tail rotor failure at hover
Megan, that sounds REALLY scary and a mite unsurvivable outside the sim. Look at some videos of tail fails in a hover and see how fast those things spin - and very rapidly some nose down pitch comes in, or the aircraft rolls, and the aircraft is no longer level, it is rotating tail low/tail high/tail low and very disorientating. Tail then hits the ground. In the Huey in the 70s, we used to practice slamming the right pedal forward to demo how fast it could spin - the feeling of being thrown forward against the seat belt is strange and upsetting.
In the sim, it would be interesting to see the coupling that happens after a high-powered spinning climb to 1000' and then trying to poke the nose over. Splat follows soon after.
In the 76B sim at WPB, they just taught me to grab the throttles back and make some sort of controlled LEVEL crash.
In the sim, it would be interesting to see the coupling that happens after a high-powered spinning climb to 1000' and then trying to poke the nose over. Splat follows soon after.
In the 76B sim at WPB, they just taught me to grab the throttles back and make some sort of controlled LEVEL crash.
Megan, that sounds REALLY scary and a mite unsurvivable outside the sim. Look at some videos of tail fails in a hover and see how fast those things spin - and very rapidly some nose down pitch comes in, or the aircraft rolls, and the aircraft is no longer level, it is rotating tail low/tail high/tail low and very disorientating. Tail then hits the ground. In the Huey in the 70s, we used to practice slamming the right pedal forward to demo how fast it could spin - the feeling of being thrown forward against the seat belt is strange and upsetting.
In the sim, it would be interesting to see the coupling that happens after a high-powered spinning climb to 1000' and then trying to poke the nose over. Splat follows soon after.
In the 76B sim at WPB, they just taught me to grab the throttles back and make some sort of controlled LEVEL crash.
In the sim, it would be interesting to see the coupling that happens after a high-powered spinning climb to 1000' and then trying to poke the nose over. Splat follows soon after.
In the 76B sim at WPB, they just taught me to grab the throttles back and make some sort of controlled LEVEL crash.
Previously unpublished images the morning after the night before:
AC, was in the 76A at WPB back in the 80's. Can only assume it was something dreamt up by the instructor involved, as I said the sim would do it, but as I further said, placed absolutely no faith in the procedure. As John says,collective down, no time for procrastination.
I also used to fly in the FSI B212 sim in DFW, and was on the receiving end of all kinds of strange instructor-derived advice on handling TR failures - based on how the sim was replicating it. To illustrate how fictitious it was, in some extra time at the end of a session, where we were 'playing' on an aircraft carrier model at night, I asked for a TR drive failure soon after transitioning from the deck. I was able to catch it using sideslip, find an airspeed/power combination that allowed me to carry out a wide climbing circuit and then autorotated back down to the deck from around 1,000 ft. Lots of whooping from the back, and congratulations, but all I could think was "are you serious? Do you really think that's how the aircraft would behave in real life?"
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Throttles in the roof - during one sim session in a 76 level D we were taught, if single pilot (we always were), a tail drive failure in the hover could be handled, if power available, by climbing vertically to height (1,000 suggested), nosing over to gain airspeed, accept side slip, and fly to suitable, spot for auto. It worked in the sim, but in real life? Always had my doubts having seen a fully loaded Huey lose drive in the hover. First question is sim modelling accuracy. John Dixon might give his considered opinion.
Helicopter flying is not inherently dangerous, it's only as dangerous as you want to make it. Three decades with an offshore operator and they never had an accident, nor injured anyone.
Helicopter flying is not inherently dangerous, it's only as dangerous as you want to make it. Three decades with an offshore operator and they never had an accident, nor injured anyone.
However I got away from a control failure in another different type (355) after a teleflex failure at a similar point. The TR was providing some thrust, the spin was extremely uncomfortable, and used an aggressive nose over at somewhere near 500', I'm not sure, just took what I could see out of the window. The reason for doing it was I was into a crowded, congested area, with clear space in very short supply. The flight to safety was flown at a bank angle higher than I expected, but the run on landing was exactly as the trainers and manuals described.
Someone mentioned earlier the RFM point about controlling pitch and roll on the cyclic as you attempt to put the aircraft down after a drive failure, If the failure occurs in the cruise and you get into auto safely then from sim experience I can believe that, BUT, in the low level drive failure the spin was so violent there was no chance, the yaw/roll couple was bad and I believe that being chucked about in the cockpit I was into PIO due to the lateral G forces, but I'm not sure. Certainly it took a lot of T Cut before the aircraft was flyable again.
After those two experiences I've often considered the positioning of FCL's and engine control swithches, a pair of guarded kill switches on the P1 collective seem to be probably the best option, but in a drive failure in the S76 sim reaching up and cocking the FCL's certainly stops the spin, the aircraft then flopping onto the ground before your hand is back to the collective, the 332 and S61 did something similar, but those sims were early and there were a lot of differences between them and the aircraft.
SND
Last edited by Sir Niall Dementia; 1st Nov 2018 at 09:15. Reason: Sprlling and grammar
Throttles in the roof - during one sim session in a 76 level D we were taught, if single pilot (we always were), a tail drive failure in the hover could be handled, if power available, by climbing vertically to height (1,000 suggested), nosing over to gain airspeed, accept side slip, and fly to suitable, spot for auto..
Last edited by gulliBell; 1st Nov 2018 at 10:48.
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I'm intrigued at your rationale to justify such a teaching? There is no way that I'd have held the hover and gently lowered the collective following my loss of tail rotor in a high hover, at night, in my BK117. I'd have been in a world of hurt: instant dumping of the collective and a spread set of crosstubes gave a minimal rotation on the deck.
If I'd made contact with a higher rate of rotation then a roll over would have been almost guaranteed.
Apologies for the thread drift.
If I'd made contact with a higher rate of rotation then a roll over would have been almost guaranteed.
Apologies for the thread drift.
Where my interest lies, is I have not given much consideration to an abrupt loss of anti-torque during the later stages of a VTOL departure. I am keen to learn from others who may have some ideas on the most favourable technique. My feeling is that a rapid throttle chop and attempted AUTO from 120-200 feet and zero IAS may not be the obvious answer.
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"Throttles in hand helicopters". The theory of chopping the throttle and pulling the lever to cushion the landing is a really good idea...…..however, with the throttle frictions on and the necessary hand actions required, it adds an unnecessary degree of complexity to a simple procedure. Just don't dump the collective!
For bad TR events OGE like this accident, my ideas are somewhat limited as to the best action to take.
DB....I come from the Throttle Friction bfull on School.
I have no problem winding both of them off....and that is during normal times.....add some Adrenalin and it would get easier yet.
Having been in a Huey that had a tail rotor drive failure.....the rate of acceraltion of the spin is unbelievable.
by the third rotation the world outside becomes a blur.....and with the throttle chop the spin almost stopped by the time we touched the ground.
I have no problem winding both of them off....and that is during normal times.....add some Adrenalin and it would get easier yet.
Having been in a Huey that had a tail rotor drive failure.....the rate of acceraltion of the spin is unbelievable.
by the third rotation the world outside becomes a blur.....and with the throttle chop the spin almost stopped by the time we touched the ground.
Avoid imitations
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The problem with trying to maintain a level attitude in a rapidly rotating helicopter for more than a very brief period is (as SND wrote from personal experience) that cyclic inputs may not have the expected effect, even if the pilot was able to overcome the visual confusion caused by the rotation. Think about the trimmed position of the cyclic. The normal reference point for the fixed main rotor swashplate constantly changes once rotation begins. After 90 degrees of fuselage rotation, what was a pitch is now a roll, and vice versa. After 180 degrees of rotation, what was a pitch up is now a pitch down.
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The problem with trying to maintain a level attitude in a rapidly rotating helicopter for more than a very brief period is (as SND wrote from personal experience) that cyclic inputs may not have the expected effect, even if the pilot was able to overcome the visual confusion caused by the rotation. Think about the trimmed position of the cyclic. The normal reference point for the fixed main rotor swashplate constantly changes once rotation begins. After 90 degrees of fuselage rotation, what was a pitch is now a roll, and vice versa. After 180 degrees of rotation, what was a pitch up is now a pitch down.
In my experience of even the most reluctant learning students in the FSTD, plenty of practice and exposure will produce a favourable reaction from the pilot before the helicopter nose has passed through 90 degrees. And I mean not only during the recurrent training but on a repeat visit 6 months later with little prompting.
Whatever the outcome here, it provides another "hobby Horse" for me try ride in that the current EASA regulations allow us to spread the Emergency Procedures syllabus over a 3 year period. Many operators therefore, only schedule retrain and check TR malfunctions every 36 months. Clearly this sucks a bit. I would like to see regulations make a more discerning requirement to the effect that some emergency procedures should be practised and checked at every OPC. Lord knows we flog the sh*t out of the CAT A OEIs at every OPC, which lets be honest, are probably the easiest exercises we do.
Many TREs I know, despite the syllabus they are given, are doing this already and rightly so.
I've seen plenty of 212/412 pilots crank on the throttle friction so tight that you need a pipe wrench to undo them. I don't know why, it's just dumb. No hope of winding both throttles off with one hand if the TR drive fails whilst in hover. Certainly not if the guy in the left seat is the one driving. I'd get the throttles off in a 76 well before said 212/412 driver can wind theirs off.
Shy wrote: "The problem with trying to maintain a level attitude in a rapidly rotating helicopter for more than a very brief period is (as SND wrote from personal experience) that cyclic inputs may not have the expected effect, even if the pilot was able to overcome the visual confusion caused by the rotation. "
In my first hand experience of two tail rotor events; one was a fenestron "stall" incident on a Gazelle where we probably span in excess of 15 revolutions before I got the yaw stopped. The other was a slipping tail rotor drive belt on an Exec where the onset of yaw was quite gentle but the rate of yaw built up until the world was a blur.
Is was lucky on both occasion because the wind was calm and had no difficulty keeping either aircraft level. However, had there been much of a breeze, the outcomes of both events would almost certainly have been very different.
JJ
In my first hand experience of two tail rotor events; one was a fenestron "stall" incident on a Gazelle where we probably span in excess of 15 revolutions before I got the yaw stopped. The other was a slipping tail rotor drive belt on an Exec where the onset of yaw was quite gentle but the rate of yaw built up until the world was a blur.
Is was lucky on both occasion because the wind was calm and had no difficulty keeping either aircraft level. However, had there been much of a breeze, the outcomes of both events would almost certainly have been very different.
JJ
I've seen plenty of 212/412 pilots crank on the throttle friction so tight that you need a pipe wrench to undo them. I don't know why, it's just dumb. No hope of winding both throttles off with one hand if the TR drive fails whilst in hover. Certainly not if the guy in the left seat is the one driving. I'd get the throttles off in a 76 well before said 212/412 driver can wind theirs off.
Let's talk about what is really Dumb.
I've seen plenty of 212/412 pilots crank on the throttle friction so tight that you need a pipe wrench to undo them.
How many times did you have to pull the Tee Handles or use the fuel switches to shut down the aircraft with those Throttles held full open by the Pipe Wrench tight Throttles?
No hope of winding both throttles off with one hand if the TR drive fails whilst in hover.
How many hovering autorotations have you actually done without rolling both Throttles off simultaneously?
How do you execute a Hovering Autorotation in a Bell 212/412?
As to the S-76....explain how you can be quicker in moving the Engine Levers over your head and getting back to the Collective Lever than simply rolling the Collective Throttles on the 212/412 to the Ground Idle position with your hand on the Collective mounted throttles to begin with?
Right now....my opinion is you are talking Dumb...... I am willing to listen to your responses and change my mind.
Throttles in the roof - during one sim session in a 76 level D we were taught, if single pilot (we always were), a tail drive failure in the hover could be handled, if power available, by climbing vertically to height (1,000 suggested), nosing over to gain airspeed, accept side slip, and fly to suitable, spot for auto. It worked in the sim, but in real life? Always had my doubts having seen a fully loaded Huey lose drive in the hover. First question is sim modelling accuracy. John Dixon might give his considered opinion.
Helicopter flying is not inherently dangerous, it's only as dangerous as you want to make it. Three decades with an offshore operator and they never had an accident, nor injured anyone.
Helicopter flying is not inherently dangerous, it's only as dangerous as you want to make it. Three decades with an offshore operator and they never had an accident, nor injured anyone.
Next argument, Chopjock, your statements demonstrates that you have absolutely no idea of what you are talking about when it comes to CatA.
Height Velocity diagram is for basic certification requirements.
Throttles in the roof - during one sim session in a 76 level D we were taught, if single pilot (we always were), a tail drive failure in the hover could be handled, if power available, by climbing vertically to height (1,000 suggested), nosing over to gain airspeed, accept side slip, and fly to suitable, spot for auto
Folks....please do not try this at Home!
Care to tell us where you were taught that?
Had they ever tried to replicate that in an actual aircraft?
My experience in teaching at two different Sim Training facilities located at different manufacturers delivery locations would challenge both the technique being taught and the basis upon which it would even be discussed as the training is supposed to be based upon the RFM, the applicable Operators SOP's etc, and National Aviation Regulations (FAA, CAA, EASA, etc).
Show me anywhere that suggested technique fits under any of the above?
Avoid imitations
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DB,
I didn't mean to imply anything else - I don't think there is an absolute answer to this type of failure because of differences in aircraft design and how, when and where the failure occurs.
In the case of an IGE hover, in a helicopter where there is no immediate way of "rolling off" the "throttles", I think I'd lower the lever asap, as you say, and accept the yaw rate at touchdown. If I had a second crew member who could either retard the ECLs or switch the engines from flight to "Off" it would be a bonus, but he'd have to be very quick!
Edit: Just checked my S-76 RFM (more than a bit dusty now - I've not flown the type for well over ten years). The advice therein is to lower the collective then select both engine levers to OFF at about ten feet and use the collective to cushion the touchdown. You need two left arms to do that, or be lightning fast if you're at a ten foot hover!
Obviously, as an ex-sim instructor I totally agree with the rest of your post. Any sim training is of benefit but it was sadly neglected in the past by the UK military and elsewhere.
As I've posted on the forum before, I know of at least one RAF helicopter crew who said that without the sim training they had received, they probably wouldn't have survived 'their' tail rotor malfunction (albeit in this instance a loss of tail rotor control, rather than a total loss of drive). They ended up in the North Sea and the aircraft was recovered almost intact despite it not having floats fitted - although I'm led to understand that it suffered fire damage after recovery and never re-entered service!.
Shy, I am not suggesting there is anything like an absolute answer. However, I am convinced that exposure to TR Drive failures in the hover, in the FSTD, to overcome the initial "Startle Effect" will significantly improve the chances of success in the real helicopter. Of course all the hooded horsemen of the FSTD apocalypse rise up when we defeat the flight loop in the FSTD. Modelling is problematic as OEM data for these events are generally not available for obvious reasons. However, even if the FSTD modelling is dodgy, teaching a reaction to the event is still important.
In the case of an IGE hover, in a helicopter where there is no immediate way of "rolling off" the "throttles", I think I'd lower the lever asap, as you say, and accept the yaw rate at touchdown. If I had a second crew member who could either retard the ECLs or switch the engines from flight to "Off" it would be a bonus, but he'd have to be very quick!
Edit: Just checked my S-76 RFM (more than a bit dusty now - I've not flown the type for well over ten years). The advice therein is to lower the collective then select both engine levers to OFF at about ten feet and use the collective to cushion the touchdown. You need two left arms to do that, or be lightning fast if you're at a ten foot hover!
Obviously, as an ex-sim instructor I totally agree with the rest of your post. Any sim training is of benefit but it was sadly neglected in the past by the UK military and elsewhere.
As I've posted on the forum before, I know of at least one RAF helicopter crew who said that without the sim training they had received, they probably wouldn't have survived 'their' tail rotor malfunction (albeit in this instance a loss of tail rotor control, rather than a total loss of drive). They ended up in the North Sea and the aircraft was recovered almost intact despite it not having floats fitted - although I'm led to understand that it suffered fire damage after recovery and never re-entered service!.
Last edited by ShyTorque; 1st Nov 2018 at 16:32.
The beauty of teaching in the sim is that one meets all walks of life. [And the experiences they recall].
I have briefed (or should I say been briefed by) several crews over my years who have experienced TRF in the hover and/or in the cruise.
The hover left the 2 crews I dealt with - with a very easy dilemma: dump the lever and accept ones fate and trash the cab (which in their cases was that the crews survived) or pull for height - prolong the agony and die a violent death.
The cruise is more easily survivable because of the torque setting at which it happens - giving time to discuss matters.
ANY TRF at a high torque setting will lead to rotational disorientation either immediately or when the power is reduced. This causes complete loss of SA leading to loss of control of the aircraft invariably. Not to mention gravitational effects preventing the pilot [not handling] from reaching the throttles in one case!
I have briefed (or should I say been briefed by) several crews over my years who have experienced TRF in the hover and/or in the cruise.
The hover left the 2 crews I dealt with - with a very easy dilemma: dump the lever and accept ones fate and trash the cab (which in their cases was that the crews survived) or pull for height - prolong the agony and die a violent death.
The cruise is more easily survivable because of the torque setting at which it happens - giving time to discuss matters.
ANY TRF at a high torque setting will lead to rotational disorientation either immediately or when the power is reduced. This causes complete loss of SA leading to loss of control of the aircraft invariably. Not to mention gravitational effects preventing the pilot [not handling] from reaching the throttles in one case!