Chas Sheriff's 407 Mishap
Below the Glidepath - not correcting
Any work or disturbance of a flying control system should be followed by an independent or dual signature maintenance check, i.e an independent set of eyes to confirm the controls still operate in the correct sense and have been secured/locked as appropriately. This seems to have fallen down the cracks here, through omission or error.
Any work or disturbance of a flying control system should be followed by an independent or dual signature maintenance check, i.e an independent set of eyes to confirm the controls still operate in the correct sense and have been secured/locked as appropriately. This seems to have fallen down the cracks here, through omission or error.
Tail rotor failure and tail rotor control failure is known among the most difficult types of emergencies to be simulated accurately without a full motion rig. So, at least until it is known exactly what condition the tail rotor was in (full pitch, no pitch, negative pitch, anywhere in between, anywhere in between but moving, both blades the same or not....) I wouldn't be so quick to blame lack of training for anything. The difference between theory and practice is larger in practice than in theory.
The following users liked this post:
Yes....All professional training establishments......even the CFS is subject to that grain of wisdom theyt not?
Do RAF CFI's/QHI's teach whatever they fancy or are they expected to conform to approved standardized methods, procedures, and practices as a part of a formal curriculum and course of instruction?
Why would you think it odd for FSI or any other training system to use a similar method to formallze training standards and exercise a careful consideration when changing or altering those standards?
Aviation is an endeavor that involves change and progress as a constant......it takes time to effect useful and provident change.
Do RAF CFI's/QHI's teach whatever they fancy or are they expected to conform to approved standardized methods, procedures, and practices as a part of a formal curriculum and course of instruction?
Why would you think it odd for FSI or any other training system to use a similar method to formallze training standards and exercise a careful consideration when changing or altering those standards?
Aviation is an endeavor that involves change and progress as a constant......it takes time to effect useful and provident change.
The instructor's response to ACs demo speaks volumes about an organisation.
If he had said 'let me get the CFI so you can show him that' - that would be a progressive training organisation.
Are we not assuming the tail rotor was stuck in a fixed position?
With a loss of linkage, would it not be possible for the blades to travel and pitch to be variable?
If such a scenario is possible that could make it a bit more unpredictable and challenging to deal with.
With a loss of linkage, would it not be possible for the blades to travel and pitch to be variable?
If such a scenario is possible that could make it a bit more unpredictable and challenging to deal with.
The following users liked this post:
Two questions occur to me.
Isn't it a good idea to use the runway for a running landing if yaw is likely as skids skid better and trip less on tarmac than on grass? (Assuming he had enough control to hit a runway).
What level of training and licence does a US Police Lieutenant have? Is he likely to have had the levels of tail rotor failure training that have been described above?
Isn't it a good idea to use the runway for a running landing if yaw is likely as skids skid better and trip less on tarmac than on grass? (Assuming he had enough control to hit a runway).
What level of training and licence does a US Police Lieutenant have? Is he likely to have had the levels of tail rotor failure training that have been described above?
BR - yes a non-fixed TR pitch would make things considerably more difficult and the Leicester 169 crash showed what full travel to negative pitch can do - it looked very controllable on the first part of his approach - at least he is still around to give more details of what he had to deal with.
Mel2 - he may have had no access to a simulator for detailed TR malfunction training so I guess it would be limited to his Type Rating training and subsequent LPCs - plus whatever experience he had before on other types.
Mel2 - he may have had no access to a simulator for detailed TR malfunction training so I guess it would be limited to his Type Rating training and subsequent LPCs - plus whatever experience he had before on other types.
Originally Posted by [email protected]
BR it looked very controllable on the first part of his approach - at least he is still around to give more details of what he had to deal with.
Initially, it appeared there was enough control for a second attempt, or perhaps, just using the remaining runway to get it pointing in the right direction.
It skids quite nicely at a rakish angle, so the outcome is a little surprising.
If memory serves, Bell now has pretty decent sim facilities for the type, whether US services are put through that degree of training I would not know.
The question you raise is a good one that one hopes is addressed in the final report.
Join Date: Jul 2021
Location: Southern United States
Posts: 122
Likes: 0
Received 60 Likes
on
30 Posts
I confess I hadn’t watched the video till now, didn’t realize it was there🤣 As others noted he looked pretty good on approach, I wonder if the ground rush freaked him out, it’s almost like he was descending then was like “oh crap!” and ballooned up. It was like he was set up for a great run-on landing, like he had a good grasp of the process but not enough “reps” actually flying the profile?
When our guys go through their annual stands ride that’s unfortunately the only time they are able to do autorotations low level, terminating at a hover or rolling on (touchdown autos are not allowed) The ground rush is unnerving to me as a back seater for sure, tho most guys take the opportunity to do a few while the boss is in the other seat.
i wish we could do them as a crew more often but the regs say have to have stands pilot up front. And SOP says instrument rating required for the job but no instrument flying allowed. As others have already mentioned, risk aversion strikes organizations pretty often, right or wrong.
FltMech
When our guys go through their annual stands ride that’s unfortunately the only time they are able to do autorotations low level, terminating at a hover or rolling on (touchdown autos are not allowed) The ground rush is unnerving to me as a back seater for sure, tho most guys take the opportunity to do a few while the boss is in the other seat.
i wish we could do them as a crew more often but the regs say have to have stands pilot up front. And SOP says instrument rating required for the job but no instrument flying allowed. As others have already mentioned, risk aversion strikes organizations pretty often, right or wrong.
FltMech
60 Flt Mech - yes the ground rush is a problem - helicopter pilots are conditioned to reduce speed as they get close to the ground because they normally come to the hover. On a fast approach many pilots sub-consciously reduce speed to make the picture appear 'normal'.
Are we not assuming the tail rotor was stuck in a fixed position?
With a loss of linkage, would it not be possible for the blades to travel and pitch to be variable?
If such a scenario is possible that could make it a bit more unpredictable and challenging to deal with.
With a loss of linkage, would it not be possible for the blades to travel and pitch to be variable?
If such a scenario is possible that could make it a bit more unpredictable and challenging to deal with.
Pedal jams do not require committing to a bad approach or excessive urgency. Up to about 90deg off centre it’s possible to go around although at that angle you have to be aggressive. He looked perfect on approach just too high. Perhaps a second run lower would have gone better but who knows without been there.
Good tip is change speed or collective individually but never together. Small inputs too, unless aggressively accelerating with cyclic because you’ve got to slow
Based upon my experience developing and qualifying helicopter simulators with the FAA (from a test-pilot perspective) the flight model of a simulator is based upon actual flight test data. The data incorporates most phases of helicopter flight (hover, climb, descent, cruise and autorotation). Obviously, loss of tail rotor is not measured. Then engineers take the recorded flight data and turn it into a flight model. The flight model is the simulation. Test pilots then tweak it and confirm it to fit what they know as "real."
Since the dynamics of a loss of tail rotor can vary (immediate or slow onset, partial to total loss, component shedding, incidental damage, etc.), the resulting enactment you experience in a simulator is closer to fantasy rather than reality.
During development, the engineers apply the physics to the method selected for the loss of tail rotor scenario. Then the test pilots fly it and tweak it. Here's the important part to understand: the failure MUST be survivable otherwise there is no constructive point to the simulation; FSI doesn't exist to produce frustrated and hopeless pilots.
It has been my experience that most tail rotor failures when based upon just the engineering physics quickly lead to loss of control and catastrophic results. And the interplay of everything (environment, onset conditions, aerodynamics, dynamics and physics) makes it just a guess based upon some theory and a little experience. And we always needed to "calm" or "dampen" the theoretical guesses down to allow survival of the situation for most pilots.
Consider all of this the next time you step from the simulator slapping your back.
Since the dynamics of a loss of tail rotor can vary (immediate or slow onset, partial to total loss, component shedding, incidental damage, etc.), the resulting enactment you experience in a simulator is closer to fantasy rather than reality.
During development, the engineers apply the physics to the method selected for the loss of tail rotor scenario. Then the test pilots fly it and tweak it. Here's the important part to understand: the failure MUST be survivable otherwise there is no constructive point to the simulation; FSI doesn't exist to produce frustrated and hopeless pilots.
It has been my experience that most tail rotor failures when based upon just the engineering physics quickly lead to loss of control and catastrophic results. And the interplay of everything (environment, onset conditions, aerodynamics, dynamics and physics) makes it just a guess based upon some theory and a little experience. And we always needed to "calm" or "dampen" the theoretical guesses down to allow survival of the situation for most pilots.
Consider all of this the next time you step from the simulator slapping your back.
The following 4 users liked this post by JimEli:
It is obvious that trying to simulate a complete loss of a tail rotor would have limited value.
This accident has nothing to do with tail rotor loss, it was operational, from a drive perspective, control was impaired.
That is something that can be worked in a simulator, after all we can do that that in an actual aircraft to varying degrees, so I wouldn't write off time spent working on that scenario.
This accident has nothing to do with tail rotor loss, it was operational, from a drive perspective, control was impaired.
That is something that can be worked in a simulator, after all we can do that that in an actual aircraft to varying degrees, so I wouldn't write off time spent working on that scenario.
Agreed - TR drive/total failures are difficult to model but TR control failures (ie stuck pedals) are easier to model and also practice in the aircraft - as I mentioned earlier, doing stuck TR exercises in the aircraft to fast running landings on the AS365 proved the simulator teaching was valid.
Avoid imitations
Join Date: Nov 2000
Location: Wandering the FIR and cyberspace often at highly unsociable times
Posts: 14,576
Received 429 Likes
on
226 Posts
In the mid 1980s I was one of two RAF QHI pilots who were tasked by MOD to use a Puma simulator to come up with better guidance wrt tail rotor malfunctions. At that time there was very little in either the pilot manual or the flight reference cards of any use. Some of the “old school” RAF QHIs were of the blinkered opinion that if a tail rotor failure of any sort occurred (note the different wording to that I used) it could be resolved by shutting down both engines and autorotating. That’s all very well until a tail rotor control failure occurs where the TR is still producing thrust but that thrust isn’t controllable by the yaw pedals, especially one that sticks at positive pitch. In that instance, shutting down the engines might be the last thing a pilot ever did.
We came to realise that some control failures, ie those where the blade pitch runs away to either maximum positive, or maximum negative pitch, are likely to be non recoverable. The latter occurred in the Leicester football club disaster, where high main rotor torque was being used and TR blade pitch ran away to maximum negative, or close to it. There’s no getting away from that.
However, most modern helicopters have a safety device of some sort or other such that following a disconnect of the pilot controls the TR pitch is placed in a near neutral position. This should allow, in some cases, for the pilot to fly the aircraft for some sort of controlled landing; probably a running one.
Following our simulator work, we used to teach our RAF Puma students to try to achieve a configuration whereby the aircraft nose was held off to the side on the approach to a constant speed running landing and then to apply just sufficient (but very careful) collective pitch to bring the nose back into line for touchdown. This may result in running on at some speed. On the Puma the MR blades pass the nose from left to right so the nose had to be held off to the right. Raising the collective applies more MR torque and this brings the nose round to the left.
An aircraft with blades that rotate the opposite way, ie passing the nose from right to left, needs the nose held off to the left.
Without regular training on type this can be difficult to visualise in the air, especially once adrenaline kicks in. However, I used to tell my students that the safe side for the nose on the approach is the retreating blade side. This obviously works irrespective of aircraft type and hopefully pilots will remember that from the aircraft start up they just did! If that configuration can be achieved, there is a reasonable chance that a successful landing can be made.
If on the approach the nose swings from the “safe” side through the twelve o clock to the other side, it’s unsafe and things will get worse at touchdown so either more airspeed or less collective pitch is needed. Obviously, finding this out close to the ground is a very bd situation so if possible the pilot should carry out a dummy approach at some altitude before committing to a landing.
Fly safe out there!
We came to realise that some control failures, ie those where the blade pitch runs away to either maximum positive, or maximum negative pitch, are likely to be non recoverable. The latter occurred in the Leicester football club disaster, where high main rotor torque was being used and TR blade pitch ran away to maximum negative, or close to it. There’s no getting away from that.
However, most modern helicopters have a safety device of some sort or other such that following a disconnect of the pilot controls the TR pitch is placed in a near neutral position. This should allow, in some cases, for the pilot to fly the aircraft for some sort of controlled landing; probably a running one.
Following our simulator work, we used to teach our RAF Puma students to try to achieve a configuration whereby the aircraft nose was held off to the side on the approach to a constant speed running landing and then to apply just sufficient (but very careful) collective pitch to bring the nose back into line for touchdown. This may result in running on at some speed. On the Puma the MR blades pass the nose from left to right so the nose had to be held off to the right. Raising the collective applies more MR torque and this brings the nose round to the left.
An aircraft with blades that rotate the opposite way, ie passing the nose from right to left, needs the nose held off to the left.
Without regular training on type this can be difficult to visualise in the air, especially once adrenaline kicks in. However, I used to tell my students that the safe side for the nose on the approach is the retreating blade side. This obviously works irrespective of aircraft type and hopefully pilots will remember that from the aircraft start up they just did! If that configuration can be achieved, there is a reasonable chance that a successful landing can be made.
If on the approach the nose swings from the “safe” side through the twelve o clock to the other side, it’s unsafe and things will get worse at touchdown so either more airspeed or less collective pitch is needed. Obviously, finding this out close to the ground is a very bd situation so if possible the pilot should carry out a dummy approach at some altitude before committing to a landing.
Fly safe out there!
The following 2 users liked this post by ShyTorque:
Shy - that is exactly what we taught on the 365 and it worked.
We also taught how to assess your minimum approach speed by carrying out a level, very gentle decel (at a safe height so you could dive on speed if required) to identify when the nose started to break away.
Once the basic technique is understood then it can be finessed - but if you have never had any training you will be lucky to survive it.
Good to see the RAF being so proactive 40 years ago
We also taught how to assess your minimum approach speed by carrying out a level, very gentle decel (at a safe height so you could dive on speed if required) to identify when the nose started to break away.
Once the basic technique is understood then it can be finessed - but if you have never had any training you will be lucky to survive it.
Good to see the RAF being so proactive 40 years ago
The following users liked this post:
It is obvious that trying to simulate a complete loss of a tail rotor would have limited value.
This accident has nothing to do with tail rotor loss, it was operational, from a drive perspective, control was impaired.
That is something that can be worked in a simulator, after all we can do that that in an actual aircraft to varying degrees, so I wouldn't write off time spent working on that scenario.
This accident has nothing to do with tail rotor loss, it was operational, from a drive perspective, control was impaired.
That is something that can be worked in a simulator, after all we can do that that in an actual aircraft to varying degrees, so I wouldn't write off time spent working on that scenario.
All of this is exacerbated by something you may not be considering. The process of fine-tuning the flight model further distorts reality. Slightly tweaking one thing here, can have huge undesirable effects on something else. It could even result in unknown effects: things I lose sleep over.
For example, one aircraft I worked on didn't seem to have the yaw stability exhibited by the actual aircraft (or any aircraft for that matter). It would swap ends in cruise flight with insignificant amounts of pedal application. It was obvious some component(s) of the model were wrong. But how is the fix accomplished? Do you reduce the power of the tail rotor, fudge with the vertical fin contribution or fuselage influence, amplify the airspeed impact, or just increase the overall yaw stability factor? Et cetera. One avenue we toyed with resulted in a helicopter that no matter the amount of pedal applied it was incapable of turning in a hover. All of this contributes to the realism of the whole simulation.
Helicopter simulators might be closer to a unicorn than the real animal.
The following 3 users liked this post by JimEli: