O.E.M. Instructions or lack of.

[MCN]

https://www.ioshmagazine.com/article/martin-baker-fined-ps11m-red-arrows-pilots-fatal-ejection-seat-failure

I was living in Hull when this tragic event happened.

Since MOD a lot of the details are or were eyes only. (It's sort of normal for that industry.)

The details and root cause are very interesting as far as maintenance procedures are concerned.

People really need to understand exactly what is expected of the equipment they work on and rely on.

£1.1 million is not much. I bet if it was in the US it would have been much more.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[stinkwheel]

So an RAF technician caused this accident by overtightening the release shackle to the point it deformed and couldn't separate.

Manufacturer was fined because they were made aware that someone could overtighten it and didn't insert a phrase in the UK issue users manual telling them not to.

Crying shame.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[MCN]

[stinkwheel]

Military engineers have a long history of overtightening stuff. The unofficial moto of the Royal Electrical and Mechanical Engineers (REME) is "Tighten it 'till it strips them back it off half a turn so you don't get the blame.".

I'm not up on the units used. How much extra force did they actually put on the fastener to deform it so much it was no longer a sliding fit?

"technician overtightened the locknut on to the bolt of the drogue shackle to 1.5 threads."

So does that mean 1.5 turns too much? I wonder if there were instructions as to how tightly it SHOULD be done up to, either by angular tightening or torque. You'd have thought there would be a pretty strict specification in this regard with an application like that? I wouldn't be surprised to find there was and it was ignored. The additional advice being just that, additional.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[weasley]

I read the accident report a while ago. The overtightened bolt was the reason for non-deployment of the chute, but there was also an ineffective and/or badly-fitted safety pin in the ejection seat that meant the seat went off in the first place. From memory, the pre-flight check involves checking the ejection handle is secure - the errant locking pin allowed the handle to move enough to initiate the ejection. This should have been survivable but then exposed the over-tightened clamping bolt. Classic case of alignment of factors. Really sad loss and only 3 months after another Red Arrows fatality at Bournemouth.
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Yamaha XJ600 | Yamaha YZF600R Thundercat | KTM 990 SMT | BMW F900XR TE

[MCN]

[stinkwheel]