Spent 6 hours chasing a phantom fault on a King Air, wiring or box?

Last month I had a King Air 200 come in with an intermittent heading flag on the pilot side, and I figured it would be a quick connector reseat. It took me 6 hours across 2 days to trace it, and the whole time I was second guessing whether to blame the flux gate or the HSIs. Side A says always suspect the wiring first since corrosion and chafing are common, and it is cheaper to inspect than to pull a box. Side B says the boxes are getting old enough now that internal faults are just as likely, so you are wasting time if you do not swap first. I ended up finding a worn pin in a cannon plug behind the panel, but I am still not sure I would go wiring first on the next one. Where do you all start on intermittent stuff, wiring or the black boxes?

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tessa_adams314d ago

Used to swap the box first every single time until a Baron taught me a lesson last year. Swapped a brand new HSI on day one, flag came right back two flights later, turned out to be a chafed bundle near the gear well that only rubbed when the gear cycled. Cost the owner a core charge for nothing and me a day of looking dumb. Now I split the work: wiggle test and pin drag check on the plugs first, since that takes 20 minutes and catches most of my gremlins. If the pins and wire look clean and it still acts up, then I go for the box. Your worn pin story is exactly why I flipped my whole way of doing it.

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