PPRuNe Forums - UK AAIB(H) June 2008

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UK AAIB(H) June 2008

AS332L nosewheel locking pin engages inadvertently during taxi, aerobatics on the ground before the crew rein it in - here.

R22 heavy landing off approach to hilltop site - here.

R44 fails to make it to destination in poor weather - here.

Steve

I read only the L2 report. Interesting and we had something a bit like that many years ago in BHL. But very sorry to see that the standard of the report is so bad. For instance:

Quote:

During a ground taxi, the crew felt a control restriction
when attempting to turn left and realised that the nose
wheel locking pin had become engaged.

No, there was no control restriction, just a lack of apparent effect from the control input.

Quote:

The nosewheel locking pin, when engaged, prevents the
helicopter’s nosewheel rotating

No - that would be a brake! - the nosewheel lock prevents it from steering. I suppose you could argue that its talking about rotating in a different plane, but how misleading is that!

Quote:

The flag will drop as soon as the
lever is rotated, even...

No, the flag drops when the lever is pulled up, not when its rotated.

Quote:

The locking pin is released by rotating the lever and
pushing it down, causing a spring to force the pin out of
the hole and allowing the body of the nosewheel to rotate
freely.

No, a spring does not force the pin out, its the force directly from the cable / lever.

Quote:

The forces exerted on the aircraft
by the application of left yaw pedal whilst the helicopter
was unable to turn would have created a rolling
moment, exasperated by the increase in collective pitch
application.

No, exasperated means "greatly annoyed; out of patience" or whatever. Perhaps the author meant "exacerbated" or similair?

And no real comment on the potential safety hazard, especially the risk of rollover with accompanying destruction of the helicopter and possible death of bystanders, that can result from excessive yaw pedal application on this type of helicopter. Such excessive pedal input is typically induced by the helicopter's failure to turn eg when the nosewheel lock is in.

Come on AAIB, you are rightly world renowned for integrity and competance. Don't let your standards slip like this!

HC

Thanks for the links Hilico.
Really sad to read the R44 report, every year the same... :sad:

Quote:

The commander stated
that he increased collective pitch with the intention of
reducing the pressure acting on the pin, so that it could
be released. In doing so he felt the helicopter become
unstable and so continued to lift it into the hover, this
being done with the Automatic Flight Control System
(AFCS) disengaged. The helicopter rolled and pitched
before it could be brought into a stable hover where
the AFCS was then engaged by the commander using
the engagement button positioned on the cyclic. The
helicopter was hover taxied the rest of the way to Spot 3
where it landed safely

I had a similar experience when taxiing over a taxiway light, the helicopter en/up in hover without AFCS, with some PIO (like in this case I assume) .
I prefer to engage the AFCS if collective is going up, even for a short taxi.

Regards
Aser

Does make you wonder how (if?) these reports are checked before being issued.

I half feel like apologising for not proof-reading it first! All I do is look at the summary, condense it into a one-liner and post. Really, the standard of English is most exacerbating. Must do gooder.

That R44 crash should be used as a case-study at the safety evenings - it is a classic 'pressonitis' scenario where at any stage the crash could have been avoided by landing or turning back. Very sad waste of 4 lives.

Crab

You are quite correct and it is, we have a contact at the AAIB and he has assisted (as far as he is permitted) with some of the content and photos we use at the safety evenings.

GS