News Red Arrows ejector seat firm guilty over RAF Scampton death

[Notebook]

An ejector seat firm has admitted breaching health and safety laws over the death of a Red Arrows pilot.
Flt Lt Sean Cunningham, 35, was ejected unexpectedly from his jet while it was on the ground at RAF Scampton in 2011.
But the parachute on the seat did not then deploy and the South African-born airman was fatally injured.

http://www.bbc.co.uk/news/uk-42773834

Flt Lt Cunningham's parachute failed to deploy because a nut and bolt had been fastened too tightly.

Can't be the whole story. Torque-wrenches have been around a long time.

N.

 

[MaverickSawyer]

As someone who is going through aviation maintenance training, it could be that simple. If the maintainer doing the work became complacent due to the task becoming routine, he may have fallen into the "calibrated elbow" trap: "I've done this hundreds of times before. I know what 50 inch-pounds feels like." Without fail, in situations like that, mechanics will over torque the nut, usually by about 25%. The Federal Aviation Administration has done studies on this time and again. Hell, I've personally seen how easy it is to over torque something if you're distracted or using an unfamiliar tool.

 

[Urwumpe]

Fastened too tightly usually means "destroyed" in all mechanics dictionaries. I don't want to know how much money the car industry alone earns by people destroying their wheels and/or cars by overtorquing the bolts.

 

[Andy44]

I'm interested in what kind of a parachute mechanism depends on a single nut and bolt not being overtightened; doesn't sound like a robust system to begin with.

Then there's the unintended firing of the seat. Surely something or someone failed there. Ejection seat are necessary to save aircrew, but they are also scary dangerous devices if you don't know what you're doing or don't pay attention.

 

[Urwumpe]

Well, read here, the full story is a bit more complex than the news put it:

https://www.gov.uk/government/publi...y-into-the-accident-involving-hawk-tmk1-xx177

The bolt that failed was supposed to release the drogue from the ejection seat and make it pull out the main chute. By overtighening it, it did not release, because the drogue shackle was compressed too much.

See here, page 36:

https://www.gov.uk/government/uploa...data/file/277777/XX177Part_1_4_2_analysis.pdf

 

[C3PO]

IMHO that's a design flaw.
This is the first time I've seen a shackle that wasn't using some kind of recess to tighten the nut or bolt against. Using the "bend" of the shackle to tighten the nut/bolt against is a big No-No in my book. Any deformation of the "bend" would loosen the nut. Using the thread as a bottom stop is even worse. :facepalm:
:2cents:

 

[Evil_Onyx]

I've read the full report, the seat had not been in a safe state for 4 days prior to the incident due to the safety pin not been inserted correctly. Page 18~

The drogue shackle was not fitted correctly, the Maintenance procedure did not specify how (and how not) to tighten the nut. Also of note is that if ejection had occurred at over 50 knts the seat would probably operated correctly, according to testing that was performed. Page 40

The pilot was self medicating, had to be reminded to remove the safety pins, and most likely inadvertently triggered the ejection due to the handle been out of position.

In summery, the RAFAT did not keep personal qualified to do the jobs they where doing within the squadron (including pilots), Martin-Baker and BAE failed to tell there customers that there may be an issue, the MOD failed to provide proper documentation for AC operation and maintenance. And record keeping was bad for all involved.

 

[C3PO]

I've read the full report...

Oh, I didn't have time to read the whole thing. (I'm saving that for later) I'm sure the shackle was at "best" a contributing factor. I'm just saying that the shackle was a bad design. Especially fig.45 p.37 looked really wrong to me.

 

[Notebook]

i don't understand that shackle and scissors arrangement, surely the bolt should have a sleeve on it to stop the lugs closing? Its basically a "C" shape, and bound to close up as the nut is tightened.

N.

 

[Thunder Chicken]

From reading the report it seems that the maintenance guidance was lacking. The fastening of the nut was in accordance with the published technical procedure with no torque specification given.

 

[MaverickSawyer]

Failing to specify a particular torque is no excuse. There are standard torques for each size and thread pitch of bolt in aviation service. Heck, I used that standards book in class today.

 

[Notebook]

An ejection seat manufacturer prosecuted over the death of a Red Arrows pilot thrown from his jet has been fined £1.1m.
Flt Lt Sean Cunningham, 35, was ejected while conducting pre-flight safety checks at RAF Scampton in 2011.

http://www.bbc.co.uk/news/uk-england-lincolnshire-43171049

Nothing here about how they are going to prevent it happening again.

N,