On November 27, 1999, a DE Havilland DHC-7 (registration N273EP) operated by Raytheon Systems Engr'g was involved in an aviation accident near Kwajalein, MS. Investigators recorded the probable cause as: The failure of the flight crew to properly execute the emergency landing gear extension procedure in response to a landing gear unsafe cockpit indication. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
After a nose gear unsafe indication, the flight crew believed it was a false alarm based on visual inspection. During landing, the nose gear collapsed. Investigation revealed a failed actuator and that crew did not follow emergency extension procedures.
Incident Overview
While approaching the destination airport, the flight crew lowered the landing gear and received an unsafe indication for the nose gear. Without landing, the flight returned to the point of departure. The pilot-in-command then inspected the nose gear alignment marks through the inspection window and concluded that the nose gear was down and locked, attributing the unsafe light to an erroneous indication.
Landing and Gear Collapse
During the landing rollout, the nose landing gear slowly collapsed as the weight of the aircraft transferred to the nose. The aircraft was recovered from the runway, and subsequent operation of the emergency gear extension hand pump successfully lowered and locked the nose gear in eight strokes.
Investigation Findings
The operator's investigation identified a failure at the boss end of the nose gear extend actuator. Additionally, it was determined that the flight crew did not perform the emergency gear extension procedure as specified in the Airplane Flight Manual (AFM).