Beech 95 B55 (T42A) N321BJ accident near Cameron Park, California

Probable cause

Failure of the landing gear to extend as a result of excessive wear within the landing gear gearbox and motor, which resulted in a gear-up landing.

NTSB analysis

The pilot reported that he heard a loud crunch when he raised the landing gear shortly after takeoff. The pilot climbed the airplane to about 3,000 ft and attempted to lower the landing gear using both the normal and emergency gear extension procedures but was unable to do so and subsequently landed with the gear retracted, resulting in substantial damage to the lower fuselage.

Examination revealed that the landing would not extend normally. The landing gear motor was found shorted out internally and the gearbox sector gear contacted the internal stop when retracted; therefore, the emergency gear handle was not in contact with the pinion and rotated freely. The crank assembly exhibited signs of excessive wear and excessive pinion shaft end play. The American Bonanza Society Air Safety Foundation’s Landing Gear Inspection Checklist and Repair Guide stated that, “if the sector gear [end] hits the stop in either the extended or retracted position, the gearbox and motor should be removed and overhauled. The most common cause of this condition is a gear motor that is due for overhaul.”

The excessive wear within the gearbox caused the sector gear to lose contact with the pinion which caused the gear motor and emergency gear handle to rotate freely with no corresponding motion from the landing gear itself.

Text from the NTSB. Open the NTSB docket for WPR17LA061 for the full record.