At the end of last summer's flying season I discovered that the electric Down and Locked (Robart) landing gear on my Top Flite 1/5 scale P-51C would not operate correctly. They would only retract if the DLE 55 RA engine was running below 1/3 throttle. They worked okay other than that. I spent the next few months trying to find out the reason.
I tested or replaced every part or extension I could think of without any change. I was thinking it might be a vibration problem but no matter what I checked the problem persisted. I finally decided to change the engine ignition. Bingo!! The gear retracted at all throttle settings today.
The picture below shows what I discovered. Where the ignition spark plug wire passed through the firewall the metal braiding on the wire was worn thru. Apparently the hole allowed RF noise to interfere with either the Down and Locked control box or the radio receiver on the retract channel.
I'm posting this in hopes that It might save someone from spending all the time I spent trying to solve a problem that I thought was in the retracts when it was in the ignition instead.
