On June 4, 1983, a Cessna T337H (registration N1497S) was involved in an aviation accident near Redding, CA. Investigators recorded the probable cause as: The failure of the landing gear to lock during extension was attributed to contamination of the hydraulic system, specifically metal shavings found in the fluid lines connected to the hydraulic power pack. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
Aircraft returned to departure airport after landing gear failed to lock during approach. After circling for two and a half hours as darkness approached, the plane landed with partially extended gear. Inspection revealed metal shavings in hydraulic lines.
What happened
During the final phase of landing at a private airstrip, the pilot attempted to lower the aircraft's landing gear but discovered that the mechanism would not lock into place. The crew immediately initiated a return to the departure airport. Upon arrival, the aircraft circled for two and one half hours while darkness began to set in. Eventually, the pilot executed a successful landing with the landing gear partially extended.
The investigation
Following the incident, investigators examined the hydraulic system to determine the cause of the malfunction. The inspection revealed the presence of metal shavings and filings within the hydraulic fluid lines that connect to the hydraulic power pack.
Probable cause
The failure of the landing gear to lock during extension was attributed to contamination of the hydraulic system, specifically metal shavings found in the fluid lines connected to the hydraulic power pack.