Originally Posted by
MurphyWasRight
Could someone who knows the regulation and actual practice comment on the allowed role of a flying spanner?
Seems sensible to me that on a revenue flight they should have no input unless an emergency is recognized in which case one of course one would use whatever resources seems appropriate.
Attempting to debug a possible intermittent problem while carrying passengers should be way outside the permitted realm.
I've done both "flying spanner" - which is paxing on the flight so as to have engineering coverage at an outstation, and being an observer for intermittant faults which is really not helpful in most cases anyway.
Flying spanner I have usually sat in the cabin, although on short flights on one contract sat in the jumpseat as the passengers on that contract asked me too many stupid questions when I was in the cabin.
I have done observation flights for things like yaw dampers dropping out on takeoff rolls and the like, but you can't tell much other than "yes the yaw damper dropped out" CDS fault summaries and QAR provide much more data from which you can analyse faults, if you have technical support (thats what the likes of Boeing are for).
I have been asked advice on what to do with failures when in the jumpseat, and my advice is always "whatever the QRH says" then after that is actioned I have discussed the system with crew. But not for troubleshooting, more for crew information.