14 CFR Part 25 (Transport Category Airplanes)

The FAA airworthiness standard containing the detailed type design requirements for transport category airplanes — typically jet-powered commercial aircraft with more than 19 passenger seats or a maximum certificated takeoff weight above 19,000 pounds. Part 25 prescribes structural, performance, flight characteristics, design and construction, powerplant, equipment, and electrical systems requirements. It is one of the most comprehensive airworthiness codes in the world.

The EASA Certification Specifications for large aeroplanes (transport category), the European equivalent of FAA 14 CFR Part 25. CS-25 prescribes detailed airworthiness requirements for the design, construction, and performance of large aeroplanes used in commercial air transport. It is extensively harmonized with Part 25, though differences exist in specific requirements, particularly in areas such as ditching, lightning protection, and cabin safety.

A formal approval issued by the certifying authority that confirms a product's type design complies with the applicable airworthiness requirements. A TC is issued for aircraft, aircraft engines, and propellers upon successful completion of the type certification process, which involves demonstrating compliance with every applicable regulation in the certification basis through analysis, test, and inspection. The TC defines the approved type design, operating limitations, applicable regulations, and conditions and limitations.

The complete set of airworthiness requirements (regulations at specific amendment levels), special conditions, exemptions, and equivalent safety findings that an applicant must comply with to obtain a design approval. The certification basis is established by the certifying authority early in the certification project and is documented formally. For a new TC, the certification basis is determined by the applicable regulations in effect on the date of the TC application, plus any later amendments elected by the applicant or required by the authority.

Additional airworthiness requirements prescribed by the certifying authority when the existing regulations do not contain adequate or appropriate safety standards for a particular design feature, technology, or operational use that is novel or unusual. Special conditions have the same legal force as the regulations themselves and become part of the certification basis for the specific project. They are used when the existing code was not written to address the specific design characteristic or technology being proposed.

A formal determination by the certifying authority that an alternative means of compliance, while not literally meeting the text of a specific airworthiness requirement, provides a level of safety equivalent to that intended by the requirement. An ELOS finding allows the applicant to use compensating factors, design features, or operational limitations that achieve the same safety objective through different means. ELOS findings become part of the certification basis for the specific project.

The condition of an aircraft, engine, propeller, or part whereby it conforms to its approved type design and is in a condition for safe operation. Airworthiness is a composite concept that encompasses both initial airworthiness (the design meets the applicable airworthiness standards at the time of certification) and continuing airworthiness (the aircraft remains in conformity with the approved design and in a safe operating condition throughout its service life). An aircraft is legally 'airworthy' only when both conditions are met.

The complete technical definition of a product, including all drawings, specifications, and data that define the configuration and design features of the product, its components, and the information necessary to define the airworthiness, noise, fuel venting, and exhaust emission characteristics of the product. The type design is the 'master definition' against which all produced articles must conform. It includes the drawings and specifications necessary to define the structural strength, performance, operating limitations, and all other design attributes of the product.