After an AD has been published, there may be the need to update its content. Depending on the impact of the changes that will be included, an AD can be corrected, revised or superseded.
An AD is revised to incorporate changes that make the AD requirements less stringent than the previous revision. This may occur, for example, when the applicability is reduced; when the compliance time is extended; when an optional alternative method of compliance is added; when an optional terminating action is added; when clarification is provided (including correction of errors in the previous AD that made the accomplishment of that AD impossible); when non-substantive changes are incorporated (such as the change in the address where a Service Bulletin is available or a change in the name of the contact person)
A revised AD retains its AD number with the addition of the revision number, e.g., 2006-0067R1
Consequently, when in compliance with a previous revision of an AD, an aircraft is automatically in compliance with the new revision.
Anyway, if the AD requires a repetitive inspection, after the effective date of the new revision, compliance with the AD at the latest revision must be recorded.