WAH
Ref your post #64 I think you are on a different HUMS planet from us lot on the N Sea. There is no way that the tech log would have a deferred defect entry saying "dodgy HUMS M6* reading on gearwheel x, keeping an eye on it...". It might say that an element of the HUMS system itself was U/S, with a total of 25 flight hrs being allowed until the problem is fixed.
So your comments about pilots needing to be concerned about looking at HUMS trends is totally wide of the mark.
Regarding the Norne accident, I believe that HUMS was not mandatory in Norway at that time, and perhaps it was not taken as seriously as it should have been?
Its worth bearing in mind that engineering actions in the event of an adverse HUMS trend depends on the equipment manufacturer. For example, since the IHUMS system was invented by Bristow, when there is a HUMS issue on our 332L, S76A etc, we (our HUMS type engineer) will decide what to do about it. However if its EuroARMS or M'ARMS on an L2 or 225, as soon as an amber or red traffic light is produced by the groundstation, its straight on the phone to Eurocopter and they decide what to do about it.
But at no point in that loop is the pilot involved, nor should he be since he generally doesn't understand the issues and is in no position to decide whether the aircraft is serviceable or not.
Can I also point out that whilst you said
If HUMS was within the thresholds, then there's obviously nothing wrong
that presupposes that the thresholds were correctly set. A very brave assumption since the thresholds are generally set by guesswork, modified only in the light of excessive false alarms or failure to detect a failure. Its for this reason that the GE work is so important.
HC