On June 6, 1991, a Cessna 310L (registration N3337X) operated by Edward C. Hartung was involved in an aviation accident near Fort Wayne, IN. Investigators recorded the probable cause as: THE IMPROPER INSTALLATION OF A BEARING BY MAINTENANCE PERSONNEL. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During landing gear extension, the right main gear failed to deploy, prompting a two-wheel landing. Investigation revealed an incorrectly installed inner bearing caused the strut to overextend and jam.
Event Description
When the pilot selected the landing gear down, the right main landing gear remained retracted. The pilot subsequently executed a landing on the two remaining wheels. Examination of the hung gear provided insight into the mechanical failure.
Examination Results
The right main gear strut piston assembly was found with its external lock ring unseated. This allowed the strut to overextend and become jammed within its well. The root of the issue traced to the inner bearing mounted adjacent to the lock ring groove: it had been installed in reverse orientation. Inspection of the opposite landing gear revealed that its inner bearing was also installed backwards.
Both inner bearings were new components that had been replaced five days before the incident during the completion of an airworthiness directive. The manufacturer's service manual includes instructions specifying the correct orientation for these bearings.