Surefly...impulse coupled or non?

[mr_happyland]

Both of mags have enough hours on them that I'm considering swapping one our for a Surefly and replacing/overhauling the other. I'm hearing differing opinions on which one to swap out with the EI. This would be for a 24v AG5B. Enlighten me with your opinions. And yes...I'm aware of the previous Surefly issues on 24v airplanes. That issue has apparently been resolved with their last revision.

 

[simtech]

Their website, under FAQ, recommends to replace the impulse coupled mag. I have it on my plane with over 125hrs on it and doing well. I'll put a second one on when they approve it.

 

[Kevin Holbrook]

I replaced the impulse coupled mag on the left side of the O-360-A4M on my C172N. I had an impulse coupling break and leave me AOG. It could have been worse—they can grenade and put metal in the engine.

what I did different was to buy the NON-impulse SureFly, which allowed me to remove the impulse spacer (had to replace the mag studs with shorter ones). This gave me more clearance between the engine and the battery box. On the Air Planes 180 conversion, the engine mount is shorter for W&B purposes and it’s really cramped behind the engine.

The impulse and non-impulse SureFly function identically, the “impulse” model just has a longer nose to account for the impulse spacer.

I have been very happy with the setup.
I did have the 24v issue. Apparently my VR was allowing voltage spikes, usually on climb out. Brief loss of about 100 rpm. Really gets one’s attention. a friend flew my plane and managed to take of on the left mag only. The engine cut off for about 2-3 seconds 100’ AGL. Problem fixed now with the SureFly conversion kit.

I go back and forth about replacing the other mag. I love the performance and no maintenance of the SureFly, but the old reliable “1930’s tractor technology” magneto with no external power requirement just works.