Don't forget those "mag" checks!!

[scott heger]

Took a nice flight last week, and upon landing performed a "mag" check (OK, it was a coil check on the rotax 582) prior to shut down. One of the two switch banks was sputtering. I thought I must have fouled one of the four plugs. Never fouled a plug yet, but always a first time right? So next time I go to fly, I replace all four plugs. Start engine up, and same problem. One bank has an intermittent firing spark. Check all the Rotax pin and plug connections and everything looks good. I determined the problem was with the rear coil.

All wires to the coil are connected. I didn't think the coil was bad, because when they go, they are normally dead, and won’t give off a spark at all. I started to pull on the wires that run behind the small oil reservoir for the rotary valve, and the coil power wire separated in my hand just behind the female portion of the bullet plug (the red and white striped wire). The wire had broken internally and was being hold together only by the outer insulation. I rigged a jumper wire to confirm the problem, the engine ran well again. Replaced the female bullet connection and I was off to San Diego County for a great 2 hour flight today.

The important part: DON'T forget to do those “mag” checks at the start and end of every flight. Nothing like a dual coil system to save your bacon, when you didn’t even know it needed saving.

Scott Heger Laguna Niguel, Ca N86SH

[CLS447]

Scott, thanks for the advice. I do wished that I had the DCDI .

What caused this wire to fail? How could this have been prevented?

[scott heger]

Chris,
I don't think there was anything I could have done to prevent the problem. THe wire was never touched, it runs in a lined black plastic tube behind the rotary valve oil tank. It broke less than 1/4 inch behind the female bullet connector. The engine has 200 hours on it. My guess is that it was "doomed" from the factory. The connector is two parts. One part that clamps the bare wire near the bullet head, and the end of the connector clamps to the outside of the wire. This was the area it broke in a clean straight cut. My guess is a little too much clamping at the factory weakened the wire. The outer insulation was still intact, so it sure was not streached by anything that I did. You could do the most perfect annual or daily inspections, and would never have caught the problem. Just one of those things...Thats the reason once the engine is running the individual coils are checked, if they don't pass , no reason to tempt fate. It just was not my time for a engine out (at least on this flight).

Scott Heger, Laguna Niguel, Ca N86SH

[KenSandyEggo]

I have 2 ignition systems on my Soob with separate switches and can check each individually. What I also did was avoid the temptation of using one tachometer for both. I installed two, one for each ignition. At least I have some indication of an ignition failure on either of the systems while inflight. This precludes having one go out right after take-off and flying unknowingly for maybe hours on one ignition system. I leave both running all the time.

[StanFoster]

Ken: Good idea on the dual tachs.

[KenSandyEggo]

I have a lot more Stan, but when I mention them, Dr. Bill sends me a crate of pills to take.