I will second that! As a former Unit Maintenance Test Pilot, post-maintenance flights were always the best briefed, best researched, and the ones that had the most thorough preflights, from a special purpose designed checklist. Whilst they had the greatest chance of things going wrong (the only time I ever experienced a compressor stall for example) they were also the flight where you had planned for things to go wrong and had planned and briefed your "What if's". The 8P's was the key to doing it properly! But there was still a good chance for things to go wrong if you let good old fashioned complacency sneak in! I recall one flight (was in fact on my UMTP course) we attended a 3rd party maintenance facility where deeper level maintenance was done. In this case an R4 (the most comprehensive almost a full strip and rebuild of the entire aircraft). My self and the instructor drove down to pick up the aircraft and sign the acceptance paperwork we briefed the hell out of the sortie in the car on the way. We walked out to do the acceptance test flight with checklists in hand, we climbed up to start the preflight from the roof of the aircraft (in this case a UH-1H), we looked at the rotor head (had seen them thousands of times before) and I said to the instructor "I Can't put my finger on it but it just doesn't look right". He said "Well let's make sure we get the checklists out and do a good job of it" was the reply. About the 3rd item on the checklist referred to inspecting a certain piece of lock wire. It wasn't there "BIG red flag", neither was the next one, then it dawned on us that MOST of the pieces that had to be Lockwired had not been... Now the maintainers amongst you will say "that can't happen it must have been checked by at least 5 people before it got to you". Yes, it had been checked and signed off by more than 3 people. BUT WORSE it had flown 3 times by the company test pilot like that (accep[tance and vibe test runs) before they deemed it serviceable to hand to us for acceptance back to the unit. We called the company test pilot to come over and have a look at something we wanted to show him... The look on his face was rather white and concerned when he realized he had flown that aircraft without most of the important bits lockwired on!! Lets say it failed the acceptance flight, there was 2 mountains of paperwork, and it was a LONG time before it was presented as ready again while they checked everything that had been signed off!! So yes maintenance test flying can be risky, but you have to plan and prep and brief... and then something unexpected is bound to happen!