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While searching for possible causes of a recent radio noise issue, I read that the alternator connectors are undersized, and prone to heating. It was advised that the connectors be removed, and the wires be soldered instead.

I thought that this would be an easy enough project until I removed the silicone tape I had wrapped around the heat shrink sleeve. It appears that my attempt to insulate the connection may have held in the heat, and it got hot enough to melt the heat shrink tubing:



The wire insulation melted, and there appears to be signs of arcing:


I've also read that the voltage regulator connector can get corroded, and begin to arc -- which causes noise. I checked mine not too long ago, and it looked fine, so I'll leave it be unless the alternator wiring change doesn't resolve the noise issue.

Keywords: terminals, connectors, melting, wiring, alternator, electrical, arcing, arc, noise

Very common problem. Those spade lug connectors have been undersized since day one. Just replacing them with good quality auto spade lugs of same size, rated 30 amps is sufficient, or can just solder the connections. Replaced mine with good quality ones on first installation, no problems. Looks like you should replace connectors on both the alternator and regulator on yours, can be individual connectors, no fancy multi-connector needed. Make sure wire insulation is still okay, may have to cut leads back a bit to get to insulation that is not over cooked and is still flexible. Doubt if your shrink sleeve contributed much to the problem.

David A. Jabiru 3300, (retired) and CAMit 3300

Don’t take this too lightly- I did.

In 2011 I was sitting up there, dumb, fat and happy, as the saying goes, watching the beautiful scenery, at peace with myself and the world- when at 2700’ agl the oil pressure went to zero. We all know about the mind blowing quality of the pressure senders, so this in itself would not be a show stopper, I reasoned. More disturbing was that acrid smoke started to enter the cockpit: fuel and switches to ‘off’!

I almost managed to glide back to the airstrip- almost, because I went into the bushes about a quarter mile before the threshhold. There the Sonex lay smoking until the firetruck arrived.

Post crash investigation revealed that the connectors had shorted against the alternator bridge, causing the insulation of the leads to the rectifier to melt, which again started a fire in the rest of the wire insulation. It quickly spread to the rest of the electrical system: the zero oil pressure was caused by the insulation less sender wire shorting against the crankcase.

Lesson learned: do not use substandard connectors, and shy car type wiring as the plague: stick to aviation grade Tefzel.

You cannot believe the extent of the following clean up work under the cowling- not to mention the 13 months to get the airframe back into shape.

As said- don’t take this too lightly.

Thanks
Kai

Thanks for the advice. I already soldered the alternator connections, and will now upgrade my regulator connections.