Hmmmmm....lots of stuff here....but the missing bits seem to be:
What is a ring gear - a gear (usually attached to the flywheel area) that the starter motor engages with to turn the crankshaft of the engine during start up
What happened before/after failure - since close to new and during start up the starter motor would occaisonally fail to engage with the ring gear. this made a sound like high pitched whizz...rather than the usual aruuuugha during a normal piston engine start.....usually stopping the start procedure and waiting about 30 secs remedied the situation.....this happened more frequently until the engine failed to start at all.
What happened - the ring gear had big chunks out of the side of it and rounded teeth in some parts...I will try to recover the failed gear and get some pics....as a matter of interest one of the machines being repaired was from Brisbane....a long way from Sydney so with different pilots....
What is the required starting procedure - of course this is in the manual....but my take on it is (check this with your engineer!!!)
Main switch on
Area clear
Throttle closed
Mixture full rich
Prime (cold engine 6 secs, warm engine 3 secs)
Mixture full lean
Press starter button on collective with left hand
As soon as engine fires release starter button
Quickly feed in mixture to full rich with right hand
Alternator, clutch, oil pressure, etc
The important thing (according to my engineer) is to ensure that the starter is released BEFORE feeding in the mixture rich lever.....
I am still interested if anybody else has had similar issues as I am having difficulty understanding how the damage I obsered was caused by the starting sequence.....
PC