What does the amendment number of an Airworthiness Directive (AD) amend?

The amendment number of an Airworthiness Directive (AD) signifies changes or revisions to the existing AD, which is a component of the Federal Aviation Regulations, specifically Part 39. Each amendment number allows for tracking and identifying the latest updates, clarifications, or specific requirements associated with the AD, thereby ensuring compliance and safety within the aviation industry.

The ADs are issued by the Federal Aviation Administration (FAA) and require operators and maintenance personnel to comply with the directives as outlined. The amendment reflects any modifications made over time, which could include additional instructions, new safety information, or updates based on emerging data.

Type Certificate Data Sheets and Airworthiness Certificates serve different roles within aviation regulations. Type Certificate Data Sheets provide specific information about aircraft design and specifications, and Airworthiness Certificates confirm that an aircraft meets safety standards for operation but are not linked to the amendment process of ADs.