[Shakes head in continuing disbelief at the chronic incapacity of Australia to sort this sh*t out]
All, there’s a difference between:
when maintenance has to be done (e.g. annually)
what maintenance has to be done (e.g. replace spark plugs), and
how maintenance has to be done (e.g. using the toys Leaddy says he has, in accordance with the data Leaddy says he has).
The repeal of AD/ENG/4 cannot, in itself, have an effect on all 3, because AD/ENG/4 does not, in its terms, purport to codify all 3.