Old timer vs. digital: who's right on wire testing?

I had a guy named Frank at a shop in Kansas City swear up and down that a megger test on a bundle of wires is pointless unless you've baked them in the sun for an hour first. He said the moisture hides until the heat pulls it out, and I thought he was full of it until I saw a harness pass cold then fail hot on a Cessna 172. On the other hand, my current lead says if it passes the first time, move on and don't waste shop time. He's all about the digital tester logging results and walking away. Which camp do you fall in-heat soak and check or just test and go? Has anyone else had a wire pass dry then fail after sitting in the sun?

2 comments

2 Comments

mark_thomas12d ago

Yeah, that Frank sounds like he knows what he's talking about... I had a wire bundle on a King Air pass a cold check and then fail after an hour in the Texas sun. Heat soak is the only way to find those hidden gremlins.

the_ryan11d ago

Honestly, that "pass a cold check" part is what gets me - thermal cycling can crack solder joints that look perfect at room temp.