I understand what you say Terry and you are, of course, quite right but there are probably a lot more of these APU’s than there are Vulcan bombers right now.
There are two Vulcan’s near to me and neither have their APU’s in working order but according to the manual these units have to be run-up and tested every 7 days to stay within service. To keep everything in the aircraft working would need a full time, trained, ground crew of 18 and goodness knows what quantity of spares – an almost impossible task for the historical aircraft preservation groups.
Almost everything about this APU is over engineered and it seems that little consideration for weight has been given in many areas. This Rotax Actuator is one of two (one for the oil cooler radiator blind and one for the ‘run / stop’ fuel valve) and is a typical example where, for instance, the ‘mod record label’, which is just one small (non-critical) part, is fixed with 4 stainless screws which are then locked with seizing wire when a label could have been fixed with small rivets (like the identity label) or even had the legend engraved into the surface.
Both these actuators had age related faults, one with a jammed limit switch and the other with a seized motor shaft brake, but both units working again now.
Overall I do understand that this equipment is historically important and will outlive me so I am really just looking after it and keeping it in working condition for someone else who will perhaps carry out a full restoration job at some future date.
Tweakie.