P-mag failure / new ignition plan
Deja Vu? Nope, for real. First the factual account:
Sunday afternoon, Tanya and I went out to do some laps in the pattern. We taxied out and did a run-up before takeoff and both ignitions were firing fine. We took off and departed to the east just to get warmed up and comfortable. We came back to the airport after about 10 min. and did two touch-and-gos followed by a full stop. We immediately taxied back to the departure end of the runway without shutting down. We stopped to do a quick run-up as I felt the engine was just a little rougher than normal on the taxi back. When I turned off the left p-mag, we noted NO rpm drop. That was the first interesting sign. With the left mag back on, I turned off the right p-mag (just the P lead, leaving it powered), all ignition stopped. I quickly turned it back on and the engine kept running. I probably should have just let it die. All of this indicated that the left p-mag was not generating spark at all. I shut down that mag and turned off the ship’s power to it at idle. I thought this would fully reinitialize that mag. I powered it back on and it was still completely dead. Those people that are thinking they will be able to fully “reboot” these units in flight as a last resort should take note. Next, I shutdown all of the electrical system and shut down the engine. I fired the engine back up normally and did another mag check. Both ignitions were firing fine. We took off for one quick (extra careful) lap in the pattern. We noted a 50 rpm drop a few hundred feet off the ground on climb-out. Note, in an RV9A, this is barely mid field. Was this the left ignition ceasing to fire? This is a constant speed prop, so the propeller recovered to the rpm set-point. One quick lap and we were back on the ground. We immediately did a mag check, and the left mag was completely dead again. Our day was done.
All of the standard questions and inspections have been asked and done:
- Cooling blast tubes exist
- Timing is fine
- Wires in good condition
- Wires very well supported
- All wiring solid and good (end to end resistance tested). Power, grounds, P (control) leads.
- Switching all sound
- Wiring scheme was originally per Aeroelectric but was changed at last failure per e-mag recommendations.
The rest of the story…
Tanya and I looked at each other without a word and had complete understanding of the situation at hand. I’m so glad she is a pilot and not a skittish passenger/wife. We are done with the P-mags. Just in case you weren’t keeping track, this is the third failure on three separate units. After flying with three different physical units with very similar failures to that described here for the last 98 hours, I don’t feel that they are safe enough for Tanya and I. After the last failure, I told Brad at e-mag that the next failure would be the last time I use their products. At that time, I had a long phone conversation with him about my installation, any suggestions they had, and invited them (in writing and on the phone) to come inspect my application and installation, which they declined.
I have spent enough time and effort (the money is yet to be determined) trying to help them debug these ignitions. I sure wish they had worked out, but my denial is over. It is now time for me to stop messing with P-mags and move on to building a new ignition system.
I talked with Mahlon at Mattituck and have on order one regular Slick impulse coupled magneto for the left side, and one Lightspeed Plasma II Plus with direct crank sensor for the right. I can’t say enough good things about dealing with a reputable engine builder (Mahlon and Mattituck). I told him what I wanted to do and what stuff I thought I wanted to use. He called me back in a few minutes with a fully developed parts list of everything I would need, including gaskets, hardware, and all the little details that I would have surely missed. It is well worth the price to deal with a top notch engine builder. I’m going to use fine wire plugs with the mag on the bottom, and auto plugs on the top with the Lightspeed. This is a very normal setup without going completely back into the dark ages with two mags. I’ll need to pull out most of the wiring for the P-mags. I’ll install new shielded P lead wire for the mag to a switch. I’ll need to find someplace to mount the Lightspeed controller box behind the instrument panel. I have that area pretty full of stuff already so I’m going to have to get real creative with that. I’ll need to add at least one more firewall penetration for the ignition wires going out to the coils. I’m hoping I can get the sensor wires in some other firewall penetration bundles, otherwise they will need another hole. The propeller will come off for the installation of the timing pickup magnets in the back of the flywheel, etc.. It will be a lot of work. The plane will be down probably for a few weeks, especially with shipping around the holidays. I’m just excited to have a new plan and to have survived long enough to be able to execute it. Don’t doubt for a moment that this isn’t an issue of survival. The one thing I haven’t talked about here is my current communication with e-mag. I have sent them a note and will follow through with them, but right now I’m focusing on getting my plane flying again with new ignitions.