Cessna 337 Super Skymaster — Other Documents

This document, produced by the FAA Safety Promotion Program Office, addresses the risks associated with layering Supplemental Type Certificates (STCs) on aircraft, specifically highlighting incidents involving the Cessna 337. It emphasizes the importance of ensuring that any modifications made to the aircraft are compatible with existing alterations to maintain airworthiness. The document serves as a resource for aircraft owners, operators, and maintenance personnel to understand the implications of STC modifications and the necessary precautions to take. It includes safety recommendations from the NTSB and guidance on documenting weight and balance changes in aircraft records.

• Cessna 337 incidents highlight the risks of layering STCs.
• Weight and balance changes must be documented in the aircraft record.
• Modifications must be compatible with previous alterations to maintain airworthiness.
• NTSB recommends educating, evaluating, and documenting modifications.
• FAA guidance stresses the importance of installer responsibilities regarding STC compatibility.