Gazelle accident Salisbury UK Jan 2012
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Shy
Are you saying I shouldn't do clearing turns in a gazelle its too dangerous
Steve
Are you saying I shouldn't do clearing turns in a gazelle its too dangerous
Steve
No, certainly not saying that. But that particular CFS examiner advised me in future to carry out a 270 clearing turn (instead of my normal 90 degree one), to put the crosswind wind on the other side of the tail.
I accept that LTE /LFE (loss of tail/fenestron effectiveness) is a possible issue in some circumstances (can be a similar issue on many types). But I never experienced it personally in the Gazelle, despite doing some fairly extreme things with it as part of my job instructing on the type.
IIRC, the first time the RAF found an issue was when a basic student was flying a dual sloping ground training session, with a brisk crosswind. The Gazelle spun and then pitched nose down, giving them a few exciting seconds.
I haven't flown the type since the late 1980s, so if you fly a Gazelle and aren't aware of the "Fenestron Stall" phenomena I suggest you ask a current instructor what the current teaching is on the subject.
Edit: Just seen the photos above and note that at least one of the MRBs seems more or less intact. Now that's what I'd call a coning angle!
Last edited by ShyTorque; 11th Jan 2012 at 10:38.
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Interesting and constructive points..
.. I'm pleased I started the thread. For sure "when I were a lad" the recent revelations/guidance on yaw rates were not taught.. but there again, awareness of x/wind on TR/yaw was certainly drummed home... as it was on other types.
Have to say however that, when flown within limits, the 541 is not difficult to fly.. but like any 'copter will bite the uninitiated.
It is surely telling to compare accident statistics between civvy and mil Gazelle operators ... and then reflect on the benign operating conditions of civvy Gazelles..and the often challenging theatre of their mil bretheren.
Perhaps the CAA will review training/licencing rather than have a knee-jerk response; I surely hope so. Cheers, TP
Have to say however that, when flown within limits, the 541 is not difficult to fly.. but like any 'copter will bite the uninitiated.
It is surely telling to compare accident statistics between civvy and mil Gazelle operators ... and then reflect on the benign operating conditions of civvy Gazelles..and the often challenging theatre of their mil bretheren.
Perhaps the CAA will review training/licencing rather than have a knee-jerk response; I surely hope so. Cheers, TP
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Is this another LTEd... ?
Lack of Tail Rotor Education event....?
Generalising:
Current training does not teach the handling skills required to prepare pilots for this phenomenon - IMHO
Generalising:
Current training does not teach the handling skills required to prepare pilots for this phenomenon - IMHO
Fenestron Stall / Yaw divergence
Chaps
I've got about 800 hours on the Gazelle, about 650 of that in the RAF. I'd never experienced 'proper' LTE/FS/YD (whatever you want to call it) until a few years ago when conducting type rating training for a civilian pilot.
It was a warm, calm-wind day with a heavily laden 'stretch' Gazelle with non-optimised Fenestron. I asked the 'student' to conduct a Stuck Pedal approach, something we'd thoroughly briefed prior to the flight. We'd also briefed 'Fenestron Stall' in-depth the same morning.
During the latter stages of the approach, he let the speed decay too much and the nose yawed left beyond the '12 o'clock position putting the relative wind from the 1 o'clock position. I instructed him to go around. As he was doing so, I looked over my shoulder, to the a/c owner who was a pax in the back, and proclaimed 'This is Fenestron Stall territory!' to emphasise what had been covered in the earlier briefing. The stude should have done a cyclic only go-around but, he reverted to type, and pulled in some lever as he selected an accelerative attitude. As I looked forwards again, the world had already started to spin rapidly to the left.
In good CFS(H) fashion, I grabbed the sticks and stated 'I have control'. Never, in my whole instructional career have I ever been so wrong! I pushed in full right pedal (at least I thought I did) but the spin just accelerated. The world was a blur, I just faught to keep the horizon level. As there seemed to be no response from the right pedal, I tried reducing the pedal to see if it would help - it didn't. After several more seconds, I believe I said 'I think I've lost this one' or something like that to which the student shouted 'Get full right pedal in!' - at least he'd remembered the briefing! I duly complied and positively applied right boot (still conscious of not trying to over-torque - god knows why?) Immediately, but slowly, the yaw rate started to reduce and after what was probably another couple of full revolutions, the turn stopped and I settled back into a very wobbly, but very relieved hover.
My own take on Fenestron Stall / Yaw Divergence is that it DOES exist and that a degree of mishandling is probably required to induce it. I think the stronger the wind, the LESS likely it is to happen as it's probably a function of applied torque and the fenestron's attempt to counter it. If you've got wind, you've got translational lift and therefore less torque/anti-torque requirement.
I'm not saying that it's got anything whatsoever to do with the recent crash in Salisbury however.
JJ
I've got about 800 hours on the Gazelle, about 650 of that in the RAF. I'd never experienced 'proper' LTE/FS/YD (whatever you want to call it) until a few years ago when conducting type rating training for a civilian pilot.
It was a warm, calm-wind day with a heavily laden 'stretch' Gazelle with non-optimised Fenestron. I asked the 'student' to conduct a Stuck Pedal approach, something we'd thoroughly briefed prior to the flight. We'd also briefed 'Fenestron Stall' in-depth the same morning.
During the latter stages of the approach, he let the speed decay too much and the nose yawed left beyond the '12 o'clock position putting the relative wind from the 1 o'clock position. I instructed him to go around. As he was doing so, I looked over my shoulder, to the a/c owner who was a pax in the back, and proclaimed 'This is Fenestron Stall territory!' to emphasise what had been covered in the earlier briefing. The stude should have done a cyclic only go-around but, he reverted to type, and pulled in some lever as he selected an accelerative attitude. As I looked forwards again, the world had already started to spin rapidly to the left.
In good CFS(H) fashion, I grabbed the sticks and stated 'I have control'. Never, in my whole instructional career have I ever been so wrong! I pushed in full right pedal (at least I thought I did) but the spin just accelerated. The world was a blur, I just faught to keep the horizon level. As there seemed to be no response from the right pedal, I tried reducing the pedal to see if it would help - it didn't. After several more seconds, I believe I said 'I think I've lost this one' or something like that to which the student shouted 'Get full right pedal in!' - at least he'd remembered the briefing! I duly complied and positively applied right boot (still conscious of not trying to over-torque - god knows why?) Immediately, but slowly, the yaw rate started to reduce and after what was probably another couple of full revolutions, the turn stopped and I settled back into a very wobbly, but very relieved hover.
My own take on Fenestron Stall / Yaw Divergence is that it DOES exist and that a degree of mishandling is probably required to induce it. I think the stronger the wind, the LESS likely it is to happen as it's probably a function of applied torque and the fenestron's attempt to counter it. If you've got wind, you've got translational lift and therefore less torque/anti-torque requirement.
I'm not saying that it's got anything whatsoever to do with the recent crash in Salisbury however.
JJ
BBC News interview with the pilot.
BBC News - Salisbury helicopter crash pair released from hospital
BBC News - Salisbury helicopter crash pair released from hospital
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That explains the extreme coning angle, then.
Shame there wasn't a nice field underneath, though....
Shame there wasn't a nice field underneath, though....
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Shame there wasn't a nice field underneath, though....
...after the engine stopped delivering power at a height of about 60ft (18m).
Just askin'.
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If he was on approach to land in the open area - why else would he have been at at 60' before the engine quit and not able to make it to open ground?
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In the interview he said he was lifting out of a landing site!
*Thinks* MUST pay more attention.
But - IF, and I say if the take-off site was in the sports fields, why was he only at 60' when the wheels fell off? heading for a treeline and an industrial estate, with a very big flat un-cluttered area to play with.
Last edited by TRC; 11th Jan 2012 at 21:14.
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Chris Cannell, from Car and Commercial Services based at the estate, said:
BBC News - Helicopter crashes at Salisbury industrial estate
CAR & COMMERCIAL SERVICES
UNIT 2, STEPHENSON ROAD
SP2 7NP SALISBURY , WILTSHIRE
Google maps : 51.068822 , -1.811752
Hellava long "split second"
"I picked the fluffiest looking tree".
Not convinced that was the only fluffy thing going on in that interview!
It's in the eyes !
"Originally we heard a chopper flying over very low over the top of the workshop and went out to have a look.
"We initially thought it was the police helicopter landing at the field at the back.
"He definitely had some sort of mechanical problem - obviously couldn't land in the fields behind because of the water, and has made his way back across the council yard to try and get, I would think, to the football pitches at the back.
"He's done a 180 degree turn and then all of a sudden the chopper has nose-dived and caught the trees.
"He manages to pull the nose back up, which I was quite surprised about, and then it just disappeared behind the trees and the thud."
"We initially thought it was the police helicopter landing at the field at the back.
"He definitely had some sort of mechanical problem - obviously couldn't land in the fields behind because of the water, and has made his way back across the council yard to try and get, I would think, to the football pitches at the back.
"He's done a 180 degree turn and then all of a sudden the chopper has nose-dived and caught the trees.
"He manages to pull the nose back up, which I was quite surprised about, and then it just disappeared behind the trees and the thud."
CAR & COMMERCIAL SERVICES
UNIT 2, STEPHENSON ROAD
SP2 7NP SALISBURY , WILTSHIRE
Google maps : 51.068822 , -1.811752
Hellava long "split second"
"I picked the fluffiest looking tree".
Not convinced that was the only fluffy thing going on in that interview!
It's in the eyes !
Purveyor of Egg Liqueur to Lucifer
Someone else can comment on the statement;
"The human body, it's built to fight or flight, The adrenaline kicks and you just do your best. It's 10% percent skill and 90% good fortune."
