SonexBuilders.net

So I am here now I am performing my first condition inspection and I discovered that the wiring to the bottom magnetron has been compromised by a hot exhaust pipe! How hard is it to change out with the engine still on the engine mount? I must replace due to the burn thru the insulation.

On the Sonex airframe it was not too bad to change a Magnitron on the bottom while the engine is mounted. I would not expect a Onex would be much different. The only two challenges are: 1)accessing the nuts on the inside face of the Accessory Plate when you are reinstalling the Magnetron; and 2) Setting the correct gap between the Magnetron and the trigger. Other than those two tasks everything else is the same as when you installed them initially. The only difference in these two tasks is visual, finger, and tool access is a little more limited but doable. I would definitely attempt it before you decide to pull the engine.

You may need to loosen the intake manifold Y pipe and remove the AeroInjector for better access.

Jake

A hemostat is very useful for this task. It is a good way to hold the tiny nut in position.

https://www.amazon.com/hemostat/s?ie=UTF8&page=1&rh=i%3Aaps%2Ck%3Ahemostat

Detlev

I also had the same thing happen. You can remove the spark plug wire from the ignition module. The wire is glued into the module and there is also a screw stud in the hole that the wire goes in. By forcefully twisting and pulling the old wire will come out...you may also need to dig out some glued in insulation. I replaced my wire with a Ford tractor spark plug wire that had a solid copper core. Bought a set of wires on Ebay....the tractor wires were the correct size to fit the hole in the module.

Thanks to all the advice as to the replacement task of my magnetrons...SUCCESS! After looking county-wide for a 7/32 Ignition Wrench (thanks Sears for having these) I began the task. Removed the intake manifold and aeroinjector. Had to figure out how to hold the ignition wrench with sausage fingers, spend time looking for the hex nut that decided to take up residence somewhere in the back of the flywheel, yada-yada-yada. Two well spent afternoons to get it correct. A little grinding on the top mag. Took apart and repositioned the shim, problem solved. Prop turns smoothly. The real test will be if it fires up as it use to. But for now, waiting on my K&N E3120 filter and reworking my fuel lines to include a fuel strainer (no gascolator). Then back to completing the condition inspection and continuing Phase I.
Hemostats were definitely a big help (Thanks for that tip).

I'm curious as to the best way to connect a ground wire to the magnetron. I haven't found a female terminal that fits well as per the suggestion in the Sonex manual. Any ideas?
Peter

I think I squeezed the female spade terminal with pliers a little bit. We also did the same thing on the B&S powered hovercraft we built.

I couldn't find a fast on terminal that would fit on the stud. I noticed there is a small threaded hole thru the top of core I'm wondering now if anyone has used that to ground the ignition module and if so what the thread size is. I want to avoid putting an eye terminal on the mounting screw ...getting that screw out and back in will be difficult.

My understanding is to disable the ignition, you must short the terminals of the internal low voltage coil together. One of those terminals is connected to the tab and the other is connected to the core, so whatever solution you use must involve the tab. I also crushed the terminal a bit to fit, but it isn't a super satisfying connection. I believe the coils include a female terminal already crimped to a wire--I imagine that one is the correct size.

Just finished my second test flight yesterday and while my turbo engine seems to be running fine when I tested the mags at idle (turned off the 12V ignition) taxiing back to hangar, the engine died. Restarted immediately on 12V ignition. Tried another time with same result. Seems odd that both mags would apparently fail simultaneously but that appears to be the case or am I missing something. Anyone have any thoughts. I'll email Kerry on Monday.

Tom Jones
Onex 0133
Aerovee Turbo