Originally Posted by
tdracer
Assuming the problem was "intermittent", troubleshooting becomes very, very difficult and the Maintenance Manual/Fault Isolation Manual are not always a lot of help. Anyone who's a backyard mechanic can appreciate how frustrating it can be to find a problem that only occurs when you're driving 60 miles per hour - but not every time you drive 60 miles per hour.
I became a big hero to a particular operator many years ago when, after looking at some DFDR data, I figured out that their recurrent FADEC problem they'd be trying to solve for a month was occurring when the leading edge devices were retracted. I told them to go look at the wire bundles in the vicinity of the leading edge actuators and they found the chaffed bundle problem the next day.
I wouldn't be too quick to condemn maintenance because they struggled to correct an intermittent fault.
Thanks for your insight, but if you have a recurring (so not intermittent) issue with a critical flight control system/component would you "troubleshoot" on a revenue flight. The only clearly different variable across the 4 flight segments (that I'm aware of) is the presence of the engineer (in the cockpit?)...