Microlighters

Sadly I had a gear collapse on my Bushbaby that resulted in a prop strike that destroyed my wooden P Prop. The aircraft was taxiing at walking speed and the engine was running at approximately 2500 rpm. One blade broke off completely about half way along it's length and the other blade splintered quite severely. There does not appear to be any exterior damage and the engine can be turned over normally.

I don't want to get into the cause of the collapse but would like advice on the likely damage to the engine and gear box. Is the engine protected by the gear box and can the gear box sustain this sort of shock load because of the rubber couplings in it? Both the engine and gear box have only about five hours on them. Will either or both items have to be opened up for inspection?

Thanks

Johnny

Hi Johny

I do not think that there is any guarantee that you will not have any damage, but I doubt it, just after I went solo my trike goose stepped and I flipped it upside down, the engine was running at full throttle and it broke all 3 blades on the Ivo prop without any damage to the engine or gearbox, and I know of several other people with similar mishaps without any damage to engine or prop, but as I said there is no guarantees, if it was mine, I would take the chance.

Hi Johnny Be Good - sorry to hear about your incident - I also have a Bushbaby, so maybe you can pm me sometime on the circumstances. However, my instructor ground looped my plane, smashing the prop amongst other things, although I have a 912. After speaking to Aviation Engines / Comet Aviation, they suggested that I put a dial gauge on the output shaft, and if it was within spec, they said that there was then nothing further that needed attention. As for the tortional stress, that is one of the reasons for the rubber coupling, so I believe you should be OK, but for peace of mind, speak to them and get their mechanic's opinion.

Thanks Kalahari, I had similar advice here too but I will also contact Comet as Dobbs suggests and get the allowable specs to check if the output shaft is still in alignment. Cheers

Another E gearbox.....

Hi Dobbs

Does the 912 rotax not have a slipper clutch to minimise damage to the gearbox and engine (crank) in a prop strike.

I think I can recall that 912's have these but I may be wrong

regards

Hi Sukkelaar!!!!

Yes, the 912's do have slipper cluthes, but this takes care of the torsional knock, when my instructor ground looped mine, the undercarriage collapsed causing a vertical load on the output shaft, hence my concen about runout - but fortunately all OK

This is the same problem that I have with my 582. Although the motor was turning relatively slowly, the vertical force of the gear collapse was enough to bend the engine mount. I have opened up the front cover of the gear box and it all looks okay but I haven't measured the run out yet.