Wednesday, May 16, 2012

Magneto problems solved

Yahtzee!

We finally got it figured out.

The timing pin from AS arrived today so back to the problem I went. I had already determined yesterday -- using the paper clip method -- that the mag was generating a spark on the #1 tower. So I sparked it and then backed it back to insert the timing pin (I don't know if it made any difference but in previous insertions of the pin last Sunday, we didn't trip the the impulse coupling).

I had already used the the Rite System kit I bought a few weeks ago to find TDC and backed the prop back to 25 degrees TDC (all plugs removed), then carefully reinserted the magneto and clamped it down. The amazing Brad Benson helped time it, and we reinstalled all plugs and reconnected the ignition wires (after determining that the #1 sparked via the ignition wires to eliminate them as a cause of our woes).

Mike Hilger, who had just done by transponder check, joined us and we rolled it out and started.

I tend to think flooding the engine on Sunday was a source of a lot of our problems so I returned to the Mattituck method and she started right up. No kickback.

I brought the Lightspeed online but with the plane wanting to move -- the brakes having not been broken in yet -- I didn't like the orientation of the plane relative to a nearby hangar so shut it down without checking RPM etc.

We straightened things out and I restarted on the mag and everything looked good. I brought the Lightspeed online and then killed the mag -- and the engine started to stop. ARE YOU FREAKIN' KIDDING ME?

Have I just exchanged one problem for another??? Criminy!

Multiple retries, resetting the circuit breaker. Nothing.

At Brad's ingenious suggested. We took the Lightspeed ignition wires off and checked the phase. Now, we'd just this a couple of weeks ago and when we rocked the prop at TDC of the #1 cylinder, we got a nice spark arcing on the 1/2 coils.... and 180 degrees later, we got an arc on the 3/4 coils.

As we moved the prop to TDC on the #1 cylinder tonight, however, we got an arc -- on the cube for the 3/4 cylinders. What the heck? How could this be. We not only got a proper spark when we did this a couple of weeks ago, we actually started the engine on the electronic ignition. How could this be?

Answer? We don't know. But we just swapped the ignition wires on the lightspeed to the opposite cubes and it started up fine on the mag, the Lightspeed was brought on line the mag was taken offline and she kept on purring.

So now we were back to where we were when we first detected our problems a couple of weeks ago -- about to break in the brakes and check the static RPM.

I wasn't happy with how the brakes were working but -- surprise -- I taxied up to the ramp at KSGS at 1700 RPM dragging the brakes and they then started working fine.

I turned the plane around on the taxiway and then tested the other thing that we wanted to do when we started this process -- the RPM. I'd swapped out a larger throttle arm on the Precision Silverhawk with a 2" throttle arm. It worked beautifully.

Almost fully pulled back, it idled around 550 RPM. Then I gave it the gun on the taxiway and about halfway in (or so it seemed), I was at 2150-2200 RPM. I considered that good enough so I pulled power, taxied back to the hangar and shut it down.

The thing is: I don't know EXACTLY what we did to solve this problem other than just start over again. It seemed to me there wasn't really anything we did that we hadn't done before, but maybe just starting over was the way to go.

Many thanks to Brad and Mike and Tom Berge and the gang on Van's Air Force for their help.

I think we can go ahead and call the DAR now.

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