Sheffield Today 04/02/07 1500hrs

[contrail]

Was at Sheffield today, preflighting aircraft for return sector when heard loud bang.
Looked up & saw Schweizer 269 G-TAMA about 100feet away, on the apron, rocking violently from side to side with high RPM on rotors. Believe it was shortly to have gotten airborne. It came very close to toppling on its side. As Rotors slowed down, it became apparant all the blades were no longer evenly spaced and some major mechanical defect had occurred at rotor hub (guess thats what you call it....... i'm a fixed wing chap).
The fire services were in rapid attendance.
Anyone know anymore specifics?

[nigelh]

pound to a penny it was ground resonance . If you dont either cut the throttle as soon as it starts or take off ( this can end up in disaster as i know to my cost !!! A few weeks in hospital and a blade thru the cockpit ). This is usually caused by the oleo,s ( suspension on skids ) being low or uneven.

[Whirlygig]

A bit like this? (http://uk.youtube.com/watch?v=-LFLV47VAbI)

Cheers

Whirls

[nigelh]

yes a bit !! but in the 300 it can fully develop and rip itself to bits an awful lot quicker than that :eek:

[Whirlygig]

Yeah but G-TAMA is a 269D i.e. a 330 but point taken!!

Cheers

Whirls

[md 600 driver]

nigel

was it you that did it at sherburn years years ago whern the aircraft disintgrated

steve

[A.Agincourt]

Think you might find that the S333 suffered a MR head component failure and that any visible sign of GR was simply a secondary effect to that. The fire crew reported a loud bang heard above the engine during the run down period. That would seem to suggest something other than an undercarriage issue. However, rather than speculate, why not ring them and ask?

Best Wishes

[Helinut]

Good job it happened on the ground then :eek:

[A.Agincourt]

Ohhhhhh Yes indeed.

Best Wishes

[nigelh]

If it was a failure in the head then i would imagine the whole fleet would be grounded by now :eek: Ground Resonance is more likely the cause of the failure but if anything else you certainly wont be getting me into one of them !!
No , mine was a number of years ago amongst jumbos etc at Houston Intercontinental Airport . I was a passenger , my friend took off and then the blades started coming through the cockpit and we nosed straight in and it exploded . Got the photos but nothing left other than blades.... interesting part was the first fire tender was empty :ugh: and i was on fire :eek:

[A.Agincourt]

nigelh: If it was a failure in the head then i would imagine the whole fleet would be grounded by now. Ground Resonance is more likely the cause of the failure From what I have learned, the aircraft was in the 2 minute run down period following a ground run. If GR was the main issue then it would have occurred at an earlier point in time and not many minutes later sat at ground idle. Ground resonance doles not produce a loud 'bang'. Failure as a consequence of GR might do so but in this case it seems that the bang preceded anything else.

my friend took off and then the blades started coming through the cockpit and we nosed straight in and it exploded . Got the photos but nothing left other than blades.So in this event, you were in fact airborne? Then it could not have been GR eh? Or are you saying GR occurred on the ground and the pilot pulled away to get out of it and then there was a failure?:confused:

Best Wishes

[nigelh]

in my case the lift off was too late and the failure occured as we lifted i would guess. I still do not believe that a head will just fail on ground run without it being from ground resonance . The bang will have been the failure itself. As i said bfore it can all happen very quickly. That is why you should ALWAYS wear your seat belt doing ground runs as you can get thrown through thwe windshield into the blades ....which will ruin your day :{

[Chopper Doc Junior]

Ground resonance can also be caused by damper failure and have nothing to do with the condition of the oleos.

[Whirlybird]

Isn't G-TAMA a Schweizer 333?

[A.Agincourt]

Whirlybird: Isn't G-TAMA a Schweizer 333?

Yes it certainly is. According to SACUSA anyway.

http://www.sacusa.com/helicopters/333.asp


Best Wishes

[Efirmovich]

We are at it again ! It's amazing how some Ppruners can remotely diagnose the cause of crashes, what happened, why aircraft fail etc,etc with virtually NO facts,,,,,, !!! :ugh:

May be the transmissoin siezed and all the blades broke off !!

The sound on my Sony telly keeps going off ??? any thoughts,, full fuel, frictions off, Hyd on and the wx is cavok :ok:

E.

[nigelh]

Efirmovich You are on the wrong site ....this site is for people to speculate on and even sometimes have a bit of fun . May i redirect you to the other site www.gogne.co.uk ( grumpy old git network ):D
As for your sony i can only imagine it is worn out from over use , maybe you should get out more :ok:
I still think head failure is unlikely . Does it have lead lag hinges like the 500 as i have heard of those breaking in flight. The blades will stay in line due to centrifugal forces but will move when rrpm drops . ( i think )

[212man]

I still do not believe that a head will just fail on ground run without it being from ground resonance

So what causes head failures in the air then?

[nigelh]

212 i am not aware of any head failures in the air ....can you enlighten us ?
The only reason i go for G R is that it is the only thing that i know of that could effect any of these type of aircraft and will almost always result in head damage at least. One does ( if you are actually flying helis on a daily basis !!!) actually hope that structures like heads do not just fail for no reason:eek:

[soggyboxers]

nigelh,

There have been many examples of main rotor head component failures in flight. One very good friend was killed in the first S76 which suffered spindle failure and I knew the pilot of the S61 which suffered th same fate. Then there was the S76 in the Southern North Sea in which all died when a blade failed a few years ago, the Agusta 109 which mnaged an emergency landing as a result a component being installed upside down, the Wessex which lost a main rotor blade on final approach in Nigeria, the Bell 47 which lost a main rotor blade crop spraying in Canada in 1998, the Bell 214 ST which suffered a drag brace failure offshore Aberdeen (I forget the year), the R22 which landed with evere vibration due to a 3 inch crack in the main rotor blade root fitting in 2004, the S76B which lost a one metre section on the inboard portion of one main rotor blade in 2002....... need I go on?

[Bootneck]

Soggy, I remember following Theo L into Unst when he had a huge gap between a wild blade and the other three on his Puma. Makes me smile to remember the happy times. :eek::eek:

[nigelh]

soggy you have mentioned a handfull over a period of 30 odd years and most of them are not actually simple head failure at all . They are a mixture of maintenance failure , and also lightning damage not repaired etc etc Name a few instances of heads just failing on aircraft less than 20 yrs old . I accept there will be one or two but if it were a regular thing that parts just fail people would not get into helicopters !!!!! I have been around them for over 30 years ( as i am sure you have ...) and when i climb into them ( i do choose which ones !) i have very little fear of things just failing.
You will find that when there is a failure there is usually a reason for it .

[soggyboxers]

nigelh,

It matters not one whit whether a catastrophic failure is caused by component failure or maintenence failure, the result is exactly the same for the unlucky pilot. If you care to consult the Griffin accident database you'll find at least 6 accidents in the last 20 years caused by component failures in the main rotor system. I could only find 2 caused by ground resonance in the same period.

[212man]

Nigel,
perhaps you would like to define what constitutes a 'head failure' so that we can be more selective with our suggestions. Clearly drag braces don't count in your book.

How about blade grips? I know of 2 212s that had such failures in the early 2000s. One on short finals to land and which would not have survived more than a few second longer. Or the 332 spindle/blade grip failure on take off from Aberdeen last year (or the one on take off from a platform in the 80s)? Or the KLM S-61 spindle failure in Holland in the mid 90s? What about drag damper failures: are they part of the head? Or the 212 that had a rotating scissors assembly drive nut failure, and promptly shook itself to bits as it fell.

Possibly these don't count as 'head failures' so which specific parts of a 'head' are you referring to?

[Rescue One]

I was at Sheffield airport yesterday, and I think you will find that one of the blades departed for some unknown reason ??. I think this was the first flight after maintenance !!

[212man]

Speechless2,
Yeah, but wasn't a 'head failure', how can you compare that to the Schweizer community? :ugh: (please feel the irony in my comment!:ok:

[ericferret]

Main rotor head failures on Hiller 12e's were a common event. They would crack through the stud holes where the cuff and trunnions mounted. It was a daily inspection item and never lead to an accident on any of our aircraft although the potential was there.

About 10 years ago a 12e crashed in Holland having shed a mainrotor control paddle, part of the head assembly.

What about the Jetranger accidents caused when the TT straps failed. We are still paying the 2 year replacement penalty on that one.

Normally we speak of the main rotor head assembly which includes all the rotating parts except for the blades.

In the case of the S76 this also seems to include the swashplate assembly.

The main rotor hub assembly would normally not include dampers, drag braces e.t.c, but there are so many design variations that it is impossible to have a definite rule.

[Brian Abraham]

Possibly these don't count as 'head failures' so which specific parts of a 'head' are you referring to

Maybe the part between the ears :p

212man, I think you'll know where I'm coming from

[nigelh]

ok fine ..you win ..i was wrong . Head failure is still a common thing on helicopters which makes us either very stupid or very brave :D No not really ...i still think you are talking about a handfull of incidents spaced over many many years. If i didnt know better and stumbled on this thread i would definitely never go in a helicopter again :eek: statistically they are very safe which in itself rules out the myth of huge numbers of failures.
Lastly , i do think there is a difference between a failure due to manufacture or design and one from abuse/poor maintenance. The one i was in was poor maintenance ...i knew it was poor and still flew.....now i wouldnt have got into it . But if you guys want to feel like heroes flying deathtraps ....thats fine by me :ok:
ps it would be good if this was kept out of the press as it would be yet another nail in the coffin.:{

[nigelh]

agree with what you say ....used to do a bit in an Mi 8 in Russia .....every rod/bolt was the size of your arm !!!!! glad you havent ruined my faith in safe helis. ( relatively ):ok:

[contrail]

Thanks everyone.
I had never heard of the phenomena of "ground resonance" before.

[quichemech]

So....

What did actually go wrong with the worlds ugliest helicopter?

[A.Agincourt]

Tell you what - why don't someone phone up and find out? Not hard really is it? Nahhhh that'd spoil all the fun.:}

Best Wishes

[Lokon]

Quich

What did actually go wrong with the worlds ugliest helicopter?


I thought your oppo (AG) worked for them, won't he tell you?

[quichemech]

Lokon,

My oppo as you call him hasn't worked for them for a while as I'm sure you're aware:=

Guess I might have to pick up the phone:rolleyes:

[A.Agincourt]

Saved you the bother - MRGB Failure, precise details NYK

Best Wishes

[Efirmovich]

Well I never, I was joking and nearly spot on ! Must try the Lotto this weekend!! :ok:

E.

[A.Agincourt]

Efirmovich: Post #16 (http://www.pprune.org/forums/member.php?u=134560)

May be the transmissoin siezed and all the blades broke off !!At best I see you might be 50% correct [according to another poster -the blades did not break off] - but it is my guess that that is precisely what you did, guess. Considering you seem unable to use a spell checker at least, I think you were indeed lucky. Go for it - get a lottery ticket and good luck to you.:}

Best Wishes

[OffshoreHeli]

This flying business sounds dangerous. Hope my wife does not read this, she'll be planning a world cruise. Alone!:eek:

[Masterofnone]

Apparently, although this information is second hand, there was a foreign object inside the MRGB........

Possibly a piece of broken tooling?

[ReverseFlight]

This is not an uncommon occurence in the H269/S300 series, being a fully articulated rotor head. I wish I jumped on this thread earlier.

After 2 minutes at 2500 rpm, if you roll off too quickly down to 2000 rpm before closing the throttle, ground resonance can develop, quite independently of the oleos. Snappling the throttle off can upset the hunting interval of the main rotor blades and it only needs one blade out of sync to offset the CG of the rotor disc, hence the violent rocking from side to side.

[VeeAny]

The AAIB published their report last year.

Air Accidents Investigation: Schweizer 269D Configuration A (Schweizer 333), G-TAMA (http://www.aaib.gov.uk/publications/bulletins/august_2008/schweizer_269d_configuration_a__schweizer_333___g_tama.cfm)

[ReverseFlight]

Thanks for the link, VeeAny. Makes very interesting reading.

Glad I wasn't the one at the controls - what a fright.