Casualties unknown

2004-07-02: Cessna 421B (N421KS) — Portland, ME

Portland, ME, US

On July 2, 2004, a Cessna 421B (registration N421KS) was involved in an aviation accident near Portland, ME. Investigators recorded the probable cause as: Failure of the right main landing gear down-lock mechanism resulting in the collapse of the right main landing gear. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

Aircraft landed and veered right due to broken right main landing gear down-lock components. Metallurgical examination showed overstress separation with no fatigue.

Event Description

After being parked on the ramp, ground personnel reported to the pilot that heavy wind and rain had moved the airplane laterally across the ramp about 25 feet. The pilot subsequently departed. During the landing gear retraction cycle after takeoff, an unfamiliar "clunking" noise was heard.

On approach to the destination airport, the pilot extended the landing gear and observed all three landing gear down and locked indicator lights illuminated green. During the landing rollout, the pilot heard the "clunk" noise again. The right wing then began to settle lower than normal, and the airplane veered to the right, coming to rest in the grass on the right side of the runway.

Investigation Findings

Examination of the right main landing gear revealed that two components of the down-lock mechanism had broken. These parts were sent to the National Transportation Safety Board Materials Laboratory for metallurgical analysis. The examination of the mating fracture surfaces showed features typical of overstress separation. No evidence of fatigue was found on the fractures.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20040726X01065. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.