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ARINC 429 wiring was my blind spot until I saw a 731 install
I spent 9 years doing general avionics work, mostly on older GA planes where we could get away with twisted pairs and basic soldering. Last month I helped a buddy on a Gulfstream GIV-SP that had a brand new 731 conversion, and the ARINC 429 bus wiring was night and day compared to what I've done. He showed me how they terminated every stub with a specific resistor value and used proper bus coupling instead of just splicing in like I usually do. Within a week I went back and rewired a King Air data bus that had intermittent dropouts, and it's been rock solid for 3 straight flights. The difference was really about paying attention to terminator placement and line length, not just signal voltage like I assumed. Has anyone else had a similar wakeup call on bus architecture from seeing a proper retrofit side by side? What did it take to make it click for you?
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umar591mo ago
I feel you on this one. I did line work for years on smaller stuff and thought I had a handle on data buses until I watched a guy do a proper 429 install on a Citation. He spent almost an hour just on drain wires and shield grounding, and I remember thinking it was overkill right up until we ran the checks and every reading was clean. The terminator placement thing got me too, because I always figured if the voltage looked good on the meter then it was good enough, and that is just not how it works. It is humbling to realize how much of what I called good enough was really just luck on shorter runs. Glad your King Air fix held up, that must have felt great after chasing dropouts.
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