Rigga
Engines is absolutely correct. My recollection was that the regualtions were not specific about when (peacetime/operations) but were limited in application (numbers of aircraft) and for limited duration (for the duration of the trial) but have no way to prove it. SEMs could be just as easily applied as STFs, the evidential requirement was very loose.
DV
It was a systemic failure across the board, operators and engineers, driven by the pressures to not say no. Heads rolled if individuals spoke out, or they were worked around.
Engines
RAF instructions never got near 2 star but we were not as top heavy as the RN
