Falcon
If I could just say, the point with the Cunningham case is that MoD could not produce the documentation its own regulations require to support the Master Airworthiness Reference. The SI stated this quite clearly.
In the circumstances you describe, a period of administrative lag is permitted, and there are ways of managing that depending on urgency. But on XX177, and Hawk in general, a rogue (forbidden by mandated regulations) Routine Technical Instruction was issued that had no supporting evidence whatsoever; meaning there was no valid Safety Case Report or Safety Case. The audit trail was badly compromised.
Of course, there is a matter of degree, but implementing the RTI rendered the seat unserviceable, but its paperwork was signed to say it was serviceable. The Service Inquiry's Convening Authority was full party to this root cause. (Again, the SI report). If Martin-Baker's servicing instructions had been followed, the release mechanism jam would not have occurred. The RTI bypassed these instructions. MoD claimed never to have them, but the RAF training video evidence proved otherwise. The Prosecution deemed this 'irrelevant', and advised the Judge so. It ain't M-B or the maintainers fault if MoD issues instructions to ignore that training. But the information DID exist within MoD, and not following it killed Sean Cunningham.