Might want to check


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Well-Known Member
Feb 10, 2007
Sopchoppy, Florida, USA
Visited a friend this afternoon. He was taking his motor off. Seems he had a spate of trouble and returned to his home field for a Precautionary Landing (PL).

Good thing he did! Counter sunk screws holding his fly wheel, alternator and center spindle had backed out.

First picture shows fly wheel on top, alternator below that, and what I will call the spindle on the right. The spindle is what holds it all on. All that dust is from the metal shaved off getting home!

The fly wheel holds the magnet that triggers the ignition. He first noticed something wrong when performance on his full VW dropped. With the fly wheel loose, timing would wobble around.

The alternator has been worn down to where the copper wire shows. Obviously, it would have not lasted much longer! He did not notice electrical problems, just a fine something appearing on his wind screen.

The second picture shows the end of the crank. Note the areas of missing metal around 3 of the threaded holes. We don't know whether to trust the flange - could be that die penetrant would show nothing.

The Diehl accessory case he has allows viewing of the screws. He is adding a visual check of the screws on every oil change. I'm gonna suggest some "Torque Stripe" to assure things have not moved.

Don't know how many hours in service, and I am posting this as a caution point for those it may be of interest to. PM me for details, though I don't know when I'll see him next.

Percy in SE Bama


Last edited:


Light Plane Philosopher
HBA Supporter
Dec 16, 2007
Port Townsend WA
He should check his prop torque. A loose prop can do that.
I saw a sheared flywheel on a Jabiru. The owner neglected prop torque. The wood prop was removed and the face was charred, which is caused by friction from loose bolts.