Appreciation post: I found a crazy old FAA document about wire insulation

I was digging through some old boxes at our hangar in Phoenix, looking for a spare connector, and I found a faded FAA advisory circular from 1978. It was all about wire insulation breakdown. The thing that blew my mind was a chart showing that certain older PVC insulations could lose over 60% of their flexibility after just 15 years in a hot, dry environment like ours. I always knew old wire got stiff, but seeing that specific number really hit home. It made me think about all the classic birds we work on that are pushing 40 years old. Now I'm way more careful when I'm moving bundles in those older airframes, especially around hot zones like the firewall. I'm not just looking for chafing anymore, I'm gently bending wires to check for that tell-tale cracking. Has anyone else come across this kind of old data that changed their daily check routine?

2 comments

2 Comments

jade22113d ago

Ever find a manual so old it makes you rethink everything you touch? I had a similar moment with some old building codes about galvanized pipes, just a footnote about how they get brittle. You don't think about it until you see the numbers, then you're poking at every joint with a new kind of dread. That chart would live in my head rent free too.

susanh4613d ago

Doesn't that happen with everything once you know how it's made?