Bearing fail AAIB helicopter report

[Gragson]

Found the AAIB animation in this news post interesting, the narration and background musak was pretty out of place tho.

Pilot could do 'very little' to stop Leicester City helicopter crash

The crash in 2018 outside Leicester City's stadium killed five people, including the club's chairman.

www.bbc.co.uk

Frightening failure

 

[Wildefalcon]

Always amazes me how short the service life of aeronautical components can be.

 

[Robotstar5]

Always amazes me how short the service life of aeronautical components can be.

They even have a shelf life, I worked with a sparky that used to work on aircraft and he had a cupboard full of perfectly good electronic components, transistors etc. that were skipped from the shelves when they went out of date.

 

[pawsnizzy]

Electronic units on Civil aerospace gas turbine engines have a 50hr warranty

 

[Erie Fred]

There was a number quoted about maint. versus flying.
IIRC a chopper was 3 hours maint for every 1 hour of flying.

 

[daedalusminos]

Electronic units on Civil aerospace gas turbine engines have a 50hr warranty

We give military products one year warranty.

 

[Brad93]

Double Angular contact manufactured by NSN? (not come across them) however it had ceramic balls and a 100% fill!
Also a bronze cage.

Leonardo claiming the bearing was removed and refitted.

Now i don't know about you guys, but on any mission critical equipment, motor, pump etc etc, if we take a bearing off it is replaced.

Certainly makes interesting reading. It's refreshing reading that pilot made no errors and maintenance was as per schedule.

 

[Brad93]

Interestingly Leonardo have now specified a 38% fill on the bearing which is much more conventional.

 

[Hopefuldave]

An improved design would have a pair of thrust bearings on the actuator end of that control shaft so it couldn't unscrew the locking nut...

 

[Brad93]

An improved design would have a pair of thrust bearings on the actuator end of that control shaft so it couldn't unscrew the locking nut...

The stupid thing is, earlier models, DID have a left hand thread! There have been two other incidents in 2012 and 2022 that have been documented with the same aircraft, but they had a LH thread control rod.

 

[grim_d]

They even have a shelf life, I worked with a sparky that used to work on aircraft and he had a cupboard full of perfectly good electronic components, transistors etc. that were skipped from the shelves when they went out of date.

The stuff that gets chucked in the bin is absolutely astonishing.

 

[Hopefuldave]

The stupid thing is, earlier models, DID have a left hand thread! There have been two other incidents in 2012 and 2022 that have been documented with the same aircraft, but they had a LH thread control rod.

So the later revision was quite an "improvement" then... My guess is that the LH thread sheared it off when the bearing failed instead of unscrewing it, so lost control just as effectively.
Hell, I have the nous to failsafe a bloody spring compressor, I'd think a helicopter's primary safety functions deserved a little more thought...

 

[Brad93]

The stuff that gets chucked in the bin is absolutely astonishing.

In a past life i worked in an aerospace sheet metal shop.

We used to make the battery housings for F16, 777's etc

Well we used to make a between 150 and three hundred a month for Leonardo/Selex and at one point i turned round an said hang about we've made over a thousand this year alone for F16s, and there can't even be 1000 left flying.

Yep turns out there was a lifespan and a critical voltage the battery had to meet.

X amount went in the bin a month so they just ordered in batches!!

 

[Brad93]

So the later revision was quite an "improvement" then... My guess is that the LH thread sheared it off when the bearing failed instead of unscrewing it, so lost control just as effectively.
Hell, I have the nous to failsafe a bloody spring compressor, I'd think a helicopter's primary safety functions deserved a little more thought...

In the report one of the incidents was noticed whilst the bird was being run up on the ground.

This is the other