When I was going through my school, I chatted with a former grad who was pink slipped for not landing center line on a grass runway. No way to contest that, nothing could be done. DPEs fail people for things that they shouldn't be failed for. I failed the MEI ride on the first attempt because I used 8" MP and Prop back to the detente to simulate zero thrust, as described by Beech for the BE-76. Was busted because I was not "...able to see exactly where 8" MP is because the MP gauge only goes down to 10" ". Even pulling out the manual and showing him still did not allow me to pass the first time. Second time I went up, did it his way (13" MP) and received the congratulatory hand shake. I assume he needed the reexamination fee to help pay for his luxury SUV with the leather interior.
In my opinion, 121 operators should not even care about failed CFI rides anyways. I'm not wanting to go there to flight instruct, want to go and fly something else besides a C-172. They should allow people to get the jobs, then if they can't make it through training, or pass their checkrides as suggested previously, then be let go. All I want is the chance to be able to prove myself, I can do it and be successful.
I've flown with a lot of guys who never failed a ride, that are at the regionals and else where, that I would be scared to put the neighbors dog on board an airplane they are flying.
Besides, wasn't the FO on 3407 the one who made a configuration change (raising the flaps) without the Captain's say so?