Many roads will lead to the AES IPT. It would be up to them to fend off criticism and deflect blame.
But for starters, if you want to chase documentary failures, the RTI is a place to start.
A UTI/RTI/STI will have a standard format and will incriminate the author.
We already know (I think) that it said "refit shackle" or similar, and that will be derived from the author referring to the seat AP. If neither say "replace" stiff nut with new item - you have a starting point.
Later in the document it will have a few formatted details
Manhours :- XXXX
Spares Required:- ....if it says "NIL" then this compounds the first mistake.
In fact, it more than compounds the first mistake. It means that the author can't blame the tradesman for not following best practise.
(Chug, our posts crossed)