WCT. I would not panic with one coupling not engaging. I noticed it too that one coupling at times does not engage on my engine when slowly pulled through. Especially when the engine is cold. Maybe it is just that. Or it could be that one rivet on the coupling failed, see here an example http://www.sacskyranch.com/eng186.htm But if you say the magneto is new, I rather suspect a sticky coupling arm that will work on higher engine speeds, e.g. when cranking.
Have you mechanic look at it. Magnetos are relatively easy to remove. You'll get the engine retimed that way also. Hartmut From: wctcx3 Sent: Tuesday, April 06, 2010 8:11 PM To: [email protected] Subject: [ercoupe-tech] Bendix Impulse Coupling Went flying last Sunday, and after I put the plane back in the hangar I repositioned the prop to a horizontal position, as I always do so that my hangar-mates won't drag a wing on a prop tip. When I moved the prop I only heard a single "clunk", instead of the usual "clunk-clunk" as both impulse couplings release in sequence. I backed up the prop several times and moved it through top dead center with the same result. Before and during the flight the engine started normally, ran fine, and had a normal rpm drop on mag check. I'm not starting the engine again until I have a mechanic look into this, but I'm curious if any of you have had this problem. By the way, the mag with the problem is only a few years old and has about 200 hours on it. All ADs have been complied with on both mags. Thanks. wct
