On April 30, 1996, a Boeing 737-300-3H4 (registration N331SW) was involved in an aviation accident near Ontario, CA. Investigators recorded the probable cause as: The over extension of the strut was a result of the gradual breakup of the bearings and bearing carriers due to improper/incompatible wear surfaces from the repair facility's improper assembly at overhaul. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 2 related events involving the same aircraft type or operator are linked below.
A pilot experienced unresolved left main landing gear issues, performed emergency procedures and low-G maneuvers, then diverted to another airport for an emergency landing with minor damage and no injuries.
Incident Overview
A pilot reported an unresolved main landing gear problem while operating an aircraft. The pilot orbited the area and performed normal emergency gear extension procedures, which were unsuccessful. Subsequent attempts included low-G maneuvers and touch-and-go landings intended to lower the left main landing gear. The pilot eventually diverted to an alternate airport where an emergency landing was conducted. The landing resulted in minor damage to the aircraft, and no injuries were reported.
Post-Incident Examination
After the incident, the landing gear was removed and disassembled for inspection. Examination revealed that the upper bearing carriers and bearing half shells were out of position in the upper portion of the oleo strut. The over extension of the strut occurred as a result of the gradual breakup of the bearings and bearing carriers. This breakup was attributed to improper and incompatible wear surfaces, which stemmed from the repair facility's improper assembly during overhaul. Additionally, compression/extension measurements after installation were not required.
Probable cause
The over extension of the strut was a result of the gradual breakup of the bearings and bearing carriers due to improper/incompatible wear surfaces from the repair facility's improper assembly at overhaul.
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