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ADC 429 popped on the #2 air data computer right before departure, and the fix was a 3 inch static line
Last Tuesday I was doing a ramp check on a King Air 200 in Wichita and the left ADC decided to throw a 429 fault about 20 minutes before the crew showed up. I pulled the fault codes and it kept pointing at the air data computer, so I swapped it with a known good unit, which took me about 45 minutes with the rack and the pitot static lines. Problem is, the fault came right back on the new box, so I started tracing the static line from the left pitot static adapter. Turns out a 3 inch section of the static line behind the panel had a crack you could not see with your eyes, but it showed up right away when I put 5 psi on it and hit the line with soapy water. Replaced the line, did a leak check on the whole system, and the ADC came back clean with no faults. Has anyone else had a cracked static line fake out an ADC like that, or am I the only one who skips the line check when the box looks bad?
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the_river22d ago
The part about the cracked line behind the panel being invisible to the eye really hits home. I used to just swap the box when a 429 popped and call it a day, mostly because pulling panels to check lines felt like a waste of time. After getting burned twice on that, I do the soapy water test first now, it's saved me way more hours than it's cost me.
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