Unpopular opinion: I hit 500 flight hours on a single LRU and it changed how I see reliability

Just finished the logs on a comms transceiver from a regional jet, and the thing had logged 512 hours without a single fault. Not a hiccup. I was shocked because the manual for that unit lists a mean time between failures of 350 hours. We're so trained to expect things to fail on schedule, to swap them out preemptively, that seeing one just quietly do its job for that long felt weird. It made me question all the scheduled removals we do. Are we tossing perfectly good parts because a book says so? This specific box, a Collins Pro Line 21 unit, just kept going. Has anyone else had a piece of gear blow past its supposed life limit and make you rethink the whole 'if it ain't broke, don't fix it' rule in this trade?

2 comments

2 Comments

spencer_wood1mo agoTop Commenter

Honestly, saw that with an old air data computer on a King Air. Thing ran almost double its book life before it finally gave a weird pressure reading. Tbh it made me a lot less quick to pull stuff just because the hours are up. Sometimes you get a good one that just lasts. Now I check the fault history way closer before I write up a swap.

riverwhite1mo ago

Man, I gotta hard disagree. That one box beating the odds is cool, but it's pure luck. For every story like yours or spencer_wood's, there are ten units that fail right on schedule or even early. The book numbers come from testing thousands of parts, not one lucky one. Swapping on schedule is what keeps the bad one from failing at the worst possible time. I'd never want to be the guy who pushed a part too far because of a good feeling.