Casualties unknown

2000-12-14: Cessna 421B (N781SL) — Lifeguard Air Ambulance, Inc. — Pensacola, FL

Pensacola, FL, US

On December 14, 2000, a Cessna 421B (registration N781SL) operated by Lifeguard Air Ambulance, Inc. was involved in an aviation accident near Pensacola, FL. Investigators recorded the probable cause as: Failure of the washer retaining the bolt in the left main gear scissors, resulting in separation of the scissors and inability of the landing gear to retract. 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

After takeoff, the landing gear would not retract and the warning horn sounded. Unable to land at the destination due to weather, the pilot returned to the departure airport. During landing, the aircraft swerved left and the left main gear collapsed and separated. Investigation found a failed washer in the gear scissors.

Accident Sequence

Upon departure, the pilot initiated a landing gear retraction, but the gear did not retract and the landing gear warning horn activated. Deciding to continue, the pilot flew to the original destination. When weather at that airport prevented a landing, he turned back to the departure airport. On landing rollout, the aircraft veered to the left accompanied by a squealing sound from the left main landing gear tire. Subsequently, the aircraft exited the runway surface laterally and the left main gear assembly collapsed and detached from the aircraft.

Investigation Findings

After the accident, an examination of the aircraft was conducted. It was determined that the washer that retains the bolt in the left main gear scissors had failed. Consequently, the scissors separated, allowing the left main gear to rotate. This rotation prevented the ground switch located on the scissors from opening during takeoff, which in turn inhibited the landing gear retraction mechanism.

Relevant Service Information

The failed washer was specifically referenced in Cessna Aircraft Company Service Information Letter ME83-37, issued November 23, 1983. That letter recommended replacing the original washer with a thicker unit at the next scheduled 100-hour inspection.

Probable cause

Failure of the washer retaining the bolt in the left main gear scissors, resulting in separation of the scissors and inability of the landing gear to retract.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001226X45490. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.