by the majority of the flight training environment that gives student pilots very little ‘governor off’ training.
The pilot needs to understand that the governor is there to assist the pilot.
The pilot has the primary responsibility for the engine throttle system and therefore is responsible for controlling the engine RPM and rotor RPM.
It is a fact that pilots who have been taught to fly the R22 and R44 series aircraft since the governor was fitted are less RPM aware than those pilots who learnt during pre governor days.
Or should I say “In the days of crispy bacon and long hot summers”?
Given the safety alert, the R22 and R44 pilot might like to refresh their RPM governor knowledge by reading the POH at 7-6 and note that it states “The governor is designed to assist in controlling the RPM under normal conditions”.
Yes, I know that the POH at 2-5 states that “flight is prohibited with the governor selected off, with the exceptions for in-flight system malfunction or emergency procedures training”. And it is this text that is used as an excuse not to conduct governor off training.
Well, if we go to the POH at 3-7, we will find an emergency procedure for the RPM governor malfunctions!
If we then go to 3-11 there is an emergency procedure for the recovery of Low RPM.
How does the instructor teach these emergency procedures to any level of competency without giving the student sufficient governor off training?
This can be conducted under the point “with the exceptions for in-flight system malfunction or emergency procedures training” in the POH 2-5 referenced above.
Until we give the student pilot sufficient RPM governor off training, we will continue to have engine/rotor RPM issues.
Of course, in the past most of these RPM excursions from 104% or 102% were never reported, but now the R22 and R44 EMU will record such excursions and therefore we are going to see far more reported over speeds or under speeds in the future.
The lack of pilot monitoring of the engine governor is a symptom, as is the pilot’s lack of RPM awareness.
The cause is insufficient governor off training! 

Knowledge is flight safety helping to keep your RPM in the green.

R

This is ‘A Tea & Biscuit Production’ ® 

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

Welcome to our TEA & BISCUIT ARTICLES

GREAT BRITAIN’S 10 YEAR ANNIVERSARY-NO ROBINSON TYPE FATAL ACCIDENTS:

It is 11:27 on 6th January 2022!
Definitely time for tea & biscuits on this auspicious day!
A very Happy New Year and huge congratulations must go to the Robinson helicopter fraternity in Great Britain (GB) for safely taking us to the 10 year mark without a Robinson Helicopter fatal accident.
There will be many reasons for this success but I would like to give credit to the quality and dedication of the engineers and staff that maintain the fleet.
The pilots, operators, flying schools and their staff and of course the high standard of flight instruction given by our flight instructors.
You are setting a fine example on how to operate the Robinson helicopter safely and in doing so are going a long way in proving my long held view that the Robinson product is not an inherently unsafe aircraft as some would have us believe.
However, do not relax as this is just the first milestone.
The hardest part of flight safety is to maintain the fatal accident rate at zero in the coming years; it is all too easy to relax thinking that we have solved the problem as we have not!
For example, we have a continuing number of new pilots joining our helicopter world and they will all need sound advice and guidance as they build their hours and experience.
And of course, one of our biggest dangers is ‘complacency’.
In GB, apart from the obvious flight training aspect, the Robinson product is used very much as a back garden to back garden mode of transport, which requires a great amount of self discipline from the pilot in their decision making, particularly when it comes to determining acceptable weather conditions.
As we are all aware, this lovely wet and windy rock we live on has some very challenging flying conditions, ‘weather’ in particular.
However, we have proved that if you operate the aircraft within its limits, take and understand the advice given by RHC on critical flight conditions, listen and take note of flight safety information disseminated on a regular basis, and make the right decision, then the Robinson Product is as safe as any other helicopter.
Perhaps one of the messages that we are putting across and is now being understood by the pilot, is that most accidents could have been prevented prior to takeoff!
It’s bad decision making that becomes the first link in the chain of events leading to an accident.
I was involved in the investigation of the very first R22 fatal accident in GB back on 28th March 1990; the R22 struck the top of trees on rising ground which were cloud covered at the time.
I have been involved in the investigations from 1990 right through to the (to date) last Robinson helicopter fatal accident on 6th January 2012 at 11:26.
Perhaps this was a Robinson helicopter epiphany moment; a sudden intuitive perception of or insight into the reality or meaning of something initiated by an occurrence or experience, coincidentally on the day that we celebrate the actual Epiphany.
Accident Investigation has been a double edged sword.
One side being the difficult aspect that the helicopter industry is very small, which meant that I would usually know the victims involved and, in some cases, might have been involved with their flight training.
The other being the opportunity Frank Robinson gave me to represent him; thus enabling me to enhance my knowledge of his product and further my passion for flight safety and the prevention of accidents.
Although the accident rate seemed relentless I was always sanguine about the future as I firmly believed that improving the pilot knowledge (during and post training) of the product systems, their critical flight conditions, their avoidance and the types and causes of accidents was an area that, if relentlessly pursued, would make a considerable difference to the accident rates in the future.
And as I have said before and I will keep harping on “Most accidents could have been prevented prior to takeoff”.
One of the most difficult aspects of being Frank’s man on the ground was the call I had to make to Frank to inform him of a fatal event.
Frank took these accidents very, very personally and anybody out there who is under the misguided idea/opinion that the Robinson Helicopter Company does not care when one of their products is involved in a fatal accident is either delusional or has been brain washed by the proliferation of associated vultures attracted by the accident.
I can tell you from very personal experience (not hearsay or assumptions) that it could not be further from the truth; Frank was tireless in his pursuit of flight safety and the prevention of accidents, as are all at RHC.
So now might be a good time to reinforce my long standing view which I have held since 1980, that the R22, R44 and R66 types are inherently safe and their tarnished reputation is more to do with issues of the lack of pilot knowledge, skill set and poor decision making/captaincy than any implied inherent design issue with the product.
As the saying goes… “A poor workman always blames his tools”.
For example, right from the early 1980’s it has been relentlessly argued by some that the Robinson Helicopter fatal accidents are due to a flawed product design.
In particular it was, and still is to this day, primarily aimed at the main rotor system which is said to be ‘inherently unstable’.
In my humble view, if this is the case, then why has it not been a world wide issue rather than what seems to be local ‘hot spots’?
With thousands of hours in the Robinson product, from flight instruction to air testing etc. why am I still alive?
Some of the arguments put forward by various bodies over the years to try and argue the point that there is a design fault with the Robinson product are:

• “The helicopter broke up in flight”. Usually based on evidence conducive to a main rotor blade to tail cone or cabin contact issue.
Well, that may have happened but for the main rotor blade to diverge from its normal path of rotation the pilot has to make it happen!
The main rotor to tail cone or cabin contact is a symptom and not the cause; the pilot had for some reason lost control of the aircraft prior to the break up.
For example, allowing the rotor RPM to decay to the point of Low RPM Rotor Stall, putting the helicopter into a ‘low-G’ situation or excessive control inputs/over controlling.

• “The fatal accident occurred even with a flight instructor onboard”.
Flight training inherently carries more risk of accidents and unfortunately the risk applies to all training platforms but a training platform that became the world’s most popular helicopter type will statistically be seen to have more accidents due to numbers.

• “The fatal accident occurred with a very experienced flight instructor onboard”. Well, what is meant by ‘experienced’?
When you look at what was/is considered to count as ‘experienced’ you find that the so called experienced flight instructor would likely be a high time aeroplane flight instructor with a few hours rotary hours as an add on to their instructor ratings.
Most probably the worst type of instructor teaching in any two (2) bladed helicopter.
They are used to flying docile stable platforms, where interaction times are much greater and of course the real danger is the reaction to a low RRPM audible caution and light activation.
This would invoke a simple human factor issue; a ‘revert to predominant type reaction’ to a stall warning, likely causing the instructor to push the nose down and subsequently inadvertently expose the aircraft to low-G.
Not my idea of an ‘experienced flight instructor’ in relation to flying a helicopter, which are inherently unstable, and in particular, a two (2) bladed light sensitive R22 platform.

• “The fatal accident occurred with a very experienced helicopter flight instructor onboard”. Well again, what is meant by ‘experienced’
The instructor might have been a very experienced helicopter flight instructor but on which type of platform?
Some of the instructors on board at the time of these accidents were ex military, ex Vietnam pilots, used to flying heavy docile high inertia military platforms or the Bell 47, Bell 206 or the Hiller.
Again, docile platforms with high inertia rotor systems.
Not my idea of an ‘experienced flight instructor’ in relation to flying a low inertia, two (2) bladed, light, sensitive R22 platform.
What the few examples above seem to indicate to me is that the pilot/instructor experience given is not always what it seems to be.
That it is probable that there was a lot more ‘human factors’ at play than may have been taken into account during the subsequent investigation.

• High time fix-wing instructors reverting to predominant training…pushing the nose down as an instinctive reaction to a low RRPM caution and exposing the aircraft to low-G.

• Hight time rotary instructors, whose experience is in high inertia, docile, platforms, where they have more interaction time to correct inflight issues, are very likely to be much slower in their reactions and correcting a students control input errors.
For example: With the R22’s low main rotor inertia and reasonably high main rotor RPM, if the instructor is slow to react to low RRPM issues, or allows the student to put a large forward cyclic control input, thing can happen very quickly, within 2 to 3 main rotor blade orbits, which occur within circa half a second!
However, if the instructor is aware that for example in the case of the R22, that the most amount of stored kinetic energy they can use to recover a low RRPM situation is in their airspeed and the great benefit of a low inertia rotor system is that the positive effect of transferring (flare) this stored energy into the main rotor system is instantaneous, it would assist in the prevention of Low RPM Rotor Stall.
It’s like turning on an energy tap!

• It is possible that the accident pilot/instructor was flying the aircraft based on the natural tendency to fly and react too inflight issues in accordance with (IAW) their predominant type, which was not the Robinson helicopter.
All helicopter types have their areas that bite; it does not make them unsafe.
Just that the instructor/pilot, must be well versed in them and actively guard against them. My view has always been that the R22 is a very safe and an exceedingly good training platform.
It has sensitive, light handling qualities.
It requires light sensitive control inputs, a good level of awareness, with quicker intervention times required, which culminate in the production of a very rounded less complacent pilot to the point that, generally speaking, if you can fly the R22 well, then you can fly any helicopter well.
However, this does not work the other way around!
A pilot, and in particular a flight instructor, coming from a docile, high inertia rotor type will find it initially difficult to adapt to the R22’s sensitivity and the tendency for things to happen a bit quicker.
From an instructor point of view, I would agree that the R22 suffers fools, far less gladly, than other helicopter types.
There is an exceedingly good example of the issues flight instructors can find themselves with when training on different platform types.
This example happened in GB during the early 1990’s when very experienced helicopter instructors unwittingly encountered just such a situation; flying to predominant type and not actual type.
A very well known helicopter operator/flying school changed their training platform from the Bell 47 to the R22.
As the school started to build the training hours it became apparent that they were suffering from a number of small incidents with the R22 that had not been previously encountered with the Bell 47.
Being the very professional flying school that they were, the school principal and the flight instructors discussed the issues and came to the conclusion that the problem probably stemmed from the instructors handling the R22 as if it was a Bell 47.
They needed to take into account the fact that they had changed their training platform from a relatively docile, high inertia platform on which they had a lot of experience to a very sensitive low inertia platform on which they had a lot less experience.
The issues were resolved by knowledgeable professional instructors willing to look at all possible reasons, including their instructional technique, rather than just blaming the helicopter type.
It is all to easy just to blame the Robinson product for the accident, which is reinforced by the vultures who circle an accident site waiting for their chance to make money out of the misfortunes of others.
The media will rollout their reporters, who seem to suddenly become aviation experts and accident investigators overnight, and churn out articles that can be egregious in their content with headlines such as “Danger spins from the sky” containing what I can only describe as sensationalised misinformation.
We add to this a proliferation of internet warriors who seem to know the cause of the accident even before the accident investigator arrives onsite.
This is just simply ‘trial by media’ which has the ability to detrimentally affect any product and hinders the actual search for the truth.
As the saying goes, innocent or not, “Mud sticks”!
The mud can stick to such an extent that New Zealand (NZ), a country that operates and has an industry that relies heavily on the Robinson product, particularly the R44, initially put the type on a ‘watch list’.
Following a non fatal accident where an R44 allegedly clipped a tree and caused the media to dig up a previous training flight that suffered from a low-G event, the NZ Department of Conservation (DOC) then stopped using Robinson Helicopters to transport their staff because of safety concerns with the Robinson product.
Other departments and councils then followed suit.
One of their main issues seems to be with a high percentage of low-G accidents.
There are well documented statistics on the product accident rates published by the local authorities and it is not my intention to drag these out again but to try and understand why NZ has a problem with one particular critical flight condition: low-G.
I am very conscious of the fact that although I have had the great pleasure of visiting NZ I have not flown a helicopter in that environment and so this leaves me lacking in any sort of experience associated with operating in this particular country.
I know that it has been argued that the particularly hostile mountainous regions, with it’s associated windy conditions, requires a special type of helicopter pilot.
However, I do not accept this as a valid argument as there are plenty of places around the world that have equally hostile environments, if not worse than NZ.
My view is that poor captaincy and their psyche is probably at the heart of the problems being experienced.
For example, this is a country where, despite the fact that an FAA Airworthiness Directive prohibiting the demonstration of low-G has been in force for many years, allegedly has instructors who still teach the student pilot this critical flight condition up to the point of the uncommanded right roll; just as we did in the days of crispy bacon and long hot summers. Problem.
At this point the student pilot will have to make a counter instinctive control input to correct the uncommanded right roll (with aft cyclic and not the instinctive left cyclic control input) which can be at a rate of 100 deg a second accelerating!
They are teaching a critical flight condition to the point that requires a counter instinctive control input from the pilot rather than a conventional control input.
The very possible negative result of this training is the danger that the future pilot will not consider the situation dangerous and respond to a low-G situation until they feel the right roll, which of course is too late.
Do these alleged instructors really think that the pilot who is experiencing elevated stress levels in turbulence for example, is really going to be able to instinctively correct an uncommanded right roll with an aft cyclic control input?
No.
They will instinctively apply opposite left cyclic at the same rate as the right roll and the result…a low-G fatal accident! Why?
Human factors!
Any time a pilot finds themselves in a situation that take them outside of their comfort zone, it inevitably leads to high pilot workload and with that comes the corresponding stress.
As the situation becomes more difficult, the pilot’s brain, and in particular the limbic system region, will perceive this as a threat and trigger the release of steroid hormones including adrenalin and the primary stress hormone cortisol, which marshals systems throughout the body to deal with the threat; increasing heart rate, blood pressure and blood flow etc. Neurotransmitters are also released that will suppress (shut down) activity in areas at the front of the brain concerned with concentration, rational thought, short term memory and inhibition, thereby hindering the ability of the person to handle complex social or intellectual tasks and behaviours.
These mental events were critical in primitive times to allow the person to react quickly to the threat; the fight or flight response.
The pilot has no control over these mental events!
In short, the pilot will find that as the stress reaction to the threat evolves, even simple tasks that they could carry out easily before the threat/stress occurred, become difficult if not impossible to perform.
The pilot’s situational awareness, verbal functioning, mental capacity, auditory functions etc. will be reduced and they will swiftly become overwhelmed by events, leading to a loss of control of the situation.
There may also be an element of surprise such as a sudden encounter with turbulence when flying in a hilly or mountainous region; this can cause the pilot to suffer from the ‘startle effect’.
The ’startle effect’ has the following effects on the pilot’s physical and mental responses:

• The physical effect (uncontrolled/automatic instant reflex) which means that the pilot can unwittingly induce large negative control inputs or even freeze on the controls.
Sir Sterling Moss famously said: “Calling on my years of experience, I froze at the controls”.
I am sure that at some point in our lives we have all sat in the cinema and jumped out of our skin when we have been startled by an event on the screen, often resulting in our popcorn being thrown over the people sitting close by!
That is a physical uncontrolled/automatic instant reflex.

• The mental effect disrupts cognitive processing which can negatively influence the pilot’s decision making and problem solving abilities; it is very easy for the pilot to become over whelmed by the intense physiological responses.
These responses have the following effects: Increase in heart rate and blood pressure. Breathing increases in both rate and depth.
The liver releases additional sugar and the adrenal glands release adrenalin.
Muscles tense – as an example, a caution I keep referring to when flying a Robinson product is that this will cause the pilot to unwittingly over ride the engine governor, so obtain plenty of manual throttle manipulation time to improve your manual throttle skill set.
The pilot will sweat Brain activity is negatively effected as reactions will become more instinctive and less reasoned.
It has been found that the recovery from the mental aspect of the ’startle’ can take some 30 seconds after the event occurs and this will depend on the complexity of the task/s in hand. So the pilot’s cognitive processing is disrupted thereby making problem solving and decision making very difficult, if not impossible.
The end result is that the pilot is just unable to react in a timely manner to the event and the accident happens or the pilot reacts in a negative way with the same outcome.
I’m afraid, the brain sitting in the dark is not going to allow the clarity of thought or sufficient time to enable the pilot to make a counter instinctive control input, even to save their life! Are these high incidents of low-G possibly a direct result of the instructor allegedly teaching a pilot to only react to a critical flight condition at the point it is happening?
Pure ‘human factors’ will prevent the pilot from successfully recovering.
They should be teaching the pilot to react/recover at a much earlier incipient stage, where pilot stress levels are much lower, with less chance of being ‘overwhelmed by events’.
A very early incipient stage of low-G for example is the slightly weightless feeling you get in your stomach when going over a hump back bridge.
If the pilot, when experiencing the slightly light on the seat sensation during turbulence, just reloads the disc by applying aft cyclic control input, then their possible exposure to a low-G condition is greatly reduced.
Added to this training must be the understanding that when encountering turbulence the pilot should immediately slow down.
This is for a number of very good reasons:
• The uncommanded right roll couple is caused by the aircraft attitude putting the tail rotor anti-torque thrust above the aircraft centre of gravity (C of G) causing a rolling couple in the direction of the tail rotor thrust vector (to the right) and the further the thrust vector is above the C of G, the greater the rolling couple.
So, slowing down will change the attitude of the aircraft such that it will reduce the rolling couple by bringing the tail rotor anti torque thrust down to a point more in line with the C of G.

• The more tail rotor thrust being produced, the smaller the couple has to be to initiate an uncommanded right roll, and the quicker the aircraft will roll.
By slowing down, the pilot will also be reducing the power demand, which reduces the anti torque thrust being produced by the tail rotor, thus reducing the possibility of the uncommanded right roll.

• The aircraft handling becomes more manageable at a slower speed; aircraft responses to flight control inputs happen less quickly, which helps reduce the tendency to over control, thus reducing the workload and the associated increase in pilot stress levels.

• Finally, the student should be taught that they should fly out of the turbulent area, or if this is not possible, they should land.
As with most inflight emergencies, the safest place is usually right below you…on the ground!
Do these same instructors teach other critical flight conditions up to the cusp of the event rather than just to the early incipient stages?
A moot question when such drastic actions are taken against a helicopter type, when the extent of the problem seems to be localised and flight instructors are allegedly ignoring an FAA Airworthiness Directive, the aircraft limitations and teaching the critical flight condition low-G up to a possibly unrecoverable point as argued above.
Which just so happens to be the very issue that has caused the safety issues, which have basically lead to the grounding the aircraft type in NZ!
It is my understanding that the fatal accident that culminated in effectively grounding the aircraft type due to perceived safety issues was involved in flight training at the time.
My knowledge of the accident is no more and no less than that gained from the very comprehensive accident report issued on 19th February 2015 by the Transport Accident Investigation Commission (TAIC) in New Zealand.
I am sure that the document has been sifted through with a very fine tooth comb by all of the interested parties, of which I am not one of them, other than someone interested in looking at flight safety and accident prevention.
In my humble view, the underlying problem is one of flight training rather than an inherent design problem with the type as some people are advocating.
In fact the report covers a number of flight training issues and gives some very positive recommended changes, which are all very encouraging.
Below are some of my general thoughts regarding the training aspect of the accident flight that come to mind reading the referenced report:

• The accident training flight is described as ‘ad hoc’.
I’m not sure how this was meant to describe the way the flight training was planned/carried out but my understanding of ‘ad hoc’ is that the term is used as a criticism, in the sense that something done as hoc is done hastily and can be ill thought out, but this might be my misunderstanding of its intended interpretation.
At best it might imply a very casual approach to flight training involving a student with circa 10 hours total time.

• What was the reasoning behind the decision to take the considerably high risk of conducting the early stages of flight training in a hostile environment i.e. at the end of a valley in a mountainous region, and not at the much safer environment of the airfield they had just departed from?

• Furthermore, why would an instructor elect to enter a mountainous region and transit to a training ground through a valley in a two (2) bladed helicopter, that is like any other two (2) bladed helicopter: susceptible to the possibility of low-G issues when encountering turbulence.

• And to do this with a low time student, open to inappropriate control inputs due to tension on the controls from natural elevated stress levels and lack of experience, at speeds of 100kts plus, where the aircraft will react more quickly to any inappropriate student control inputs.

• And with the knowledge that there is always the possibility of unexpected turbulence which, if encountered at the reported speeds, would possibly challenge an experienced pilot to not over control, let alone a 10 hour student?

• Apart from the high risk associated with the hostile mountainous training environment factor of the training flight, there seems to be a very casual approach to the flight training, highlighted by the fact that the training flight was ‘ad hoc’ with a 10 hour student.

• The instructor made a call to a person on the ground via his mobile phone! Even if this call was made via a hands free system, this is might be considered as an unwarranted distraction from the supervision of a low hours student flying at high airspeed in a hostile environment, with the ever present danger of unexpected turbulence.
To me this is an unforgivable drop in guard of instructor student supervision and a primary instructional duty to be alert to what the student is doing and guard the flight controls. Student pilots are unpredictable due in part to their elevated stress levels and things can happen very quickly, possibly beyond their ability to react…hence the need for an alert instructor.
There has always been the following amusing, but exceedingly valid anecdote, behind the student/flight instructor relationship:
“The student is intent on killing themselves and taking the instructor with them during the majority of their flight training.
The instructor is there to prevent it”.
The tragic accident that in part culminated in the safety issues associated with the R44 seems to me to be more a one of flight instruction issues and poor captaincy, rather than an inherent design defect with the aircraft.
It’s now approaching 4 years since the grounding of the R44.
What are NZ’s training industry and authority doing to address the recommendations listed in the said referenced accident report to enable the industry, that relies heavily on the R44 product for a living, to start flying the product again?
Mandating that the early stages of flight training be conducted at an airfield and it’s immediate local area and leave the hostile environment of the mountains to the advanced stages might be a start!
Nothing is ever going to be gained in the realms of flight safety and accident prevention if we allow political pressure, based upon ill informed and misguided information, put out there by the media to cynically sell news papers or the litigation circus, who are both in it for ulterior motives, to muddy the water.
What is required is a NZ Epiphany moment! In my opinion, NZ are in to the realms of ‘throwing the baby out with the bathwater’.
There has to be a realistic understanding that it is in the interest of the manufacturer to recognise a problem if it exists and rectify it. No manufacturer would blindly accept the negative impact of a fatal accident by blatantly refusing to confront it.
Robinson Helicopter Company (RHC) have always been exceedingly good at championing flight safety, accident prevention and pushing out flight safety information but if it is ignored then that is a pilot captaincy issue and not a product safety issue.
If the pilot purposely ignores and operates the aircraft outside the limitations set out in the Pilots Operating Handbook (POH), low-G demonstrations for example, which is also placarded in the cockpit in full view of the pilot, then this is not a product safety issue; its a pilot captaincy issue.
There are a number of very good flight safety tips published in the back of the (POH) that directly relate to the said issue:
Safety Notice SN-10 – FATAL ACCIDENTS CAUSED BY LOW RPM ROTOR STALL
Safety Notice SN-11 – LOW-G PUSHOVERS – EXTREMELY DANGEROUS
Safety Notice SN-24 – LOW RPM ROTOR STALL CAN BE FATAL
Safety Notice SN-32 – HIGH WINDS OR TURBULENCE
RHC have recently fitted an engine monitoring unit (EMU) as standard to their various types. There is also a current option for a cabin mounted camera.
This is a real step forward in the possibility of obtaining helpful information as to how the pilot lost control of the aircraft which, for obvious reasons, has not been available in the past. GB has clearly demonstrated that if you:

• Operate the aircraft within its limitations.

• Heed the advice given by the manufacturer on critical flight conditions.

• Conduct flight training in a well disciplined manner.

• Teach good pre flight planing.

• Propagate a good flight safety culture and relentlessly pursue it.

• And understand that most accidents could have been prevented prior to takeoff!

Then the Robinson Helicopter does not have an inherent design problem or a safety issue; it is as safe as the pilot at the controls, which can be said of any other aircraft type.
Going forward we need pilots to understand that when they are issued with their licence, this is just a licence to learn.
The pilot needs to adopt a real thirst for knowledge and understand that there is only one stupid question and that is the question you do not ask!
And…planning, planning, planning, as most accidents could have been prevented prior to takeoff!
So, thank you for 10 years without a Robinson fatal accident in GB and here’s to the next 10 years.        

Knowledge is flight safety helping to keep your RPM in the green.

R

This is ‘A Tea & Biscuit Production’ ® 

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

Welcome to our TEA & BISCUIT ARTICLES

MAIN ROTOR BLADE PERFORMANCE:

Time for a cup of tea and a nice biscuit!
The performance of your main rotor blade is several compromised if you allow dirt, bugs, pollen, grass cutting etc to build up on their leading edges.
On a typical R44 for example this type of contamination can steal as much as 5HP circa 7KIAS. Paint erosion on the main rotor blade leading edge can have the same effect if the paint edge is not feathered!!
Waxing the blades with a carnauba-type wax, also has a dramatic positive effect on the blades performance.
At a flying school in the UK, the school Chief Flying Instructor was discussing the seemingly low power problem with an R22 with me, asking for advice.
I went out to the said aircraft with him and inspected the main rotor blades, having seen the state of them the aircraft was hovered and the manifold pressure indication recorded.
We cleaned and waxed the blades and the aircraft was flown again.
The was a positive drop of indicated manifold pressure, circa 1.5in.
Simple and easy way to re establish the aircraft’s performance.
Of course, washing and waxing you blades also has a very positive effect on the damage caused by corrosion.
With the blade always rotating with positive pitch and particulates in the air, the paint on the lower surface of the blade will be eroded and very small pin prick type holes will be punched through the paint surface, leaving minute areas of aluminium skin exposed to the elements.
If left, corrosion will set in and cause serious damage.
If you keep your blades waxed, the wax will fill in the blemishes and prevent the corrosion!
In a salt water environment, the main and tail rotor blades should be washed after the last flight of the day, mild soapy water, if it is safe to put your hands in it, the it should be ok for the blades!!!
Never use anything other than hand power to feather the blade paint surfaces and always use a span wise hand movement, never cord wise!! Simple, yes.
Obvious, yes.
You would be amazed how many operators/owners I have encountered around the World, who have never been given this simple information!
I should also mention the fact that the main rotor skin to spar bond line should never be exposed. Always have the bond line painted, so that the paint is sacrificial and prevents damage to the blonding material. 

Knowledge is flight safety helping to keep your RPM in the green.

R

This is ‘A Tea & Biscuit Production’ ® 

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

Welcome to our TEA & BISCUIT ARTICLES

PROBLEMS WITH STARTING A HOT R44 RII ENGINE:

Time for that nice cup of tea and biscuit, whilst I give my personal opinion on the sometimes fickle R44 RII fuel injected engine start.
This post is in response to a request to do so and you will be pleased to see it is short!
There are going to be thousands of pilots out there who will have their own valid reasons to do it their way and if it works for you then ‘carry on’!
The first start is not usually a problem as it is just a case of finding the right amount of prime for your particular engine; therefore I am only covering subsequent hot engine starts.
Carbureted engines are often difficult to start when cold and easy to start when hot.
Fuel injected engines are often easy to start when cold but difficult to start when hot.
What we need for the hot engine is the ‘goldilocks zone’ – in this case favourable fuel temperature when the engine is hot to give us the correct fuel air mixture at the fuel nozzles that will start the engine.
I am taking the liberty of assuming there are no other underlying reasons for the engine not starting e.g. ignition problems.
The primary reason for the R44 RII electrical auxiliary fuel pump is to pressurise the fuel injector system for starting purposes.
Secondly, it gives redundancy in flight but as I will discuss below we could use it to help with hot engine starts.
There are two ways in which the auxiliary fuel pump receives electrical power with the battery switched on:
When the ignition key is selected to the prime position
When the clutch switch is placed in the engage position and there is engine oil pressure.
The current fuel injector system on the R44 RII is old technology; it’s mechanical not electronic.
The pilot is the primary sensing unit.
They have to judge the amount of time they prime the injector which will vary with the temperature of the engine and to an extent the ambient air temperature.
Altitude will play a part as the fuel injector idle fuel flow is set at the factory, so circa sea level.
If you are operating from a base at altitude, the idle mixture will have to be adjusted to compensate.
It’s pointless just sitting there turning the engine over on the starter motor in the vain hope it might start. Listen to what the engine is trying to tell you!
For example, if it is just turning over without firing then you most probably need more fuel; if it is spluttering and coughing then it’s probably too rich. In general for other prevailing conditions, I tend to under prime rather than potentially over prime as its easier to put a bit more in than take it out!
Note that after 3 consecutive attempted starts, rest the starter motor for 10 minutes.
So why does the fuel injected engine tend to give us starting problems when the engine is hot?
Here is my ‘two penny’s worth’:
The problem:
The fuel lines are located in hot areas, either in the engine compartment or on top of the engine crankcase.
When the engine is in a static condition (engine not running) these areas get hot from the residual engine heat and unfortunately the cowlings prevent the heat from dissipating.
In particular the fuel lines on top of the engine crankcase are in a very confined space (the fuel divider and fuel nozzle lines) inside the cooling baffles, which are also working against you by preventing heat dissipation.
The fuel injected engine is well known for its poor hot starting issues and idling characteristics.
This is due to the fuel getting very hot in the fuel lines and causing vapour locking.
Hot fuel has been a problem for a long time; it is not just an R44 RII issue.
RHC have managed to overcome the usual poor idle associated with an injected engine by circulating the relatively cool tank fuel through the lines and back to the aux tank.
This keeps the fuel lines cool and gives the R44 RII pilot a nice engine idle.
The fuel flow is almost twice what is needed for engine operation.
When the engine is running, the fuel Iines in the engine compartment are not a problem because the circulating fuel, plus the cooling air from your cooling fan, helps to keep the fuel cool in the lines and prevent the fuel from boiling and creating vapour locking.
However, a hot static engine will not have the benefits of fuel circulation or cooling air from the cooling fan, so it is the hot fuel in the fuel lines which can give the pilot a potential starting problem.
If you try starting the hot engine using the standard priming method, you are putting hot fuel from the fuel lines adjacent to the engine into the fuel divider and injector lines.
As I have already said, they are very hot due to their location on top of the crankcase and located inside the cooling baffles, which are preventing heat dissipation.
The sum of this situation is that there is no way of knowing if, or when, you have the correct amount of fuel at the nozzle due to the potential of vapour locking.
So how can we get over this problem?
Well, we can use one of the old tricks which is to get cool fuel into the divider and injector lines as soon as possible when we prime the injector system.
To do this we need to circulate the fuel using the auxiliary fuel pump with the mixture control in the off (fully lean) position.
This will remove the hot fuel in the fuel lines, giving us cool fuel right up to the inlet to the fuel injector, so that when you push the mixture control to fully rich and prime the fuel system you are doing so with cool fuel.
If possible when parked open engine compartment cowlings to allow for residual heat dissipation.
The R44 RII POH has now been amended to suggest this option in their 11 May 2020 POH revision.
They recommend running the auxiliary fuel pump for 30 seconds with the mixture control in the off position before attempting to start a hot engine, which is a bit longer than I used to do in my younger days.
With a bit of trial and error, the pilot should greatly reduce the problem of hot starts with the R44 RII engine using the above technique; it worked for me for years.
If you have found a way of dealing with difficult starts then please do share your methods as this is just my humble opinion.   

Knowledge is flight safety helping to keep your RPM in the green.

R

This is ‘A Tea & Biscuit Production’ ® 

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

Welcome to our TEA & BISCUIT ARTICLES

RR300 ENGINE FUEL SCHEDULING TO GROUND IDLE:

Time for that nice cup of tea and a biscuit or two!!!!!!! How about a quick run through the start sequence and fuel scheduling of your R66 RR300 engine!
The idea is to give the R66 pilot a rough insight into how your engine gets from a static position to ground idle rpm.
We need to look at a few components:
Firstly, the igniter switch.
This has two positions: ‘off’ and ‘enable’.
With the battery switched on and the key in the off position I can press the starter button and the starter motor will engage and accelerate N1 rpm.
It will continue to do so until I stop pressing the starter button.
Once I release the starter button, the starter motor will disengage and the N1 rpm will decay.
With the battery switched on and the key selected to enable,
I can press the starter button and release it, as this time the Generator Control Unit (GCU) will latch the starter motor into the starter mode until the N1 rpm reaches approximately 58% or the pilot places the key back into the off position.
It will also activate the igniter system for ignition purposes.
Therefore, the starting system is live in the conditions mentioned above; however, the starting system can be disabled by applying the rotor brake. There are two fuel control valve operating knobs: One below and adjacent to the pilot’s collective lever, which is the fuel shut off selector.
This switches the fuel off/on at a valve located at the cabin bulkhead, so before the engine.
The other is on the instrument pedestal, which is the fuel cutoff selector.
The fuel cut off switches the fuel off/on at the fuel control unit (FCU) on the right hand side of the engine and is used during the starting and stopping of the engine.
There are several system indication gauges that we must consider:
N1 compressor rpm, (gas producer turbine wheels 1 & 2) is from a signal taken from a speed sensor, located at the top of the engine gearbox, which is looking at the rotation of the compressor spur adaptor gear-shaft.
N2 rpm (power turbine wheels 3 & 4) is a signal taken from a second speed sensor on the lower left hand side of the engine gearbox, which is looking at the rotation of an N2 idler gear.
Measured Gas Temperature (MGT).
This temperature measurement is taken from a location in the turbine combustion gas path, at the exit of number 2 gas producer turbine wheel and the entry to no 3 power turbine wheel by a thermal couple harness.
Engine oil pressure indication.
The pressure indication is taken from a transducer on the right hand side of the engine, which changes a wet oil pressure to an electrical signal.
The engine oil pump is driven by the N1 gear train, hence, you should see some engine oil pressure as soon as the N1 rpm starts to increase and that is why you will notice that the oil pressure increases with N1 rpm increase, until the engine oil pressure relief operates at the set engine oil pressure.
The torque meter.
This is operated by the torque meter situated inside the engine gearbox.
Very simply, there is a torque meter piston, which is subjected to an axial thrust produced by helical gears within the N2 gear train.
In a non friction World, this axial thrust would be directly proportional to the power being demanded by the pilot.
Again, this is a wet oil pressure converted to an electrical signal by a transducer that is located under the engine oil pressure transducer.
The engine fuel scheduling components:
Engine driven fuel pump, driven by N1 gear train, receives gravity fed fuel pressure.
The FCU, is driven by N1 gear train and located as said above, on the right hand side of the engine.
It has has two controls attached to it, which are operated by the pilot:
Throttle Fuel cut off
The power turbine governor, which is situated on the left hand side of the engine and is driven by N2 gear train and is controlled by the pilot through the collective lever and an electrically operated beep actuator, whose operation is via a beep switch located at the end of the pilots collective lever.
The RR300 has a pneumatic fuel scheduling system, with the following pressures used:
Pc = pressure compressor, taken from the compressor scroll and delivered to the N2 governor and the N1 FCU via plumbing lines.
Pc is divided into Px bleed and Py bleed within the FCU
Px = Pressure acts on the Accelerator evacuated bellows.
Py = pressure acts on the governor evacuated bellows
Pa = pressure ambient Pr = pressure regulated air Pg = pressure governor reset (this pressure resets Py once the pilot opens the throttle to go from ground idle rpm to flight idle rpm).
From this point the power turbine governor will schedule the fuel based on N2 rpm. therefore, Pr & Pg really only come into play once the pilot has opened the throttle towards flight idle, so are not relevant during the start and acceleration to ground idle.
Subject to the pilot having completed the POH pre start check list, the pilot will continue to follow through with the start check list (the pilot is responsible for making sure that their reference material used is to the latest amendment, which if in doubt can be checked on the RHC website).
I am not going through the engine start procedure in this post, I am only trying to simply explain how the FCU schedules the fuel during the start sequence. When the pilot starts the engine the following happens:
With the throttle closed, fuel cut off in the cut off position and the igniter key in the enabled position the pilot will press the starter button and release.
At this point the starter generator will default to the starting mode and the GCU will latch the starter into the starting sequence until the N1 rpm has reached approximately 58% (at this N1 rpm the engine subject to ignition will become self sustained and the starter motor will disengage and revert to generator standby mode, the engine will continue to accelerate up to ground idle rpm).
The pilot is waiting for the N1 rpm to reach 15% (RHC have put a small white triangle mark on the N1 gauge face to assist the pilot in referencing the required rpm).
As the compressor rpm increases so does the pressure in the compressor increase, therefore the Pc pressure will increase.
This increase in pressure will be sensed in the following areas within the FCU:
The start derichment valve evacuated bellows.
A divider that will divide the Pc pressure into Px bleed and Py bleed pressures.
However, at this point Py pressure is vented to atmosphere through the start derichment valve Pa orifice.
Therefore, the only pressure increase is Px bleed, which acts upon the acceleration evacuated bellows.
At 15% N1 the pilot will move the fuel cutoff control knob fully in, thus allowing fuel to be introduced to the fuel nozzle.
At this point the igniter will cause ignition and the engine will ‘light off’.
The pilot now has to monitor MGT, oil pressure and acceleration time.
The combustion plus the starter motor will cause the engine to accelerate, increasing Pc pressure.
The increase in Pc pressure will at this point only be felt on the acceleration bellows via Px bleed pressure as the Py bleed pressure is still being vented to atmosphere through the start derichment valve Pa orifice.
The increased Px bleed pressure will cause the evacuated acceleration bellows to contract. The acceleration bellows are mechanically connected to the fuel metering valve, such that when it contracts it will move the fuel metering valve towards the open position, thus increasing the fuel delivered to the fuel nozzle and causing an acceleration of the engine.
As the engine accelerates, still with the aid of the starter motor, the Px bleed pressure also increases, (Px = Pc at this point) thus further contracting the acceleration bellows, causing the fuel metering valve to supply more fuel to the engine and the acceleration continues.
At approximately 30% N1 rpm, Pc pressure will be sufficient to close the start derichment valve, preventing Py bleed pressure from being vented to atmosphere.
Py bleed pressure now starts to increase, which is acting on the governor evacuated bellows, causing it to contract.
Just like the acceleration bellows, it is mechanically connected to the fuel metering valve and the contraction will cause the metering valve to move towards the open position increase fuel flow.
The engine is now accelerating due to Py, Px bleed pressure differential acting on the governor bellows. At approximately 47% N1 rpm a set of fly weights driven by the FCU via the N1 gear train will produce a centrifugal force sufficient to overcome a spring tension which holds a speed enrichment lever on to the Px restrictor orifice, when the lever moves away from the orifice this will allow Px bleed pressure to vent to atmosphere through the Pa orifice.
This causes a further change in the Py, Px differential pressures, Py now being greater (Py = Pc) is acting on the governor bellows causing the fuel metering valve to move further towards the open position. The engine continues accelerating (still with the aid of the starter motor up to approximately 58% N1, after which it will disengage and revert to generator stand by mode) therefore Py bleed pressure continues to increase, acting on the governor bellows causing the engine to continue to accelerate towards ground idle rpm.
At 65/67% N1 rpm the fly weight force is now sufficient too over come a spring tension holding the governor lever onto the Py restrictor orifice, thus allowing the Py pressure to vent to atmosphere via the Pa orifice.
The effect of this will be a slight reduction in Py bleed pressure, allowing the governor bellows to expand slightly and settle in a position that will meter the fuel for the given idle rpm required.
We are at idle rpm and you should understand that at this point the engine speed is governed by the FCU (N1 speed).
I hope that sort of makes sense!!!! I think that is enough as you will have run out of biscuits by now. The next tea and biscuit interlude in your busy lockdown schedule will cover fuel scheduling up to flight idle and in flight 

Knowledge is flight safety helping to keep your RPM in the green.

R

This is ‘A Tea & Biscuit Production’ ® 

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

Welcome to our TEA & BISCUIT ARTICLES

RR300 ENGINE FUEL SCHEDULING TO FLIGHT IDLE:

Time for a nice cup of tea and a biscuit for round two of the RR300 fuel scheduling saga!
Where were we?
Having got to ground idle, where the FCU driven by the N1 gear train scheduled the fuel up to this point, we now need to look at what happens when we open the throttle to take the RPM up to flat pitch flight idle.
In the previous post I mentioned the Power Turbine Governor (PTG), situated on the left hand side of the engine.
The PTG is driven by the N2 gear train and was not active in the fuel scheduling during the start up to ground idle.
I also mentioned two pressures, that again were not active during the start to ground idle, these were:
Pr = pressure regulated air
Pg = pressure governor reset
These pressures come across the engine in plumbing lines from the PTG and act on either side of a diaphragm within a PTG reset assembly attached to the FCU.
This diaphragm is connected to a shaft, called ‘the reset shaft’, which contacts the top of the Governor lever in the FCU.
If you remember, this governor lever sits on the Py pressure restrictor orifice and controls fuel scheduling via the governor bellows by allowing Py pressure to increase when the lever is seated on the Py restrictor orifice, or by moving off of the Py restrictor orifice to allow some Py pressure to vent to atmosphere via the Pa vent in the FCU.
This movement allows Py pressure changes acting on the governor bellows.
These changes in pressure acting on the governor evacuated bellows, mechanically move the fuel metering valve, thus adjusting fuel being delivered to the fuel nozzle.
Before we open the throttle, we need to know a few things that are inside the PTG (on the left hand side of the engine)
There are two restrictor orifices:
Pg pressure
Py pressure (this is engine overspeed protection)
A set of fly weights driven by the N2 gear train
A lever (PTG lever) that sits on the Pg restrictor orifice
An overspeed lever that sits on a Py pressure restrictor orifice
When the pilot opens the throttle from the ground idle position to the flat pitch flight idle position two things happen:
Firstly, the spring attached to the governor lever in the FCU is stretched, which increases the spring tension placing the governor lever back onto the Py restrictor orifice.
This will stop Py pressure venting to atmosphere through the Pa vent.
When this happens, an increase in Py pressure acting on the governor bellows causes the bellows to contract, moving the metering vale towards the open position, which will cause the engine to accelerate.
The second thing that happens is that the Pr, Pg re set valve in the governor reset assembly on the FCU closes, which now allows for the individual Pr, Pg pressures on either side of the reset diaphragm to take control of the fuel scheduling.
At this point the engine speed is now being controlled by the PTG, which is driven by the N2 gear train.
The engine is still accelerating as the lever is still being held onto the Py restrictor orifice by the increase in spring tension on the Governor lever, caused when we opened the throttle to flat pitch flight idle.
The engine will continue to accelerate until the N2 RPM is sufficient to cause the PTG governor flyweights to overcome the tension on a spring attached to the PTG lever.
When this happens the PTG lever moves off the Pg restrictor orifice, allowing some of the Pg pressure to vent to atmosphere through the Pa vent in the PTG. The reduction in Pg pressure allows the rest diaphragm to move the reset shaft such that it will push on the governor lever in the FCU sufficiently to overcome the governor lever spring tension and cause the governor lever to move off the Py restrictor orifice.
This will allow some Py pressure to be vented to atmosphere through the Pa vent in the FCU.
The reduction in Py pressure acting on the governor bellows, will allow the bellows to expand slightly, moving the fuel metering valve to reduce the fuel scheduling to that of 100% N2
The throttle is fully open and we are now at flat pitch flight idle and the fuel scheduling is being controlled by N2 RPM via the Pr, Pg pressure differential across the PTG reset diaphragm.
The next instalment of this ‘tea and biscuit story’ will be:
What happens when we go flying!! 

Knowledge is flight safety helping to keep your RPM in the green.

R

This is ‘A Tea & Biscuit Production’ ® 

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

Welcome to our TEA & BISCUIT ARTICLES

RR300 ENGINE FUEL SCHEDULING IN FLIGHT :

Ok, time for a nice cup of tea, a biscuit and a read of the final chapter of your RR300 engine fuel scheduling saga.
To recap:
The FCU on the right hand side of the engine, driven by the N1 gear train, scheduled the fuel in relation to N1 speed up to ground idle.
The PTG, on the left hand side of the engine, driven by the N2 gear train, takes over the fuel scheduling (now being scheduled in relation to N2 speed) from the point that the pilot opens the throttle to take the RPM up to flat pitch flight idle.
The PTG has a leaver which is connected to the collective lever via mechanical linkage.
This is connected to a governor beep actuator and then a cable to the lever on the PTG.
Moving the collective lever up and down will move the PTG lever; it’s correlated.
The N2 beep actuator in the system allows the pilot to make small adjustments to N2/Rotor RPM via a beep switch on the pilot’s collective lever.
So currently the engine is at 100% N2 and Rotor RPM, flat pitch.
INCREASING COLLECTIVE PITCH (LOAD):
When the pilot raises the collective lever, thus increasing the pitch on the main rotor blades, the engine fuel scheduling has to change (increase) in order for the engine to try and maintain a constant 100% N2/Rotor RPM.
So when there is a load applied to the engine (raising the collective lever) two things happen: Firstly, the load will momentarily cause the N2/Rotor RPM to decrease.
This will slightly reduce the N2 flyweight force that is holding the PTG lever off of the Pg restrictor orifice to move towards the orifice.
This will reduce the Pg pressure being vented to atmosphere through the Pa vent, therefore slightly increasing Pg pressure.
Secondly, a spring attached to the PTG lever is stretched via a cam attached to the PTG throttle shaft.
Please note – This is not the throttle on your collective lever in the cockpit!
This causes an increase in spring tension that will overcome the N2 flyweight force.
This allows a further movement of the PTG lever towards the Pg orifice, again further reducing the amount of Pg pressure being vented to atmosphere. This will also increase the Pg pressure.
The result of the increase in Pg pressure from both of these events will be felt at the fuel control reset shaft diaphragm, which will cause the diaphragm to relax the force being applied to the governor leaver in the FCU.
This will allow the governor lever to move towards the Py restrictor orifice, reducing the Py pressure being vented to atmosphere through the Pa vent. The result in the increase in Py pressure will cause the governor bellows to contract, moving the fuel metering valve towards the open position, scheduling an increase in fuel flow to increase N1 speed to compensate for the increase in the load demanded by the pilot when they raised the collective lever.
The N2/Rotor RPM remains at 100%.
REDUCING COLLECTIVE PITCH (LOAD):
Lowering the collective leaver will reduce the load on the engine, so again, two things happen:
Firstly, there will be a momentary increase in the N2/Rotor RPM.
The N2 flyweight response to this is to move the PTG governor lever away from the Pg restricter orifice allowing further Pg pressure to vent to atmosphere through the Pa vent.
Secondly, the PTG throttle lever will relax the stretch on the PTG lever spring, reducing the tension of the PTG lever.
This will allow the PTG to move further away from the Pg restricter orifice, further venting Pg pressure to atmosphere.
This reduction in Pg pressure will be felt on the fuel control reset shaft diaphragm, causing it to increase the pressure on the governor lever, moving the governor lever in the FCU away from the Py restricter orifice, allowing some Py pressure to vent to atmosphere through the Pa vent.
The result of this is a reduction in Py pressure being felt on the governor bellows which allows it to relax slightly, moving the fuel metering valve away from the open position.
This will re schedule the fuel metering and reduce the N1 speed to compensate for the reduction in load and therefore maintain 100% N2/Rotor RPM. There is one (1) more important assembly in the Pr and Pg pressure circuit, which is a double check valve and Pg pressure accumulator assembly.
This assembly is an externally mounted unit fitted within the Pg pressure line.
In a dynamic situation there are torsional oscillations induced by the the main rotor and drive train systems.
These torsional oscillations will be seen as fluctuating speed requirements and the PTG will try and reset the fuel scheduling to these perceived fluctuations in the power requirements.
This would give us fluctuating Pg pressure, which would cause the engine to be unstable, with oscillating N1, MGT and torque indications.
The job of the double check valve and Pg pressure accumulator is to dampen out these fluctuations in the Pg pressure system.
The result is that the engine does not respond to the torsional oscillations induced by the rotor and drive train.
Having had a rewarding flight, we land and need to bring the engine back down to ground idle RPM. When the pilot closes the throttle to ground idle position, two thing happen:
Firstly, the Pg reset valve opens, which removes the Pr/Pg pressures across the reset shaft diaphragm. This prevents the PTG from being involved in any further fuel scheduling.
Secondly, the spring tension on the governor lever is greatly reduced, allowing the governor lever to move away from the Py pressure restricter orifice, allowing a substantial venting of Py pressure to atmosphere.
This reduction in Py pressure allows the governor bellows to expand, moving the fuel metering valve towards the minimum flow stop, reducing the fuel flow to the fuel nozzle.
This will cause the N1 speed to reduce until the N1 flyweights move inwards sufficiently to allow the governor lever to move towards the Py restricter orifice, reducing the Py pressure being vented to atmosphere, thus allowing for a slight increase in Py pressure.
This will cause a slight contraction of the governor bellows, moving the fuel metering valve away from the minimum flow stop, to increase the fuel flow to establish N1 ground idle speed.
You are back to 65/67 N1 speed.
After a two (2) minutes cool down at ground idle N1 speed, you can shut down the engine.
The engine is stopped by the pilot moving the fuel cut off control to the cut off position (pulling the control out).
This will place the fuel control cut off valve onto its seat, shutting off the fuel to the fuel nozzle.
There is a check valve (P2) in the fuel line from the FCU to the fuel nozzle.
This check valve closes at approximately 20 PSI, which makes sure that all fuel flow to the fuel nozzle is stopped.
The engine will now coast down to a stop.
Altitude Compensation:
Any variation in the operating altitude or air density, will have a direct effect on the evacuated acceleration bellows located in the FCU (remember they were active during the starting of the engine and are subject to Px pressure).
Changes in the fuel flow required by changes in altitude or air density are automatically controlled by the acceleration bellows.
Compressor discharge Pc pressure is a reflection of N1 speed and air density.
Px and Py pressure are proportional to Pc pressure. Therefore, any changes to the air density will effect Px and Py pressures and will cause an expansion or contraction of the acceleration bellow, which in turn will cause a corresponding change to the position of the fuel metering valve and a corresponding change to the fuel scheduling to the fuel nozzle.
Engine overspeed:
The overspeed section within the PTG consists of an overspeed lever, spring and a Py pressure restrictor orifice, which can vent Py pressure directly to atmosphere through the Pa vent.
When the N2 speed is operating within its normal range, which is below 114%, the overspeed lever is seated on the Py pressure restrictor orifice preventing Py from venting to atmosphere.
If the N2 speed should exceed 114%, the flyweight force is sufficient to move the PTG lever to the extent that it will contact the overspeed lever forcing the lever off of the Py pressure restrictor orifice and allow Py pressure to vent to atmosphere through the Pa vent.
The effect of this will be a large reduction in Py pressure, causing the governor bellows to expand, moving the fuel metering valve to the minimum flow stop and reducing the fuel flow to the fuel nozzle, preventing the power turbine from over-speeding.
I think I have covered everything so you are free to go! 

Knowledge is flight safety helping to keep your RPM in the green.

R

This is ‘A Tea & Biscuit Production’ ® 

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

WELCOME TO THE ROTORY WING SHOW

POD CAST ON CARBURETTOR ICING IN THE ROBINSON R22 AND R44 ASTRO, RAVEN, RAVEN I

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

WELCOME TO THE ROTORY WING SHOW

POD CAST ON THE GOVERNOR SYSTEM IN THE ROBINSON R22 AND R44 TYPES

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

INADVERTANT IMC

Time for a quick tea & biscuits before I depart Kota Kinabalu to re join the UK helicopter fraternity.
I will be based at SHL for some three months, so if you want to pop in and have a cup of tea and a biscuit then please feel free to do so.
I am conducting courses so weekends would be best.
If there is anybody interested and I find time I will try and put on a ‘Tea & Biscuits’ safety day at SHL flying school facility. Weather being one of the big 3 helicopter pilot killers (the others are wire strike and Low RPM Rotor Stall) I thought I might quickly touch on it again.
Inadvertent IMC; an unplanned/fatal event! Over the years we have had:

The pilot waited for the fog to clear, decided it was ok and departed.
He immediately entered cloud and when trying to land, hit a tree he did not see!

The pilot continued the flight in IMC conditions…they died!

Departed from the pub at night in pouring rain and low cloud…they died!

Flew into a mountain at night in heavy rain and low cloud…one died!

Inadvertent?

Subject to the understanding that the pilots intention was not to go out there and kill themselves and their passengers, one has to assume that their decision to takeoff and continue with the flight made perfect sense to these pilots at the time.
So in my view we need to perhaps ask a few more “Whys”?!?
Was it the old over optimistic factor?
Was it the case that the pilot assumes that having a night rating and a little instrument familiarisation training is sufficient to fly at night in bad weather conditions?
Was it “I have done it before and I’m still here, so I know I can do it again”!
What makes a pilot who is not trying to kill themselves and their passenger/s decide it’s a good and valid decision to take off in known un flyable weather conditions?
Also, it’s one thing to risk your life but should the passengers, who put their lives in the hands of the pilot, not be given the opportunity to decide if they think the risk is worth taking?
As I have said many times before, it is the risk misperception and not high risk tolerance that usually leads to the pilot making a poor/fatal decision.
Having said that, the examples above would seem to indicate that the pilots knowingly decided to takeoff/continue to fly in the prevailing adverse weather conditions!
Perhaps the pilots assumed that their superior flying skills were such that the adverse weather was not going to be insurmountable, coupled with “after all, I managed last time”.
The problem with this sort of thinking is that the pilot is no longer around to learn from this false assumption.
All pilots should understand that It does not take long to sweep up your aircraft wreckage but the devastating emotional wreckage of the pilot’s family and friends will always remain.
So, how about if pilot’s who are willing to take the risk just stop and think for a moment about their family and friends? Just a final bit of advice.
When at the planning stage of your next flight, where weather is being considered, look for features that are likely to locally adversely effect visibility.
An example would be the local effect of wooded or forest areas.
The visibility might be acceptable over open ground but as you approach these areas the trees tend to drag low cloud down onto them.
This is partly due to the trees natural breathing cycle, water drawn up the through tree will evaporate from the leaves etc, causing a local drop in temperature and the corresponding condensation effect. Plan for these types of potential danger; degrading visual conditions sneak up on the pilot.
Plan to be startled!
Attempting to fly in bad weather is like England playing football in a major tournament.
You think you have a chance but you are pretty much guarantied to loose on the penalties!!

Knowledge is flight safety, helping to keep your RPM in the green.


R  

THIS IS A TEA & BISCUIT PRODUCTION®

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

PRE-FLIGHT CHECK

As the UK seems to be going full steam ahead towards a second lockdown, we can take this opportunity to partake of some much needed tea and biscuits!
So breakout the bone China again whilst I cover a quick subject that does not often get a mention. There are pilots out there that will remember that the pre-flight used to be called a pre-flight inspection, which was incorrect as the pilot is not usually qualified to inspect something!
Generally speaking, the definition of ‘inspection’ is the process of systematically examining, checking and testing aircraft structural members, components and systems, to detect actual and potentially unserviceable conditions.
So only a suitably qualified member of the maintenance organisation responsible for the aircraft maintenance can sign for ‘inspecting’.
A few years ago, the word ‘inspection’ was replaced with the word ‘check’.
So we now have a pre-flight check and the pilot will check that the item being checked is in the condition/position as stated, including any time limits or RPM percentages stated in the check list. Simple. It is either acceptable because it complies, or it fails because it does not!
If it fails the check, or the pilot is unsure, the pilot must revert to the appropriate person for advice. The pilot cannot make a decision as to the aircraft’s serviceability.
In other words the pre-flight check is simply a ‘go’ or ‘no go’ gauge.
I know that a lot of pilots are taught that the pre-flight check is only completed prior to the first flight of the day and subsequent checks are an abbreviated check.
Wrong!
Unless the manufacturer or the authority has published an abbreviated check, the pilot must complete the full published pre-flight check prior to every flight.
Make sure that any pre printed (non ManufactureManufacture) check card being used is as per the latest amendment, that it exactly follows the manufacture sequence and that there are no missing points.
The same of course applies for the pre-start, start and pre-take-off checks.
We have had numerous incidents/accidents due to wrong actions taken because the check card was out of date, or the sequence of the actions had been changed.
Again, if during the start or pre-take-off checks, a check results in an anomaly, it is simple!
It fails the check.
The pilot cannot and should not make a decision as to the aircrafts serviceability, other than shut it down and ask for advice from the relevant person. We have had too many incidents and accidents due to:
“Well, I thought it would be ok” or “Well, I thought I had cleared the problem” or “Well, I don’t understand it’s been like that for sometime and has never given me a problem before”…
So if you have a flickering clutch light, or the blades take longer than the time stipulated before they start to turn, or the mag drop is not as stated (and the pilot must see a drop), or the low rpm light comes on but there is no audible caution etc. etc.
Then it’s simple; the aircraft fails the check.
No if’s or but’s!
Shut down and seek appropriate advice and I do not care if you are in the middle of nowhere, late or in a hurry.
Do not be in a hurry to become a statistic!
Lastly, there are items that I have always thought should be added to the pre-flight, start, pre-takeoff and shut down checks but Frank has always said that if I had my way the checks would have to be on a toilet roll!!!!!
Having said that, I do think you should add the carb’ heat gauge condition check on the first pre-flight check of the day (Carb’ heat indicated temperature should read the same as the indicated outside temperature)
The pilot should check for a change in RPM when selecting full carb’ heat as this will give you a very positive indication of actual carb’ icing if you are in the conditions conducive to the event.
The pilot might want to conduct a magneto check prior to shut down.
This way you find any problem after a flight, rather than just as you want to go flying!
A caution on magneto checks, never conduct a dead cut check as this can cause serious damage to the magnetos.
I could go on but as Frank said ……………………!

Knowledge is flight safety, helping to keep your RPM in the green.

R  

THIS IS A TEA & BISCUIT PRODUCTION®

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

THE STARTLE EFFECT!

Time for yet another nice cup of tea which obviously gives you the opportunity to nibble a few biscuits.
I hope that you are all safely enjoying the freedom of flight after the long lockdowns. During the Helicopter Club of Great Britain webinar I briefly touched on the subject of the ‘startle effect’; the reaction being an instantaneous human ‘fight or flight’ response. In past posts and articles I have talked about the effects of stress on the pilot.
This has been mainly associated with an increase in pilot’s work load which can culminate into a ‘flight or fight’ response, resulting in the pilot becoming ‘overwhelmed by events’.
Although this effect can happen quickly it is not the same as the pilot being ’startled’ by an event. Let’s refresh your memory as to why the pilot can become ‘over whelmed by events’.
The pilot’s brain will react to stressful events such as an increase in workload and there will come a point when the stress levels are so high that the brain, and in particular the limbic system region, will perceive this as a threat and trigger the release of steroid hormones including adrenalin and the primary stress hormone cortisol which marshals systems throughout the body to deal with the threat thus increasing heart rate, blood pressure and blood flow etc.
Neurotransmitters are also released that will suppress (shut down) activity in areas at the front of the brain concerned with concentration, rational thought, short term memory and inhibition; thereby hindering the ability of the person to handle complex social or intellectual tasks and behaviours.
These mental events were critical in primitive times to allow the person to react quickly to the threat; ‘the fight or flight response’.
I do not care how good a pilot you think you are, when it comes down to it, the brain can be a great human leveller as we have no control over these mental events!
Sir Sterling Moss famously quoted; “Calling on my years of experience, I froze at the controls.”
So I think it is time to take a look at this other human factor that the pilot needs to be very aware of. In fact, in my very humble opinion, the helicopter training environment needs to be (if not already) aware of the ’startle effect’ as it should have some influence in the way the instruction relating to emergency procedures is conducted.
For more years than I care to remember, whilst conducting the European Robinson Pilots Flight Safety Course,
I have talked about ‘over reacting to benign indications in the cockpit’. One of the examples I give is the ‘startled’ reaction to the activation of the Low RPM caution system in flight.
I frequently ask the attending pilots the question: “How many times have you heard/seen the Low RRPM caution system activate during your training?”
The usual response is a few times during autorotation training but never during other phases of flight.
So my fear is that when the Low RRPM caution activates at some point in the future the pilot will be ’startled’ resulting in a rapid unraveling of events and culminating in an accident. So what is the ’startle effect’?
The ’startle effect’ has the following effects on the pilot’s physical and mental responses.
The physical effect (uncontrolled/automatic instant reflex) which means that the pilot can unwittingly induce large negative control inputs or even freeze on the controls as previously mentioned and quoted by Sir Sterling Moss!
I am sure that at some point in our lives we have all sat in the cinema and jumped out of our skin when we have been startled by an event on the screen, often resulting in our popcorn being thrown over the people sitting close by!
That is a physical uncontrolled/automatic instant reflex.
The mental effect disrupts cognitive processing which can negatively influence the pilot’s decision making and problem solving abilities.
It is very easy for the pilot to become over whelmed by the intense physiological responses.
These responses have the following effects: Increase in heart rate and blood pressure. Breathing increases in both rate and depth.
The liver releases addition sugar and the adrenal glands release adrenalin.
Muscles tense – (example: a caution I keep referring to when flying a Robinson product is that this will cause the pilot to unwittingly over ride the engine governor) so obtain plenty of manual throttle manipulation time to improve your manual throttle skill set. The pilot will sweat Brain activity is negatively effected as reactions will become more instinctive and less reasoned.
It has been found that the recovery from the mental aspect of the ’startle’ can take some 30 seconds after the event occurs and this will depend on the complexity of the task/s in hand.
So the pilot’s cognitive processing is disrupted thereby making problem solving and decision making very difficult, if not impossible.
The end result is that the pilot is just unable to react in a timely manner to the event and the accident happens or the pilot reacts in a negative way with the same outcome. The good news is that, despite the fact that the helicopter is a screaming, thrashing mass of assorted best worst compromises in loose formation, with some oil thrown in for good measure, they are becoming much more reliable, as are the systems within them.
The bad news is that this leads to pilot complacency.
In the old days when bacon was crispy and we had long hot summers, the helicopter was not so reliable, therefore the pilot had a high expectation of it all going horribly wrong.
The result was that when it did, it was expected, which reduced the possibility of the pilot being surprised or ’startled’.
Today, due to the increase in reliability, the pilot’s expectation of something going horribly wrong is low, which means that the level of surprise or ’startle’ is going to be much higher than in the ‘crispy bacon, long hot summer’ days.
I have always advocated the need to expose the pilot to actual warnings or cautions during training and subsequent continuation training.
If you can get the warning/caution light to come on in flight then do so.
Don’t just talk about it!
The low RRPM caution system is a prime example.
It is my view, there is quite a good possibility that the pilot is likely to have the Low RRPM caution activate at some point during their flying, more so if operating ‘hot, high and heavy’ or just high and heavy etc.
This is one caution system that the instructor/examiner can easily contrive to activate. The pilot should be exposed to this caution light during training and subsequent training, so that when the caution system activates when they are flying around enjoying the view, there is much less chance of them being ’startled’ and therefore increases the chances of a considered and timely reaction to the event, rather than brain freeze and death!
I remember the Low RRPM Caution system activating on the down wind leg on my first solo (non gov days); however, because I had been exposed to the caution system activating during the training, in my efforts to defy the helicopter’s incessant need to do something other than what I wanted it to do and the ridiculous thought that I might actually defy gravity,
I had actively used the correct recovery method many times, so the situation did not surprise me and the corrective action was taken without fuss.
The possibility had been planned for and I was prepared for it if the light came on.
It would seem from the answers that I get during the Flight Safety Courses, and the fact that governor off skills seem to be non existent in most cases, that my reaction on that first solo might not be the case today.
In my opinion this is where the training industry can take a very large step forward in the prevention of accidents.
The industry must not assume that if the student pilot can respond correctly to the initial emergency whilst the instructor is onboard, that they will be able to do so when they are flying around by themselves.
I say this for several reasons: Work load, stress levels, mental capacity etc, etc, will not be the same.
As mentioned above, there is in most cases a lack of throttle manipulation skills and a lack of Low RRPM skills etc.
During training, the student is very aware that they will get some sort of emergency during most flights pre and post first solo and so they have a heightened expectancy as the aircraft is being presented to the student by the instructor as unreliable.
There is another problem with the method in which emergencies are trained/conducted, however, some of this is outside the control of the training environment and the instructor/examiner.
Apart from a few systems, the instructor/examiner has to resort to verbally stating which system warning/caution emergency they wish the pilot to react too as they are unable to activate the warning/caution lights as a simulation.
So this, in my view, has an element of negative training as we are all aware that this is just not going to happen in the big bad world; the unhappy system is not going to inform the pilot of the problem.
What is going to happen is a warning/caution light is going to activate without telling the pilot which system it is in!
As the pilot has never actually been subjected to just a warning/caution light coming on in flight, there is going to be a very good chance what the result will most probably be…. they are going to be ’startled’
So what can we/the pilot do to try and reduce the ’startle effect’?
Actually, the ‘old hobby horses’ of mine that I have been harping on about for years pretty much cover what needs to be understood.
A better understanding of the aircraft systems: the way they interact with the pilot, the warning/caution lights associated with them and the position of those lights on the instrument panel/enunciator panel.
This will allow the pilot to react with knowledge and not guess work.
Obtain and maintain governor off skill set, which includes knowing how the engine throttle coloration to collective pitch works; both theoretical and practical.
The training industry is producing too many pilots who think that the aircraft is not flyable without the engine governor.
This is just not acceptable and needs to be corrected. Low RRPM recovery skill set. Know and fully understand the actions required for in flight emergency procedures. There was a very good question and interesting discussion going around on why the pilot should enter autorotation as the first action in the event of a fire inflight.
What this question raised in my mind was ‘detail’.
Are we assuming that when the pilot is reading the procedure that they are also understanding what is being said and why?
It is imperative that the instructor makes sure that the student pilot knows why and also that they fully understand each listed step and go beyond the text in the manual. They need to cover the full execution of the emergency on how the pilot is to fly the aircraft to a safe landing.
As an example, the fire inflight asks the pilot to initiate an autorotation but this does not require the same haste as entering autorotation as a response to an engine failure. The requirement for the fire inflight is to calmly initiate a descent rate, following through to an autorotation as this gives the quickest R of D in order to expedite putting the aircraft on the ground safely.
So now what is the pilot’s understanding of the landing?
Well, we spend a lot of time training the pilot to react to an engine failure which requires an entry into autorotation that will culminate in a landing without engine power available.
Whenever the pilot is asked to enter autorotation it is not going to be out of the bounds of possibility that they will assume that it will culminate in a landing without engine power available, however, this is not always the case.
In the case of the fire inflight then the pilot is asked to perform a normal landing if the engine is still running.
Caution!
Do not inadvertently blur the emergency procedures as they are stand alone and must be fully understood.
The pilot who recently asked the question about actions in the event of an engine fire inflight in a post to pilots out in the field, is a man after my own heart.
He stuck his head out above the parapet in full knowledge that there was a good chance of being shot at by those who seem to like to shoot people down.
It takes courage to put questions out there to your peers and I strongly advise any pilot who has a question to do the same.
Ask it on the understanding that the only stupid question is the one that you don’t ask! Enough of emergency procedures in this biscuit nibbling session as I have promised a post later in the year dedicated to why we check, or what is behind the reason for pre flight, pre start, pre takeoff, takeoff and hover checks, prior to departure.
Back to my ‘old hobby horses’ and how I think we can prevent the ’startle effect’.
Enjoy your flying as this is what it is all about BUT avoid being complacent and do expect the unexpected. Reliability aside then always adopt Murphy’s Law “Anything that can go wrong will go wrong”.
Fly defensively, adopt a good situation awareness skill set, monitor, mentally read the temperature, pressure and RPM indications, don’t just think ‘in the green’ and remember I have also warned you about the brain seeing what it expects to see!! Planning.
Anticipate what you will do in the event of the unexpected.
If the pilot has a clear mental picture of what actions to take in the event of possible problems occurring right up to the ‘rare event’, which is the one that most probably startles you, the pilot will be flying defensively.
It worked for me on my first solo.
If the pilot has planned for it then the information is stored in the brain and can be called upon if required during the current flight.
The next flight will require the same planning detail.
I do not care how many times you have completed the same flight as every flight is different and the pilot must understand this.
A small variable can make all the difference.
Read accident reports but when you do then remember that whatever the pilot did must have made sense to them at the time or that they were overwhelmed by the events, as you might be when you have your fatal accident.
Do not dismiss this because you think you are a better pilot. Make that safe landing decision early.
Do not wait for things to improve as they rarely do. Unraveling happens in one direction …further unraveling!
The pilot can only learn and adapt their inflight en route strategies if they are around for the next flight.
So before your next flight then ‘plan to be startled’
Even if we can downgrade ‘startled’ to ‘surprised’ we would be preventing the potential debilitating instant ‘fight or flight’ response, thereby giving the pilot more chance of successfully dealing with the event!
If I have missed out an ‘old hobby horse’ then do let me know.

Knowledge is flight safety, helping to keep your RPM in the green.

R  

THIS IS A TEA & BISCUIT PRODUCTION®

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

THE RETURN TO FLYING!

So I thought we should have a nice cup of tea and some biscuits whilst we ponder on a few thoughts before your first flight after having had such a long ‘downtime’.
Hopefully, all pilots will have some sort of routine that they follow after a timeout from flying; an example of this would be after you return from a holiday and then climb back into the cockpit.
I strongly recommend that the pilot should book a session with an instructor prior to their ‘first’ flight.
From a planning point of view, the pilot’s first port of call should be the POH or flight manual, which then needs to be checked against the manufactures latest revision.
A good and comprehensive read and digest (via brain and not stomach!) over a nice…yes, a nice cup of tea and biscuits!
This should include the safety tips at the back of the POH and any supplements that may affect the operational changes due to equipment fitted. Robinson in particular are very good at publishing information about previous causes of accidents; better to learn from them than learn by experience as you might not survive it!!! A good refresher on ‘critical flight conditions’ is a must.
Fully understand what they are, when, where and how to recognise the incipient stages of the relevant condition and how to safely recover from them.
Check the manufacturers website for published safety information as they often publish this in a letter or other type of document prior to its inclusion into the POH or flight manual.
The pilot should be very aware of any Airworthiness Directives that are pertinent to the type they fly and its equipment.
Of course, as the UK has now gained its independence, the UK. CAA has been busy publishing information on the new regulations and it is of paramount importance that the pilot is fully aware of anything that may affect them.
Ignorance is no excuse!
Check your aviation maps are up to date. Review the latest relevant accident reports issued by the AAIB and NTSB etc.
A good, long, preflight check will help with the transition from lockdown inactivity back into the aviation world.
Go and sit in the cockpit a few times in a static condition and quietly re familiarise yourself with pre start, start, pre takeoff and hover checks using the latest amended information.
Go through touch emergency procedures until you are happy with the actions, sequence of actions, and the correct response leading to a safe landing.
Revisit the different actions required to a caution or warning light.
A red warning light indicates a hazard that may require immediate corrective action by the pilot; revise the systems they are in and the manufactures required actions
An amber caution light indicates the possible need for future corrective action; revise the systems they are in and the manufactures required actions
The pilot has to understand that their stress levels will be elevated on the first few flights so going through procedures safely on the ground will stand the pilot in good stead in flight.
There will just not be the spare capacity to safely deal with a problem in flight if the pilot has to try and drag the information out of the dim and distant past.
Get some flying hours in before you think about taking passengers flying.
Passengers are a serious distraction which the pilot does not initially want due to their (the pilot’s) elevated stress levels and therefore reduced capacity.
Keep it simple.
There is always another day as long as the pilot is still around to see another day!
Those flying the Robinson product …please ensure that you are not ‘the’ pilot who destroys the UK’s brilliant ‘no product fatal accident’ run.
We only have a few months to go to 10 years.
If you get us to 10 years then I will organise a fly in at Sloane Helicopters facility at Sywell and will ‘stand’ the tea and biscuits!
Also as an extra incentive I may stop harping on.
Just a word of warning; do not try and cram this knowledge into a short period of time i.e. last minute.
Too much information is potentially as dangerous as too little because the brain is unable to retain it all as it’s a case of in one ear and out the other.
Do not get information overload; just take your time and keep checking your recall of previously covered areas.
The above are just a few pointers and are not supposed to be anything like the ‘definitive should do’ guide.
The pilot should be in no doubt that when things are going wrong they usually do so very quickly so there is just not sufficient time for the pilot to clear the cobwebs searching for the relevant response!
So clear any cobwebs on the ground prior to your flight.
Sloane Helicopter’s and Balearic Helicopter’s are now hosting my ‘Tea and Biscuits’ Zoom sessions which are very much informal question and answer chats.
If you are interested in joining in then please contact either Tinie of SHL (THofmeyr@sloanehelicopters.com) or Jonny of Balearic Helicopters (jonny@balearic-helicopters.com)
I wish you all a safe and enjoyable return to your passion whilst I go back to my lawnmower.

Knowledge is flight safety, helping to keep your RPM in the green.

R  

THIS IS A TEA & BISCUIT PRODUCTION®

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

THE OIL IN YOUR PISTON ENGINE

Time for a nice cup of tea and a biscuit
In this post I will only attempt oil v piston engine.
Turbine engines have a far more sophisticated oil system but that is not to say they do not have their own issues.
Putting oil into your helicopter’s engine is a routine task but there are some important aspects about oil that pilot’s need to know which can help to prevent some unscheduled expenses such as worn valve guides and glazed cylinders as examples.
Both are complex issues and have been continuous head scratching subjects since bacon was crispy and we had long hot summers!!!
The following is just trying to put across sufficient information that I think will be helpful without causing you to jump ship and dump the tea, which would not be the first time that ‘tea dumping’ had caused consternation!
Firstly, the owner, operator and maintenance staff should read, understand and follow the relevant manufacturer recommendations at all times.
We will attempt the subject of oil first:
There are fundamentally two classifications of oil used in aero engines:

* Straight mineral oil – no additive so the engine gets dirty and the oil stays clean! However, the oil will change colour over time as it oxidises.

* Ashless Dispersant (W) oil – it should be noted that this is not a detergent oil. The additive keeps particulates suspended in the oil separated so they do not form large masses within the engine that could block oil passages etc. So the oil gets dirty (turns black) and the engine stays clean. Straight mineral oil – example being Aero Shell 100 or 80 This oil is used during the engine/cylinder ‘break in’ period after overhaul or from new.

This period is usually for the first 50 hours from new or newly overhauled or when the oil consumption has stabilised.
During this time the piston rings are bedded into the cylinder wall.
This will be partly achieved by the breakdown of the oil film between the rings and cylinder wall, which will allow for slight metal to metal contact.
I know this might sound confusing as oil is normally there to prevent surface to surface contact but the use of the correct oil is one of the two (2) requirements that are critical for this purpose.
Firstly, new or newly overhauled cylinder internal wall surface and the face of the piston rings are not smooth.
In order to get a good gas seal the high points of the wall and ring surfaces have to be removed.
Straight mineral oil has a weak oil film strength, which can be ruptured to allow for this abrasion process to happen.
Therefore if the owner/operator uses the wrong engine oil during this break in period then the problem of ‘glazed cylinders’ becomes an expensive issue.
Using an ashless dispersant (W) engine oil during the break in period will prevent the very important abrasive contact action due to the oil’s higher oil film strength.
Also, the action of friction will lead to very high temperatures at the cylinder walls and will cause the additive in the ashless dispersant oil to cook in the groves of the honed cylinder surface and form a glazing.
Honing is the process where small scratches in a cross hatch, diamond configuration are put into the internal cylinder wall surface to hold oil for lubrication purposes during operation.
If glazing happens then the rings will be prevented from forming a good gas seal, resulting in low power and high oil consumption.
Glazed cylinders are NOT a warrantable claim!
The only course of action is to remove the offending cylinder/s and remove the glazing by re honing them….expensive!
The second critical requirement for correct ‘break in’ is the use of high engine power during the ‘break in’ period.
There is often a misunderstanding about how to treat a new or newly overhauled engine or cylinder.
The mistake is thinking that you should be gentle with the engine at the beginning and not pull too much power out of it for the first few hours.
This mistake can also be very expensive. In order for the piston rings to bed into the cylinder wall, the rings have to be forced out and onto the cylinder surface with sufficient force to break through the oil film.
The piston rings are designed such that combustion pressure will act on the rings and force them out onto the cylinder wall.
However, high combustion pressure is required to produce sufficient ring force to rupture the straight mineral oil film.
Therefore, the engine power used during the ‘break in’ period is also critical to bedding the piston rings in.
Herein lays a problem with new or newly overhauled engines fitted into helicopters.
The general rule to achieve a successful break in requires the engine to be operated at a minimum of 70 to 75% of rated power as soon as possible (remember we need sufficient combustion pressure to produce a force acting on the piston rings that will break through the oil film and give us the abrasive action required) for a period of time and then operated at a minimum of 65% of rated power for next 50 hours to break in the piston rings.
This high power is initially difficult to achieve with a helicopter as there are various systems that require dynamic balancing, which is mainly carried out on the ground at flat pitch requiring very little power output from the engine.
Whilst the engine is being operated at these low power settings, the combustion pressure produced in the cylinder is not sufficient to cause the piston ring to break through the oil film, thus there is a very good chance that cylinder glazing will start to occur.
To reduce the glazing possibility, the engine should be run in on a test bed IAW the full manufacturer requirements of a new or newly overhauled engine and this should include a period of time at maximum power, which starts the piston ring bedding in process.
So, when sending your engine away for overhaul make sure you request that a full post overhaul test schedule is completed to include the manufacturer requirements for the maximum power run for the full required duration.
One of the advantages of sending your engine to RHC for overhaul, is that they will do this as standard.
In the crispy bacon days we used to replace the engine oil and clean or replace the filter (depending on filter type) at the first 10 hours of operation, as the engine will produce metal particles during this time as normal initial wear occurs and it is important to remove these particles to prevent them from acting as a grinding medium and causing premature wear. The oil is then replaced and the filter cleaned or replaced after 25 hours from the first oil change.
Then every 25 or 50 hours depending on type of oil filter fitted or every 4 months, whichever comes first.
The owner/operator/maintenance organisation should follow the latest manufacturer requirements.
Ashless dispersant oil – example – being W100 or W80 (W means it has an additive).
This oil is normally used during the on going servicing.
As it’s a dispersant oil it will help prevent the buildup of combustion byproducts and carbon in various parts of the engine such as oil galleries.
This oil is used until there is a need to revert back to a straight oil; for example in the case of a cylinder replacement.
The W oil has a much higher film strength than straight mineral oil and therefore cannot be used during the recommended piston to cylinder wall bedding in period.
There might be exceptions to the above, which usually involve turbocharged engines, so manufacturer recommendations for oil usage must always be followed.
The 100 weight oil being more viscous than the 80 weight oil.
In the crispy bacon days we would use the W100 oil during the long hot summers and the W80 oil during the winter.
Of course now you have ‘semi synthetic’ or ‘multi grade’ oils, an example being W 15W-50, which is still a base mineral oil.
However, they both have a temperature upper limit, where, when reached, they will break down into carbon particles.
The obvious difference is that the semi synthetic oil has a better temperature range, mainly to do with it being more resistant to viscosity changes, so good for both winter and summer. There are a number of places in the Lycoming engine where this upper temperature limit is exceeded; hence if you look at a typical oil filter you will see carbon particles.
Carbon particles are abrasive.
Theoretically, the semi synthetic oil should produce less particulates than the full mineral oils, however, there seems to be no hard evidence to support this.
So, the use of oil tends to be based on aircraft usage and operator experience at given ambient conditions at their location.
So, what is the best oil? Well, from the cylinder valve wear issues it would seem to make no real difference. However, there are oils out there that have anti-corrosion and anti-scuff additives.
Examples being W100 plus, W80 plus and W 15W 50 etc.
These ‘plus’ oils have been produced for operators that fly infrequently, so corrosion becomes a problem due to inactivity and wear on initial start up due to oil loss between surfaces due to inactivity.
The worn cylinder seat, valve stem and guide are another issue and are complex but if you sift through the issues of:
Fuel chemistry – aeromatics, tetra-ethyl lead etc.
Fuel air mixture- more problems generally with carburetor engines – fixed fuel jet orifice. Byproducts of combustion.
Parallel valve cylinders v angled valve cylinders.
Operating temperatures, ambient and engine internal issues, understanding that some 50 to 75% of the heat generated in the engine is lost i.e. it does not get used to produce power. Therefore, this heat needs to be effectively transferred and dissipated. Etc, etc, etc….. they all have the potential to add to the cylinder valve problems.
So let’s go back to oil.
The oil has multi purposes and I am not going to insult your intelligence, so I will keep to my thoughts on what I consider to be some of the possible/probable causes of premature valve wear.
Carbon and the byproducts of combustion are abrasive and corrosive, therefore, the operator should try and keep these particulates to a minimum.
The use of a ‘plus’ oil as mentioned above could be considered as an option.
Over the years I have tried to get across to engineers, pilots and operators, that the oil change frequency should not necessarily be solely based on Lycoming recommendations of every 25/50 hours or 4 months (whichever comes first) but also on its colour!
One of the most important jobs the W oil (ashless dispersant) has to do is to absorb the engine’s combustion byproducts.
When the oil goes into the engine it’s a nice gold colour but will change its colour as it absorbs these products (remember, they are very abrasive and corrosive).
There is an exception to this which is when you are using a straight oil.
The straight oil causes the insides of the engine to become dirty, rather than the oil, so the oil remains reasonably clean.
If the W oil reaches a black colour, then there is a chance that it is no longer able to carry out this very important function.
It turning black means that it is becoming saturated with combustion byproducts (which it is designed to do) unless the owner/operator has an oil analysis carried out to check its still in good condition I advise that the oil should be changed.
As If left to continue in the engine, the unabsorbed particulates will cause damage to the internal moving parts, which include the cylinder valves and guides.
So, you change the engine oil based on its colour, unless you have the oil analysis carried out when the oil becomes black, rather than just at 25/50 hours or 4 months, which ever comes first.
However, do not exceed Lycoming’s recommended oil change requirements.
It’s the cheapest and most effective engine maintenance you can do.
Engine temperature.
Excessively high temperature at the cylinder valve face and seat is a problem.
There are things the pilot can do and things that maintenance engineers can do to help reduce the damage caused by the inherent high engine operating temperatures.
The pilot:
RHC have now advised on a timed cool down period prior to engine shutdown!
I banged my head on Frank’s office wall for years on this one, way back in the 1980’s, and have the bruises to prove it.
Two (2) minutes.
The same as you would in a Rolls Royce turbine engine for exactly the same reasons….to prevent thermal shock of the hot wetted parts in the engine, causing the oil to breakdown into carbon. In the piston engine, with the moving/sliding valves, the issue is twofold: Carbon build up (sticking exhaust valves)
Abrasive damage to the inlet valve guide/stem
So in short; a good cool down period prior to shutdown and keep an eye on the oil colour. The pilot sees the engine oil prior to every flight.
The engineer only sees it at 25/50 hour or 4 months.
I did understand Frank’s reasoning, which partly had to do with the R22 life at that time being based on engine running time, so you would encounter loss of engine life cooling down!!
One of the other considerations is that the oil in the rocker box area is free to enter the valve guides after engine shut down, as there is no oil seal.
So, if the cool down period is insufficient to reduce the temperature at the valve stem and face, this oil will break down into carbon deposits.
If the valve is open the oil can get onto the valve face and seat, resulting in carbon contamination, which can/will lead to uneven valve face and seat wear, which will also cause valve guide wear.
The engineer:
Tell the pilot to keep an eye on the engine oil colour and explain why.
The engineer working on the cylinder repair should understand that the valve seats and faces are the hottest parts of the engine and there has to be a good transfer of heat away from the valve seat to the valve face.
In the crispy bacon, long hot summer days, I for my sins used to overhaul Lycoming & Continental engines.
One operator had issues with his aerobatic aircraft engine valve seat and valves wearing prematurely.
My view was to increase the valve to seat contact area, thus increasing the ability of heat transfer from the valve face to the seat and away through the cylinder block to the cooling fins.
Lycoming give you a minimum and maximum contact area, I put the contact area close to the maximum.
It worked reasonably well!
The engineer should make sure the spark plugs are rotated every 100 hours to change their position in the cylinders, as one of the important effects of this is to keep the spark plugs from accumulating a lot of lead and carbon deposits in the lower plugs.
All new Lycoming cylinders have nitrided internal barrel surfaces.
This is a surface hardening process which provides very good wear properties but is susceptible to corrosion.
Never leave the engine for long periods of time without raising its temperature above the boiling point of water; so you have to fly it and not just do ground runs!
The use of a semi synthetic/multi grade oil with the anti corrosion/anti scuff additive should help with long periods of inactivity.
If you know the aircraft is not going to be operated for a long period of time, it is best to carry out the manufacturer recommended storage procedures.
Still awake? No! Ok…….the end!

Knowledge is Flight Safety, helping to keep your RPM in the green!

R  

THIS IS A TEA & BISCUIT PRODUCTION®

DEDICATED TO THE PREVENTION OF HELICOPTER ACCIDENTS

STARTING A HOT R44 RII ENGINE

Time for that nice cup of tea and biscuit, whilst I give my personal opinion on the sometimes fickle R44 RII fuel injected engine start.
This post is in response to a request to do so and you will be pleased to see it is short!
There are going to be thousands of pilots out there who will have their own valid reasons to do it their way and if it works for you then ‘carry on’! The first start is not usually a problem as it is just a case of finding the right amount of prime for your particular engine; therefore I am only covering subsequent hot engine starts. Carbureted engines are often difficult to start when cold and easy to start when hot.
Fuel injected engines are often easy to start when cold but difficult to start when hot.
What we need for the hot engine is the ‘goldilocks zone’ – in this case favourable fuel temperature when the engine is hot to give us the correct fuel air mixture at the fuel nozzles that will start the engine.
I am taking the liberty of assuming there are no other underlying reasons for the engine not starting e.g. ignition problems.
The primary reason for the R44 RII electrical auxiliary fuel pump is to pressurise the fuel injector system for starting purposes.
Secondly, it gives redundancy in flight but as I will discuss below we could use it to help with hot engine starts.
There are two ways in which the auxiliary fuel pump receives electrical power with the battery switched on: When the ignition key is selected to the prime position
When the clutch switch is placed in the engage position and there is engine oil pressure.
The current fuel injector system on the R44 RII is old technology; it’s mechanical not electronic.
The pilot is the primary sensing unit.
They have to judge the amount of time they prime the injector which will vary with the temperature of the engine and to an extent the ambient air temperature.
Altitude will play a part as the fuel injector idle fuel flow is set at the factory, so circa sea level.
If you are operating from a base at altitude, the idle mixture will have to be adjusted to compensate.
It’s pointless just sitting there turning the engine over on the starter motor in the vain hope it might start.
Listen to what the engine is trying to tell you! For example, if it is just turning over without firing then you most probably need more fuel; if it is spluttering and coughing then it’s probably too rich.
In general for other prevailing conditions, I tend to under prime rather than potentially over prime as its easier to put a bit more in than take it out!
Note that after 3 consecutive attempted starts, rest the starter motor for 10 minutes.
So why does the fuel injected engine tend to give us starting problems when the engine is hot?
Here is my ‘two penny’s worth’:
The problem:
The fuel lines are located in hot areas, either in the engine compartment or on top of the engine crankcase.
When the engine is in a static condition (engine not running) these areas get hot from the residual engine heat and unfortunately the cowlings prevent the heat from dissipating. In particular the fuel lines on top of the engine crankcase are in a very confined space (the fuel divider and fuel nozzle lines) inside the cooling baffles, which are also working against you by preventing heat dissipation.
The fuel injected engine is well known for its poor hot starting issues and idling characteristics.
This is due to the fuel getting very hot in the fuel lines and causing vapour locking.
Hot fuel has been a problem for a long time; it is not just an R44 RII issue. RHC have managed to overcome the usual poor idle associated with an injected engine by circulating the relatively cool tank fuel through the lines and back to the aux tank.
This keeps the fuel lines cool and gives the R44 RII pilot a nice engine idle. The fuel flow is almost twice what is needed for engine operation.
When the engine is running, the fuel Iines in the engine compartment are not a problem because the circulating fuel, plus the cooling air from your cooling fan, helps to keep the fuel cool in the lines and prevent the fuel from boiling and creating vapour locking.
However, a hot static engine will not have the benefits of fuel circulation or cooling air from the cooling fan, so it is the hot fuel in the fuel lines which can give the pilot a potential starting problem.
If you try starting the hot engine using the standard priming method, you are putting hot fuel from the fuel lines adjacent to the engine into the fuel divider and injector lines.
As I have already said, they are very hot due to their location on top of the crankcase and located inside the cooling baffles, which are preventing heat dissipation.
The sum of this situation is that there is no way of knowing if, or when, you have the correct amount of fuel at the nozzle due to the potential of vapour locking.
So how can we get over this problem?
Well, we can use one of the old tricks which is to get cool fuel into the divider and injector lines as soon as possible when we prime the injector system.
To do this we need to circulate the fuel using the auxiliary fuel pump with the mixture control in the off (fully lean) position.
This will remove the hot fuel in the fuel lines, giving us cool fuel right up to the inlet to the fuel injector, so that when you push the mixture control to fully rich and prime the fuel system you are doing so with cool fuel.
If possible when parked open engine compartment cowlings to allow for residual heat dissipation.
The R44 RII POH has now been amended to suggest this option in their 11 May 2020 POH revision.
They recommend running the auxiliary fuel pump for 30 seconds with the mixture control in the off position before attempting to start a hot engine, which is a bit longer than I used to do in my younger days.
With a bit of trial and error, the pilot should greatly reduce the problem of hot starts with the R44 RII engine using the above technique; it worked for me for years.
If you have found a way of dealing with difficult starts then please do share your methods as this is just my humble opinion.

Knowledge is Flight Safety, helping to keep your RPM in the green!

R  

THIS IS A TEA & BISCUIT PRODUCTION®