Originally Posted by
Vendee
In my days, engines were pulled initially due to mechanical failure i.e. M08 blades failing and combustion chamber unzipping. Other than that, they were pulled when the thrust was below the minimums during the pyro clean/cal.
A lot of people hated working in the engine bay because of the repetitive nature but I enjoyed the challenge of getting my engine pass off with the required thrust. It was easy if you were supplied brand new modules to build your engine but that never happened. If you were given a HP comp with 300 hours on it, you knew it would be a struggle because although it was life'd at 1200 hours, after 300hrs, the internal seals were worn and it was losing thrust. The trick was to try and manage the other rotating seal clearances throughout the engine. When the manual gave a min and max clearance, you had to aim for the minimum to give you a chance. I don't recall us having any problems with badly built engines. (edit... just remembered one which self destructed on the test bed)
When I last popped into Marham engine bay in 2009, they were operating a pulse line system where the teams didn't get to build the entire engine, just part of it. It must have been soul destroying and I know that morale was at rock bottom.
Vendee my friend.
Firstly please don't think that I or anyone else for that matter were accusing the RAF Engine Bays of building bad engines. That is certainly not the case.
Moreover, optimising the seal clearances especially S14 at the rear of the HPC was the most important thing to do.
When the single crystal HPT and IPT blades were introduced, the prime cause of engine removal widened out with no single dominant cause.
I had retired before the transfer from Marham to Bristol but I kept in contact with the guys working on RB199 and they were very proud of the reduction in test bed rejects as well as the reduction in the engine removal rate.
I am aware of some of the reasons but it would not be right for me to post them on an open forum.
Anyway as I said; it will soon pass into history which I am sure for your (because I can tell you were passionate about it) and for me is a real shame.
NB. I would be happy to communicate with you but not via pprune.