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Found out a weird fact about aircraft wiring from the 80s
I was reading an old maintenance manual from 1985 for a Gulfstream I worked on last week. Turns out they used a Teflon coated wire that looks exactly like the modern stuff but it had a DIFFERENT insulation rating that could crack at 150 degrees instead of 200. Nearly swapped in the wrong replacement on a pitot tube harness because I assumed it was the same. Has anyone else run into this weird spec change on older airframes?
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the_emery4mo ago
Manuel from my shop actually flagged this exact thing on a Citation II last month, and I told him he was being paranoid. Had to eat crow when I pulled the old wire specs from a 1983 supplement and sure enough the jacket was rated at 150 degrees like you said. The kicker is the teflon coating feels identical to the modern stuff, so unless you're checking the part number die stamp every time you're basically gambling. I've personally swapped out three pitot heat elements thinking the wiring was fine only to find hairline cracks after a cold soak. Makes me wonder how many field repairs from the 80s are still flying around with that underspecced wire. Still, beats the old lacquer coated stuff from the 70s that would just turn to dust if you looked at it wrong.
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young.kim4mo ago
Finding the exact spec sheet for the old part saved me from a similar mistake on a King Air.
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