Originally Posted by Airprox

Going way way back since the days when BA were a reputable company who liked to do things properly and not always just pay the absolute cheapest for everything, they have always been keen on doing maintenance right. Strangely, engines is one of the things they still stick with the same principles today, BA will only allow brand new parts or parts that have been only in BA engines previously to be used in their engines. Rolls Royce in Derby and GE in South Wales both had a completely separate warehouse setup of BA only parts in addition to their normal supply of certified parts from other users that get swapped around. I know this is certainly still the case at GE and I presume is still the arrangement with RR.