Incident Overview
A Beech 95-B55 airplane sustained substantial damage during a wheels-up landing after the crew was unable to extend the landing gear. The certified flight instructor (CFI) reported that on the downwind leg, the landing gear did not fully extend and the gear-down indicator lights did not illuminate. An attempt to retract the gear also failed, as the gear-up light did not illuminate.
Attempted Extensions and Smoke
The crew attempted to extend the landing gear again, but the cabin began filling with smoke, and both the gear motor and right generator circuit breakers tripped. The CFI then performed the manual gear extension procedure without success, stating that "The manual gear extension handle was not catching anything and turning very loosely." The crew subsequently landed with the landing gear retracted, and during the landing roll, the airplane impacted a runway sign.
Post-Accident Examination
After the accident, the landing gear extension and retraction system was examined with the airplane elevated on jackstands. Neither the electric nor the manual gear extension procedures were able to extend the landing gear. The landing gear extension and retraction gearbox was removed and disassembled for further inspection.
Gearbox Findings
Inside the gearbox, one of the actuator worm gear bearings was found in several pieces. This caused the worm gear to become lodged between the sector gear and the gearbox housing. According to the Beech 95-B55 maintenance manual, the gearbox is to be replaced or overhauled every 2,000 hours. The accident airplane's gearbox had accumulated 2,137 hours since its last overhaul and 6,342 hours since new.