Lots of experience of ring gear failure with Enstroms. Mine is on its seventh. (its 29 years old). Looking through the log books it has been a problem all its life so its not likely to be pilot induced or a batch production problem. Enstrom is Bendix fuel injected with Bendix mags which I think is the same as a Raven 2. Enstrom starting procedure exactly as described above.
I assume the R44 uses 2 sets of contact breaker points.
Mode of failure is ususally when the engine doesn't fire until the instant the switch is released. What then happens is that the advanced cb points are then activated causing the engine to fire. If there is not enough momentum to carry it over TDC, the engine will rapidly revolve in reverse for half a revolution. If the starter motor gear is still egaged, something breaks. Ususally its the ring gear but can be the starter motor casting. Ive even had it chew up the sprag clutch in the starter motor.
The next time the starter is tried there is a gnashing of gears. Very unpleasant.
As the starter drops out of mesh with the ring gear pretty quick, it can only happen if the button is released at exactly the moment the advanced points open. This is why it doesn't happen very often.
There is an unauthorised fix for this by putting a switch to hold the retard points on until the engine is actually running but as far as I know there is no authorised fix for this.
Its worse for helicopter engines than fixed wing as the belt drags a bit and there is arguably less flywheel effect. (no prop)
I don't believe it is a problem of wrong starting procedure. It happens if you are unfortunate enough to release the starter at the wrong time, which you have no way of knowing. Crap design.
You gotta live with it.
Gear failure can also be caused if the relay that switches to to retarded points fails but that is not likely in a new 44.
Pushing the start button with the engine running is not good either.
Last edited by Gaseous; 2nd Feb 2005 at 21:34.