Sunday, 17 October 2010

an EXTRAORDINARY engine failure

the offending nut - well mallered!

see description below

pitting in cylinder head

goughing in the top of the piston

I had the privilege of being present, today, at the post mortem of Neill Howarth's 912, 48hrs after he brought himself and his student safely down, after it shuddered violently and stopped on take-off.

Amazingly, it turned out that the nut which held a cowl over his air filter's heater had vibrated loose and was sucked through the carb, through the inlet manifold, through the inlet port and was trapped between the piston and the cylinder head, where it was hammered violently. We think the washer must have broken up on the filter cowl bolt, easing the nut so that it wound free...and that the bits of washer got caught in the carb (where we found them). Some debris went into the rear cylinder head too with less catastrophic consequences. The gouging and pitting in both the starboard cylinder heads, just near the valves, and on the pistons is very clear.

It is hoped that the cylinder heads can be cleaned up, the pistons replaced and stress testing done...and that these steps alone will put things right. It could have been a hell of a lot more expensive.

No comments: