An airworthiness directive commonly known as an AD is a mandatory instruction that must be carried out when it is applicable to your aircraft within a given time frame.
The airworthiness directive for example might be repetitive in nature, it might have an option to terminate the requirement by performing a modification or it might be a one-off task. One query you might have to address is the embodiment or accomplishment date for a given AD and this can be very important, especially when considering any instructions for continued airworthiness
(ICA).
So what is the correct reference date for accomplishment of an AD required actions; well we can
make it a little easier and ask what the accomplishment date for a maintenance task is. For any maintenance task – including AD required actions – the date of release is the date when the Certificate of Release to Service (CRS) is signed by duly authorised certifying staff.
It is only certifying staff who are competent to make the final airworthiness determination and therefore the CRS reference date does not necessarily coincide with the date when the individual maintenance task was actually performed and signed off by maintenance staff.
This question comes up regularly on Technical Record Reviews and a colleague of ours answered it perfectly today by means of a data-driven answer and not an opinion, the answer can be found as FAQ no. 19496 on the EASA website.
You can see here that there is a vital difference in the dates, and this is very important to be aware of during a review.
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