"Ageing Aircraft Audit" is a routine part of the MAA (carried over from previous regs) airworthiness system. IIRC (I've not been in that world for 7 years) the first AAA comes at 5yrs after ISD, and then every 5 years thereafter. They are intended to see if thgere's a forest hidden by the trees which the front-line staff are maintaining.
PDR