Definition
The section of the federal aviation regulations that establishes Airworthiness Directives (ADs). It gives the FAA the legal authority to issue mandatory corrective actions for aircraft, engines, propellers, or appliances when an unsafe condition is found, and it requires owners and operators to comply with those directives before further flight or within a specified time.
Plain English
It is the rule that lets the FAA order fixes on aircraft when a safety problem is discovered, and it requires owners to carry out those fixes.
Context Anchor
Seen in FAA discussions of airworthiness directives, maintenance records, and whether an aircraft is legal and safe to fly.
Derivation
CFR stands for Code of Federal Regulations, the official collection of U.S. government rules. Title 14 covers aeronautics and space. 'Part 39' is simply the chapter within Title 14 that deals specifically with Airworthiness Directives.
Why Pilots Care
Pilots and owners must verify that their aircraft has complied with all applicable directives from this part, or the plane may not be legal to fly.
Intuition Check
Do not read “part 39” as just a page number or a general reference. In this context, it points to a specific federal aviation rule section with legal force.
Example Sentence 1
Before the annual inspection signed off, the mechanic verified compliance with every Airworthiness Directive issued under 14 CFR part 39.
Example Sentence 2
The flight school ensures all its training aircraft meet the requirements outlined in 14 CFR Part 39.