Impulse Coupler
Apologies if this is the wrong forum for this, but it looks like there are technical questions here...
Recently had a flight cancelled as after startup we noticed a catastrophic mag drop on one mag, with some rather alarming misfire. The engineer who fixed the problem has diagnosed an impulse coupler failure on the mag in question.
What would cause this to occur? We'd just landed from a flight over the Irish Sea for some fuel and it happened when we were due to depart the airfield. Were we on the lucky side that it didn't occur during the crossing, or would starting the engine have caused the failure?
I've read up a little on the impulse coupler. How could it fail mid flight, as it doesn't seem to engage above 250rpm?