Definition
The section of U.S. federal aviation regulations that establishes the airworthiness standards for transport category airplanes. It specifies the design, construction, performance, systems, and equipment requirements an airplane must meet to be type-certificated as a transport category aircraft. Most airliners and large business jets are certified under this part.
Plain English
It is the rulebook the FAA uses to decide whether a large airplane — like an airliner — is safe enough in design and build to be approved for service. If a jet meets every requirement in this rulebook, the FAA grants it a type certificate.
Context Anchor
Seen in jet airplane systems, maintenance, certification, and equipment discussions when the handbook explains why a transport category airplane is designed or operated a certain way.
Derivation
‘CFR’ stands for Code of Federal Regulations — the official collection of U.S. government rules. ‘Title 14’ is the volume covering aeronautics and space. ‘Part 25’ is the specific chapter inside that volume dealing with transport category airplanes. So ‘14 CFR part 25’ is simply a precise address: book 14, chapter 25.
Why Pilots Care
Aircraft certified under these standards incorporate specific redundancies, structural margins, and system requirements that directly affect how the airplane behaves in normal and emergency flight.
Intuition Check
Do not read “part 25” as a page number or a chapter in the airplane handbook. Here, “part” means a specific section of federal aviation regulations.
Example Sentence 1
The Boeing 737 is certified under 14 CFR part 25, which is why it must meet strict performance requirements after an engine failure on takeoff.
Example Sentence 2
During preflight, the crew confirmed that all modifications still complied with the original 14 CFR part 25 certification basis.