Wire nut to top of spark plug

[211º]

Anyone ever have this happen when reinstalling the wire to the top of the plug?

[A64Pilot]

I think someone may have overtorqued in the past and fatigued it, I tighten “gentle snug” for the official name

[BobbyH]

Ouch, that is really unfortunate.  @A64Pilot is correct with the fatigue failure.  Could have initiated from over-tightening at some point (probable cause) or a material failure of the nut (inclusions, improper heat treatment, etc.).  So disappointing when just putting things back together.  Hopefully you are able to find a replacement, if not, guess it is time to upgrade the harness set.  And no, I have never seen that on spark plug wire nut.

[211º]

It was literally the last one before a test run-up. Oh well. Time to slow things down a bit I suppose.

[carusoam]

Looks like it may be an aluminum nut?

More easy to over torque and damage than stronger materials…

Prone to cracks and crack propagation… in the high temp and vibration environment that it lives in…

 

Pretty popular device all over the internet… but at $10 each… replacing all eight may be silly…

 

PP guesses only, not a mechanic’s recommendation…

Best regards,

-a-

[Guest]

Some ignition lead wires can be disassembled and new nuts installed, ask your maintainer if he has some spares.  I keep a box of old harnesses just for times like this.

Clarence

[carusoam]

@211º see post from doc above..

 

-a-

[211º]

I briefly spoke with an on-field mechanic yesterday but had to keep it short as I was walking into a meeting. I got the feeling that “he’s see this before” and “we’ll take care of it in your hangar” kind of solution.

I’ll update the post when I return via Southwest on Thursday.

[211º]

The mechanic was able to swap the end, but was a little different in that this harness - Skytronics (?) - had to have the end tapped out instead of (my understanding) of a spring based system.

Anyway, better than a complexly new harness.