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Hey Guys, take a look at your plastic connector to the R/R. I found a bit of overheated wire on one of the three phase wires coming from the PMA. You can see that it discolored the connector area where the spade associated with the bare wire is located and seated. That bare wire is the one that overheated and made it easy to crack and break off the insulation. It also got hot enough to partial melt some of the other phase wires. Crimps are all good, output wires good, so I'm scratching my head a bit on why this would overheat. One of the A&P/IA mechanics I work with thinks it is most likely due to the fact that I had applied some dielectric grease to the terminal connections during install. Evidently, a big "NO-NO" and certainly not recommended. I am currently (bit of a pun there) still investigating that on the Matronics Aero-Electric forum with the electrical gurus. So, be heads up, pull those cowls and take a look at things pretty close every couple hours.
Wow David, could this mean there was very high resistance at the connectors? I wonder if that is why my prewired connector was so tight I couldn't remove it.
Certainly looks like things got HOT there. Good catch on the inspection.
My connector burned last week and I just received the replacement from Wicks. This appears to be a larger problem and I talked to Gary Motley and Ray Lawrence about it and they also suggested putting dielectric grease to the connection, especially since it is not water tight. The burn was only on the Stator wires and I also did some reading (on Motorcycle pages) where crankcase oil can seep its way into the wire and reach the connector which could case a short and burn. I am getting frustrated as I just finished the Muffler repairs and now it is another thing to keep me from flying!
Scott, hang in there..I've pulled my engine twice so far this year (LOL) The interactive mx manual shows how to mark the wires with a sharpie to validate good seating of the terminals within the connector and R/R. I also fashioned a small flat push tool to ensure the terminals were seated by pushing the terminals from and thru the rear of the connector shell onto the R/R blades. While I was changing out that particular connector, I elected to upgrade the output wires to 10 ga. as well and put fresh heat past under the R/R. No issues since with about 100 hrs accumulated.
Rotax suffers the same problem. Another thing that is recommended is to secure the wire bundle as close as possible to the connector. This will keep it from slowly walking off due to vibration, and insure that the connections remain well seated.