Switched my crimp method after a pitot tube failure during preflight

For about 8 years I used the same cheap crimper on D-sub pins without a second thought. Last April I was doing a preflight on a Cessna 172 and noticed the pitot heat was intermittent. Tracing it back I found a pin that looked fine but the wire pulled right out with barely any effort. I switched to a proper ratcheting crimper like the Danielson DAK-95 and started using a pull test on every single pin. Now I won't let anyone on my crew touch a connector without checking their crimps first. Has anyone else had a bad crimp cause a weird avionics gremlin you couldn't find for days?

2 comments

2 Comments

schmidt.blake16d ago

That Danielson DAK-95 is a solid choice, I have one myself. But I mean, your old cheap crimper might not have been the whole problem. A lot of times the issue is also the quality of the pins themselves. Ive seen cheap D-subs from certain surplus suppliers that have softer metal or bad plating, and even a good ratcheting crimper cant fix junk metal. If the wire pulled out with barely any effort, it could have been a pin that was slightly oversized for the wire gauge, or just a bad batch. Idk, maybe its just me but I always buy pins from the same manufacturer as the connector housing if I can. Also, the pull test is huge. I do one on every pin now too, even after i've installed them in the block. It catches the ones where the crimp looks perfect but the barrel wasnt quite closed tight enough. Good on you for switching up your habits though.

schmidt.blake15d ago

Hold on, wait... 19 AWG wire with a pin rated for 20-24? That seems wild. I can see how the barrel would just never close down enough on that. Ive never tried mixing gauges that far off, but it makes total sense. Did you actually find out after all that messing around that the pin size was the problem? I would have been pulling my hair out.