That wiring diagram in the 737 AMM surprised me this morning

I was digging through the Boeing 737 maintenance manual this morning to trace a faulty position light circuit, and I stumbled across a fact I'd never noticed before. The manual actually specifies the exact voltage drop tolerance for each connector pin in the wing tip assembly. I always figured you just check for continuity and move on, but no, there's a specific 0.2 volt max drop per pin listed in section 33-41-00. I've been doing this for about 7 years now and never once cracked that part of the book. Makes me wonder how many other little details I've been glossing over that could have saved me troubleshooting time. Has anyone else found a weird spec buried in the AMM that you'd never heard mentioned by any lead mechanic?

2 comments

2 Comments

danielhenderson20d ago

0.2 volt max drop per pin" yeah I remember hearing about that from an old timer at a mx shop I used to work at. He always said Boeing buried the real gold in the notes sections because most guys just skim the big diagrams. I think it was in a thread on a aviation forum where some guy found the tolerance for wire twist per inch in the galley power harness, something like 3 to 5 twists per foot. Never saw that in any training class either.

terry_lewis2120d ago

Wait, wouldn't you actually want them to catch those buried details so the job gets done right the first time instead of having to tear it all apart later? If the notes are that important, maybe the issue is more that training should cover them better rather than hoping guys stumble on them by accident.