Exactly the point Sanus. You have answered the question yourself.
This failure of the defective part is known and at the moment has an apparent return period of 6 months in the UK fleet. Apparently the HUMS has only a relatively small chance of preventive detection, so the frequency of further undetected failures is pretty significant if the affected aircraft continue to fly.
Its only a satisfactory resolution, if you are happy with a reasonable prospect of North Sea "controlled" ditching, in the winter months.
We have been very lucky so far, that the outcomes have not involved injury or worse. What is the conditional probability of benign conditions in a North Sea winter? It gives the expression "wing and a prayer" new resonance.
B73 - thanks for pointing me at the second link. However, is it not less to do with the aircraft type/variant but more with the gearbox shaft batch part number/method of manufacture?
Last edited by Helinut; 26th Oct 2012 at 09:54.
Reason: To add acknowledgement of B73's last post