Starter not disengaged

[Dan Thomas]

I think it's virtually impossible for the starter to remain engaged on a running engine and if so there would be some major racket before substantial destruction. I'm not sure what the gear ratio is but probably at least 10:1 so at 2400 rpm the little stater pinion would have to spin at 24,000 rpm. That wouldn't last for long if it even made it that far.

Even if the gear stays engaged, it has the one-way clutch behind it so the starter doesn't over-rev.

Once had an R182 (Lycoming O-540) where the light Bendix return spring had broken. I heard a tinkling noise as the airplane taxied up. The starter gear was touching the ring gear.

Now, if that Bendix spline has been getting oiled instead of the dry silicone lube, gunk will build up and that starter drive can not only get reluctant to engage, it can get reluctant to disengage, too, and so you'll get a terrific racket from the Bendix ratchet, the one-way clutch. That's the thing that makes the clicking noise if the drive is engaged and you turn the prop in its normal direction. Turning the prop backward will spin the starter.

 

[Domenick]

I think it's virtually impossible for the starter to remain engaged on a running engine and if so there would be some major racket before substantial destruction. I'm not sure what the gear ratio is but probably at least 10:1 so at 2400 rpm the little stater pinion would have to spin at 24,000 rpm. That wouldn't last for long if it even made it that far.

When my bendix failed to disengage, the racket made me shutdown immediately. RPM didn't get above 1000. No damage to starter and no damage to ring gear. I replaced the bendix, and the starter is still operating well.

I cannot imagine anyone taxiing, running up, and taking off with that racket.

The Lycoming Prestolite bendix gear has 9 teeth. My ring gear has 149 teeth making the ratio 16.6:1.

 

[Dan Thomas]

I cannot imagine anyone taxiing, running up, and taking off with that racket.

Not with a Lycoming. Lots of noise there. In a Continental you won't hear anything at all unless you're hearing is sharp enough to hear the starter itself still running due to a stuck starter contactor. The starter drive makes no noise. In fact, in the small Continentals, with the key start (not the old cable pull-start), that starter drive gear is engaged all the time. The Bendix lets it slip.