14 CFR Part 39 · Airworthiness Directives
14 CFR 39.15: ADs on a modified aircraft or part
Yes, an AD still applies after the product has been changed. Modifying, altering or repairing the affected area does not take an aircraft or part out of an AD that names it.
Section last amended December 30, 2016 · Text current as of October 15, 2026 · Also cited as FAR 39.15 · Read it on eCFR
14 CFR 39.15 in plain English
- An AD applies to each product it identifies, even one that has been modified, altered or repaired in the area the AD covers.
- If the change makes the AD's actions impossible, the way out is an alternative method of compliance under 39.19, not ignoring the AD.
Common questions
- My aircraft has an STC in the area the AD covers. Does the AD still apply?
- Yes, under 39.15. If the STC makes the AD's instructions unworkable, ask the FAA for an alternative method of compliance under 39.19.
Official text of 14 CFR 39.15
§ 39.15 Does an airworthiness directive apply if the product has been changed?. Verbatim from the eCFR, current as of October 15, 2026.
Yes, an airworthiness directive applies to each product identified in the airworthiness directive, even if an individual product has been changed by modifying, altering, or repairing it in the area addressed by the airworthiness directive.
Related
AerScheduler lists the ADs that name each of your aircraft, records who decided each one, and tracks the repeat inspections that follow. See how