The PFCU system was a very reliable system, after a few initial problems, and in the 10 years I was with the VC
-10 I do not recall them being a problem. The biggest problem was if something went wrong with the elevator PFCU as they were so high from the ground, and I always remember the feeling of relief after working on one, using a cherry picker, on the ramp at LHR
. It was good to get down in one piece, Prior to the introduction of the VC
-10 BOAC had to build a special overhaul workshop for them where the air was finely filtered as the limits on the PFCU components was very tight.