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Airworthiness Directive (AD)

Content & Format Guidelines

Airworthiness Directives (ADs) consist of two parts, the preamble and the rule. The preamble provides the basis and purpose of the AD. The rule portion provides regulatory requirements for correcting the unsafe condition.

The FAA Aircraft Certification Directorates write ADs using the guidance provided in the AD Manual. While the subject and affected products vary with each AD, the manual provides guidance regarding content and format necessary in all ADs. The AD Manual is revised periodically for improvements and changes in AD formats and procedures.

AD Content

Generally, ADs include:
  • A description of the unsafe condition
  • The product to which the AD applies 
  • The required corrective action or operating limitations, or both
  • The AD effective date
  • A compliance time
  • Where to go for more information
  • Information on alternative methods of compliance with the requirements of the AD

AD Number

ADs have a three-part number designator. The first part is the calendar year of issuance. The second part is the biweekly period of the year when the number is assigned. The third part is issued sequentially within each biweekly period.

Do all ADs include a corrective action?

No. Some ADs include limitations. However, each AD is intended to resolve the unsafe condition. For interim action ADs, actions that terminate the interim action are incorporated into an AD when they are determined.

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