Hi, boeingbus; sorry for not replying earlier, I've been away. rwm's got it in one - wherever there's a need for something to back up a part, some individual will find a way to 'create history'
That's why on all certification (JAA Form 1, FAA 8130-3, even a Certificate of Compliance) there should be a declaration to the effect that the paperwork does not count as authority to install...sounds funny, but what it means is that it's up to the certifying engineer to ensure that the subject part is fit for use.
Now, of course that's where it gets tricky...you can measure a bolt or washer, so it's dimensionally correct. But what material is it made from? Steel, Ok, we can all tell that. But what strength steel? Now take an IDG or starter motor and how can you ever tell what's been done to it?
Years ago, parts were accepted purely on the basis of the paperwork. Then, a tragic accident involving a Norwegian Convair led the authorities into the maze of unauthorised parts. A combination of phoney APU bolts and duff elevator attachments caused the loss of the aircraft and all occupants.
So, pressure was put upon vendors to declare the history of their parts. Fine, except that the certification was written by the vendors, and nobody checked the history anyway. When I left the spares business five years ago, buyers had begun to request proof of purchase from the vendors - that is to say that the seller would need to show who had sold the parts to him, and if it was another vendor, the proof from that vendor, all the way back to an airline, manufacturer or reapir station. Still not impossible to forge the paperwork, tho'.
At the end of the day it's down to the Airline's Quality and Purchasing Departments to use only vendors with a solid reputation, which means (in the case of smaller vendors) a long haul in building up that reputation.
Good luck to your friend, he can do it if he is honest and has good contacts.