JFZ ... an excellent post IMHO.
May I also add the following view - AAR for the Hercules, and I believe for the Nimrod, was bought in at an exceedingly rapid rate in response to the requirements of the Falklands War. It worked. It worked so well it was continued AFTER the war.
Is it not possible, even probable, that many of these Safety Case/Design Studies etc etc, were simply not done due to the pressures of the time ??
When things were "tidied up" after the war, and became much more a "permanent fixture" .. I wonder how many times it was "assumed" that things had been checked the first time around, when in fact they had not ??
Everything I read in this thread seems to indicate that folks believe the introduction of AAR was done in a long slow and researched process - I don't believe that to be the case.