On March 15, 1997, a Piper PA-31-350 (registration N3542H) was involved in an aviation accident near Kotzebue, AK. Investigators recorded the probable cause as: Fracture of the left main landing gear door hinge, which prevented the left main landing gear from extending and locking. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An airplane landed with landing gear retracted after the pilot could not lower the left main landing gear. Postaccident inspection found a fractured landing gear door hinge, which had been replaced under an airworthiness directive but still failed.
Incident Overview
An aircraft was landed with its landing gear retracted after the pilot was unable to lower the left main landing gear. According to the investigation, the nose gear and right main landing gear extended and locked properly, but the left main gear remained stowed.
Investigation Findings
Postaccident inspection of the aircraft revealed a fractured left main landing gear door hinge. The hinge was identified as a new, improved version designed to replace an older hinge that had a history of cracking in the radius of the hinge. This replacement hinge had been mandated by an airworthiness directive, yet it also fractured in the same radius area.
Service History
A review of Service Difficulty Reports disclosed at least eight other instances of cracks occurring in the new hinge design. The recurrence of fractures in the replacement component suggests a persistent issue with the hinge's structural integrity under operational loads.
Probable cause
Fracture of the left main landing gear door hinge, which prevented the left main landing gear from extending and locking.