Re PTU’s etc in post #17. Certainly on the 75, the purpose of the PTU is to drive some remnants of the main (L) system in the event of a L Hyd loss of contents (Flaps, gear, nose wheel steering and, for ETOPS, a hyd gen). The trick, of course, is to know where the actual leak has occurred. If it is above the stack pipe, the PTU will operate as per the tin, but if it is below it, then “Misd-agin’s” comment about a surprise is nearer the mark. However, there is one fairly big clue as to where the leak might lie, thus obviating any surprises later on.
Prober