Aircraft Accident/Incident Report

Juneau, Alaska 99801
Tuesady, June 9, 1998 12:31 AKD

The certificated commercial pilot, and four passengers, departed in a single-engine airplane on a scheduled commuter flight over terrain consisting of open water and wooded islands. Thirteen minutes later during a climb, the pilot noted smoke and heat coming from beneath the mid-cabin floor, and declared an emergency, reporting a fire in the airplane. The pilot ditched the airplane in shallow water along a shoreline of a small island. The fire, which was located under the right front seat between the cabin floor and the lower airplane belly skin, was self-extinguished during the ditching. Post-accident examination disclosed a fuel line, a bundled set of electrical wires, and a Loran antenna cable, had all been routed adjacent to each other under the cabin floor, contrary to FAA recommended methodology. The Loran antenna cable had been installed 10 years prior to the accident. Two small holes, consistent with arcing, were found in the fuel line. Evidence of arcing was found on one of the electrical wires. Plastic tie wraps attached the wire/antenna bundle to plastic clamps that were each secured to fuselage formers under the floor by bolts or screws. One clamp, adjacent to the holes found in the fuel line, was missing from its attach point. A screw and a small melted portion of a plastic tie wrap were found adjacent to each other in the fuselage belly, beneath the cabin floor. An annual inspection was accomplished six months before the accident. A 100-hour inspection was completed 11 days before the accident. Each company inspection checklist includes an inspection of the internal structure of the fuselage, and an inspection of antenna cables. The FAA recommended technique for attaching clamps to structure is the use of bolts with locknuts, or self-locking nuts.

The failure of company maintenance personnel to properly install a wire bundle clamp; chafing, electrical arcing, and subsequent leaking of a fuel line, which resulted in an in-flight fire. A factor associated with the accident was company maintenance personnel's failure to discover a missing clamp during a 100 hour inspection.