Airworthy Airplane
Supplemental Type Certificates (STC's)
A Supplemental Type Certificate (STC) is a document issued by the Federal Aviation Administration approving a product (aircraft, engine, or propeller) modification or alteration.
A STC is a change to the aircraft original Type Certificate (factory type cetificate).
The STC defines the product design change, states how the modification affects the existing type design, and lists serial number effectivity. It also identifies the certification basis listing specific regulatory compliance for the design change.
The STC and its related information - all drawings, data and specifications - are the property of the company holding the STC (STC holder).
To approve for return to service an aircraft modified by a STC, a FAA Form 337 must be completed. The STC is used as FAA approved data, a logbook entry is also required.
The 337 must be signed off by authorized persons : Item 6(Conformity Statement) must be signed off by the person performing the alteration(A&P or Repair Station). Item 7 (Approval for return to service) may only be signed off by an IA , a FAA Repair Station or FAA Designee.
Please click the image below to see cabin interior modifications and upgrades applicable to your aircraft:
Click the link below to see performance upgrades STC´s for Beechcraft King Air, Cessna Caravan, Cessna Conquest and Piper Cheyenne series: