Engines
Correct in every respect.
You mention DGA(N). It was no surprise that it was a retired DGA(N) (Admiral Ron Holley RIP) who was initially most vocal about the fundamental airworthiness failures on Chinook Mk2. He was one of those people whom you could rely on 100% - if he said it wasn't airworthy, it wasn't.
The very last time I saw him he was standing on a table at an RPC in DGA(N) HQ telling his junior officers (up to senior Captain!) exactly what you've just said about engineers. Later, he was appalled at the new concept that emerged in MoD (not just RAF); that non-engineers were permitted to self-delegate technical and airworthiness approval, and over-rule safety/design decisions in the interest of achieving Time and Cost targets.
But what the system does not legislate for is senior officers, of whatever persuasion and specialism, lying through their back teeth to further their own careers, and protect their predecessors. A madness overcomes some of them when they acquire power. Do we not have a form of assessment that can divert their career paths to somewhere like Broadmoor?
I just don't think the MAA has the bottle to go there. For all they are doing, I do not think they can prevent another Bagnall, Alcock and Graydon, whereby CA's Switch On Only clearance was magically converted into a full operational RTS; and when challenged, their successors in D/Air Staffs denied the very existence of an RTS (in 1993, so according to them you can't possibly have prepared one for FA2!!).
Min(AF) issued a grovelling apology to the family (the first I've ever seen), but no action was taken against the perpetrators. The beautiful irony is that in their attempt to protect their VSO predecessors and blame the pilots, they actually shot themselves in the foot, because Lord Philip was utterly disgusted at the lie (and the attempt to blame Sir Donald Spiers). Now, what the MAA needs to do is acknowledge all this; only then can it move forward in the right direction.