Try this:
http://www.wnxx.com/files/Codes.rtf
The F exam consists of component stripping and complete refurbishment of the locomotive whilst the engine crankcase, alternator and crankshaft remain in situ. This work has been carried by several teams of highly skilled technicians utilising new and reconditioned components that have been supplied to the highest standards of engineering quality. Typically, bogies, cylinder heads, pistons, liners, connecting rods, radiators, compressors, traction motors, turbo chargers and intercoolers are some of the componenets that are removed. Once reassembled, the locomotive is subjected to a lengthy and rigorous testing programme utilising Load Banks which verify that it is performing to the prescribed performance levels and producing a nominal 1750hp before being returned back into traffic.