Originally Posted by
PDR1
Somewhere way upthread it was explained why a civil airliner designed in the 40s/50s had much greater structural margins than one from more modern eras. And of course the Nimrod wasn't just a comet with a bomb bay - there were significant structural differences - especially in the wing root and C/S area (aside from anything else it needed to be different to fit the Nimrod's Speys rather than the Comet's Avons (the spey having 25% greater diameter and 35% more length).
PDR
Just as a P8 isn't just a 737 with a bomb bay. Besides - with modern fatigue monitoring and prediction the ability for airworthiness regulators / Air Force to measure the fatigue cycles is far in advance of the 1950's "over engineering"