Posting this here because many people here own aircraft equipped with Slick-style magnetos, and this affected me personally (twice!).

The very short version is, I have had two separate serious failures of Champion Impulse Couplings in the past 2 years, with only 110 and 82 hours on each, respectively. Both failures were so catastrophic in nature that they damaged the accessory drive gears in the engine and required a full teardown inspection of the engine.

The most recent failure stranded me and my Mooney in South Dakota for 6 months. Luckily, both of these failures happened on the ground, but it is not impossible for an in-flight failure to occur, which could result in a total engine failure, which is why the FAA is pursuing an AD here.

I have been working with both Hartzell (who owns QAA, the shop that overhauled my magnetos) and Champion (they produce the impulse couplers). I've also been in contact with the gentleman from the FAA that produced this notice, since he is investigating an identical string of failures in the DC area. My first failure was covered by QAA (as a 'warranty' issue), however in retrospect it was clearly not their doing. Thus far, Champion has denied that there is a problem with these couplings.

In case you haven't had an engine shop teardown an engine recently, this is no small cost. I am well over $40k (conservatively) out of pocked on these and have had 9 months of downtime.

If you fly an airplane equipped with such couplings, it would be good to consider your options. I have switched to an electronic ignition to eliminate my impulse couplings altogether.