Certificate issued by the Federal Aviation Administration that means a particular aircraft design meets standard critera for production. A type certificate does not authorize its holder to produce that aircraft in any numbers. It only proves that the aircraft meets safety, airworthiness, and performance criteria. If mass production is then desired a production certificate must be obtained.

The typical type certification process takes anywhere from two to five years. All airplanes made by a manufacturer for sale in the U.S. must have a type certificate, from the Cessna 150 all the way up to the Boeing 747.

The type certification process is outlined in 14 CFR parts 21, 23 and 34. Part 21 defines certification procedures, part 23 defines airworthiness standards, and part 34 defines emissions and fuel venting requirements for turbine powered aircraft.

There are a few ways to change a type certificate in terms of modifications and flexibility within a design.

1. Supplemental Type Certificate (STC) - If a third party designs a modification to an aircraft (long range fuel tanks, more powerful engine, upgraded lighting, etc.) with a type certificate they can apply for a supplemental type certificate, they must show that the modification does not adversely affect the airworthiness of the original design. The STC describes methods of applying the modification and changes to aircraft performance or operation and must be kept with the aircraft maintenance logs.

2. Ammended Type Certificate - Rather than having to re-certify a design because of some relatively minor changes the FAA allows you to re-certify only the changes and then amends those changes to the original type certificate. Usually the same model number is retained and some other means of identifying the changed design is used. For example: The Piper PA-28-140, PA-28-151, and PA-28-235 all share the same type certificate, as do the Cessna 172A-S models.

3. Airworthiness Directive (AD) - If the NTSB recommends a change to an aircraft the FAA can issue an Airworthiness Directive. The aircraft's type certificate is then ammended to include the required AD. The aircraft is considered unairworthy until the AD is complied with.

A type certificate includes what is called a "Type Certificate Data Sheet (TCDS)." The type certificate data sheet includes general information about the design such as wingspan, wing area, wing loading, limiting airspeeds and required placards and markings, control surface travel, engine installations and approved engine/propeller combinations.

Type certificates are generally held by the manufacturer of a certain airplane although they can be transferred and some type certificates are purchased so that a company can produce aftermarket replacement parts for an out-of-production airframe.

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