Gazelle accident Salisbury UK Jan 2012

[helihub]

Three people are thought to have been on board when the crash happened at the Churchfields Industrial Estate just after 9.30am.

Early reports are that all three people managed to get out of the wreckage, one was injured but no one was killed.

more details/photo here (http://www.salisburyjournal.co.uk/news/salisbury/salisburynews/9461923.Helicopter_crash_at_Churchfields/?ref=twtrec)

[206 jock]

"“I saw the whole thing out of my office window.

“The helicopter was hovering over by the trees and it seemed like the pilot was trying to find somewhere to land.

“He started to come down but the ground there is very uneven.

“It went out of control and crashed into the trees.

“Luckily the people managed to get out before it flipped over.

“It toppled over and the blades went into the ground. It was all mangled – there’s not much of it left."

A blue Gazelle, apparently. Not a great start to 2012.

[Lewycasino]

Photograph of Aircraft G-WDEV (http://www.caa.co.uk/applicationmodules/ginfo/ginfo_photo.aspx?regmark=G-WDEV&imgname=G-WDEV001&imgtype=jpg)

[61 Lafite]

Whoever recently bought it had a short tenure - ownership changed on 15th November 2011!

Lafite

[talkpedlar]

4th Gazelle airframe lost in barely 2 years IIRC.. and the previous 3 were all fatals..and w/x related. Maybe a training/licencing issue here.. it's not a
difficult helicopter to fly, after all. TP

[OvertHawk]

On the contrary - it can be a challenging and unforgiving aircraft in inexperience hands (in comparison to say an R44 or a jet-box).

There have been several instances of PPL's with comparatively few hours in total and very few hours on the Gaz coming a cropper - particularly with yaw / fenestron related issues.

Hope everyone recovers well.

OH

[toptobottom]

"He definitely had some sort of mechanical problem..." (http://www.bbc.co.uk/news/uk-england-wiltshire-16486011)

Glad they all got out ok. This could well be the last straw for the insurance companies which already hate the gazelle.

[rigidrotor]

I hope all are ok.

There are very few instances that require to land immediately in a gaz, so I am surprised where this attempt has taken place.

As for fenestron related issues, there are numerous statements of stalls etc non of which have any scientific basis, in depth trials by the manufacturer and EPTS could not reproduce "fenestron issues", gross mis-handling would be the likely cause in virtually all cases.

If the Gazelle was so difficult to fly it would not have been chosen as the military trainer and kept for so long

[ShyTorque]

As for fenestron related issues, there are numerous statements of stalls etc non of which have any scientific basis, in depth trials by the manufacturer and EPTS could not reproduce "fenestron issues", gross mis-handling would be the likely cause in virtually all cases.

I flew and instructed on the Gazelle at 2 FTS in the mid 80s and never heard of "Fenestron stall".

I went back to it some three years later for a CFS check ride and the term had by then been invented. First I heard about this was when I brought the tail round in a 12 kt wind to look out above and behind before departure and was instantly criticised for it; my examiner took control from me as it was apparently so dangerous :rolleyes:

Not sure how we survived that awful episode; I'd only done it thousands of times before, in far stronger winds with no issues, as had hundreds of other pilots.

[cpt]

Yes Shy Torque....I also have the feeling that a great fuss over nothing is made around tail rotor stall on shrouded tail rotor helicopters. Despite many thousands of hours logged on AS365 and few hundreds on Gazelle, this issue never had been a concern neither to myself nor with other pilots on this types of helicopters.

[md 600 driver]

Shy
Are you saying I shouldn't do clearing turns in a gazelle its too dangerous
Steve

[timex]

Their's nothing wrong with doing clearing turns in a Gazelle, you just have to use caution in strong winds.

[longbox]

Which is true of any helicopter regardless of the design or type

[Thomas coupling]

Be very careful what is said about Fenestron Stall, to newbie's.
There is a phenomenon where the "acceptance angle" at the shroud permits the tail rotor to accelerate significantly to such an extent that the aircraft will rotate well in excess of its operating limit. (The cab can rotate around its axis atleast once or even twice IN SECONDS before the uninitiated pilot knows what is happening).
As (quite rightly) mentioned, this is NOT a design flaw, or LTE. It is, how shall we say: "a shrouded tail rotor aerodynamic phenomenon" which ALL shrouded tail rotor pilots MUST be aware of.

The phenomenon is easily overcome by applying FULL and persistent opposite pedal until the spin stops...and it will.

The problem with the great unwashed is that IF they are not aware of this, then it will certainly take them by surprise and probably lead to them losing control of the a/c.

[212man]

tail rotor to accelerate significantly

For clarity - I assume you mean "the yaw rate to accelerate significantly"?

[Wizzard]

Be very careful what is said about Fenestron Stall, to newbie's.
There is a phenomenon where the "acceptance angle" at the shroud permits the tail rotor to accelerate significantly to such an extent that the aircraft will rotate well in excess of its operating limit. (The cab can rotate around its axis atleast once or even twice IN SECONDS before the uninitiated pilot knows what is happening).
As (quite rightly) mentioned, this is NOT a design flaw, or LTE. It is, how shall we say: "a shrouded tail rotor aerodynamic phenomenon" which ALL shrouded tail rotor pilots MUST be aware of.

Really? And what's happening to the main rotor RPM at this time?

[A.Agincourt]

So what is the maximum rate of yaw permitted and is there a directional restriction - that is left or right - or is any restriction applicable to both directions of yaw?

Best Wishes

[Thomas coupling]

212 and Wizzard: correct, my apologies :eek: I meant YAW RATE...phew. Thanks for that.

Agincourt, I forget the yaw rate limitations...is it 3 seconds for a full 360 normally?
Not sure what you are talking about re the rest?

[Savoia]

OvertHawk wrote: There have been several instances of PPL's with comparatively few hours in total and very few hours on the Gaz coming a cropper - particularly with yaw/fenestron related issues.
Yes, one recalls the event involving Jonathan Bunn (son of Douglas Bunn .. he of Hickstead Showground renown and former owner of G-AYTF and G-JUMP, both Bell 206's) in September 2001 flying G-BXZE.

An excerpt from the Accident Report (http://www.aaib.gov.uk/cms_resources.cfm?file=/dft_avsafety_pdf_500984.pdf) reads:


The helicopter was lifting off from the western side of the International Arena at the Hickstead Showground for a flight to Selsey. The pilot reported that the wind was calm and he lifted to ahover about 6 to 8 feet above the ground. He began a left pedal turn to position the helicopter fortransition over the open arena area to the east.

As the turn approached 180° from the initial heading,the pilot felt that he was unable to stop the helicopter turning left. The rate of turn began to increaserapidly.After some 10 to 12 rotations, the pilot elected to land the helicopter immediately while still turningrapidly to the left.

On touchdown, the right skid broke and damage was sustained during therotational deceleration. The helicopter came to rest upright and the pilot shut down the enginebefore vacating the helicopter through the door on the right side, which had come open during thelanding sequence.

The pilot reported that a witness on the ground had heard a 'bang' and a grinding sound when thehelicopter was commencing its spot turn to the left.

Subsequent engineering inspection by the maintenance organisation found that the tail rotortransmission was still connected. The fenestron fairing was buckled and there was evidence that thetail rotor blades had contacted the inside of the fairing while rotating at operating speeds, but thisprobably occurred during the ground contact. No tail rotor blade failures were noted. There werealso indications that a main rotor blade had made contact with the corner of the right side door. The engineer assessed that there was no mechanical failure noted that could have accounted for theaccident.

[A.Agincourt]

TC - Max Rate Of Yaw Permitted - is - what?

I am not sure meself but 15 degrees per second seems to ring a bell. Anyway whatever the limit is, if you do not exceed it and you operate within all other parameters, then FS is not an issue. There are loads of ex-floppy drivers out there with thousands of hours on the machine and very few 'known' instances of this potential effect.

Best Wishes

[helihub]

http://www.thisisbath.co.uk/images/localpeople/ugc-images/275774/Gallery/images/14389918/3463655.png

http://www.thisisbath.co.uk/images/localpeople/ugc-images/275774/Gallery/images/14389918/3463656.png

http://www.thisisbath.co.uk/images/localpeople/ugc-images/275774/Gallery/images/14389918/3463646.png

[ShyTorque]

Shy
Are you saying I shouldn't do clearing turns in a gazelle its too dangerous
Steve

MD 600,
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!

[talkpedlar]

.. 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

[AnFI]

Lack of Tail Rotor Education event....?

Generalising:
Current training does not teach the handling skills required to prepare pilots for this phenomenon - IMHO

[Thomas coupling]

Agincourt: I know, I have 3000hrs on type. I have worked with 3 guys who have had this, one of them did it on purpose!!!

[jellycopter]

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

[VeeAny]

BBC News interview with the pilot.

BBC News - Salisbury helicopter crash pair released from hospital (http://www.bbc.co.uk/news/uk-england-wiltshire-16511588)

[ShyTorque]

That explains the extreme coning angle, then.

Shame there wasn't a nice field underneath, though....

[TRC]

Shame there wasn't a nice field underneath, though....

Well, there almost was - a damn great sports field, which makes me wonder why he was at 60' over the trees and right next to a densely packed industrial estate.


...after the engine stopped delivering power at a height of about 60ft (18m).


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?

Just askin'.

[SilsoeSid]

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?

In the interview he said he was lifting out of a landing site!

[TRC]

In the interview he said he was lifting out of a landing site!

Oh - didn't play the video - sorry..

*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.

[SilsoeSid]

Chris Cannell, from Car and Commercial Services based at the estate, said: "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."
BBC News - Helicopter crashes at Salisbury industrial estate (http://www.bbc.co.uk/news/uk-england-wiltshire-16486011)

CAR & COMMERCIAL SERVICES
UNIT 2, STEPHENSON ROAD
SP2 7NP SALISBURY , WILTSHIRE

Google maps : 51.068822 , -1.811752


Hellava long "split second" :suspect:


"I picked the fluffiest looking tree".
Not convinced that was the only fluffy thing going on in that interview!
It's in the eyes ! (http://lifehacker.com/5847738/why-closing-your-eyes-and-disabling-other-senses-can-help-you-remember)

[SilsoeSid]

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."

[TRC]

"The human body, it's built to fight or flight"


Flight then fight in this case I think..