On June 22, 1992, a Cessna 421B (registration N39PW) operated by Shoeware Limited was involved in an aviation accident near Columbus, OH. Investigators recorded the probable cause as: THE ELECTRICAL FIRE WHICH STARTED IN A COMPONENT THAT WAS PART OF A DOOR SEAL MODIFICATION. ALSO CAUSAL TO THE ACCIDENT WAS THE INSTALLATION OF THIS UNAPPROVED AIRPLANE MODIFICATION. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An electrical fire originating from an unapproved cabin door seal system forced an emergency landing, destroying the cabin interior. Investigation revealed non-Cessna parts and missing FAA documentation.
Incident Overview
During cruise flight, an electrical fire developed in the cabin, prompting the pilot to execute an emergency landing. The fire subsequently destroyed the cabin interior.
Unapproved Door Seal Installation
The airplane was equipped with a cabin door seal that had not been approved. Investigation determined that the fire originated from a component of this door seal installation, which comprised an electric motor, an air pump, and a microswitch.
Non-Standard Parts and Documentation
All parts involved in the door seal system were identified as non-Cessna components. The Cessna 421 manuals contained no reference to pressurized door seals. Additionally, no record of an FAA Form 337 for the installation was found.