Casualties unknown

2007-05-30: Cessna 340A (N17MH) — Middleton, WI

Middleton, WI, US

On May 30, 2007, a Cessna 340A (registration N17MH) was involved in an aviation accident near Middleton, WI. Investigators recorded the probable cause as: Failure of the right main landing gear extension and retraction linkage, which allowed the gear assembly to collapse during landing rollout. An additional cause was the improper adjustment procedure(s) by undetermined mechanic(s). 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

Pilot reported three green lights and a light touchdown before shudder, gear horn, and right main gear collapse. Post-accident examination found bellcrank flange failures, consistent with cumulative improper downlock adjustment.

Accident Sequence

During a dual proficiency flight, multiple approaches and landings were conducted. Prior to the accident landing, the pilot observed three green lights indicating the landing gear was properly extended. The touchdown was described as “light.” A few seconds after touchdown, the aircraft began to shudder, and the landing gear warning horn activated. The airplane started to drift to the right, and the right wing began to settle. As the right main landing gear collapsed, the aircraft departed the runway pavement, striking two runway lights. It came to rest in a grass area adjacent to the runway. The nose and left main landing gear remained extended throughout the event.

Post-Accident Examination

A post-accident examination of the aircraft revealed that the forward bellcrank attachment flange on the landing gear strut had failed. Additionally, the lower flange on the bellcrank also failed. According to the airplane manufacturer, the location of these failures was consistent with the cumulative effect of improper adjustment of the downlock mechanism over time.

Maintenance Findings

No improper adjustment procedure could be attributed to any specific maintenance action or to a particular mechanic. Furthermore, the maintenance log entry related to adjustments made during the most recent annual inspection indicated that the airplane maintenance manual instructions regarding landing gear adjustments were complied with properly.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20070703X00857. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.