Slick mag - impulse not working, what is broken?

[SteveR]

On my left slick mag, the impulse coupling doesn't click and I get a large RPM drop. All four cylinders are firing. Is this a broken impulse spring? Haven't had a chance to open it up yet. The mags have about 500 hours.

 

[bnt83]

Sounds like the impulse spring is broke.

http://www.flight-mechanic.com/wp-content/uploads/2017/02/4-27.jpg

 

[zodiacflyguy]

Pull em both, they are due for inspection anyway. Make sure that all pieces of the impulse coupling are accounted for and none fell into the accessory case.

Sent from my LG-LS997 using Tapatalk

 

[coloradobluesky]

I in the only do one mag at a time camp. That way they don't both fail at once (mechanics do make mistakes you know). I know of several cases where the engine stopped in flight due to both mags failing soon after servicing. Also, you get them out of sequence and service one at 500 hours, the next one at 1000 hours etc (just an example). YMMV

 

[zodiacflyguy]

Understandable, I like to stagger mags as well, like 200 or so hour spread between the two. I have gotten hold of ****ty rebuilds from repair stations as well. I most likely will rebuild my own when the time comes. Of course I am building an aircraft now that does not have mags, rather a distributor with dual ignition points. Seems to be a reliable compromise. The aircraft has delivered 120 knot cruise on about 6gph, and it's aluminum, so no exotic repairs are necessary.

 

[Norman]

Not sure whether I have anything worthy of adding to this conversation but I have seen impulse couplings fail, and at times simultaneously. It's not predictable. Some fail early in their life span, others go the full course and never fail. In my mind, failure is a random occurrence.Ya pays your money...............