Harry
Excellent post.
On the other hand IF an aircraft has been operated for many years without mishap there is clearly a body of evidence (or a statistical number) that it is not as unsafe as (say) the F-104G or an Indian Mig-21.
As dragartist says, the aircraft have been stripped and rebuilt by L-3. The problem you have to contend with is how to reconcile the differences between the new standard (rebuilt to different standards) and what has "operated for many years without mishap".
If the differences are minor, then the MAA may choose to give more weight to this historical evidence.
However, if the cumulative differences are great, there is no supporting evidence to plug gaps in knowledge and the Aircraft DA is reluctant to sign up to changes, then the MAA may play the red card. The evidence suggests something like this has occurred.
It boils down to "engineering judgement". As MoD admits it lacks this expertise, Philip Hammond will presumably bring his to bear.
