Beech 200 N8170J accident near Gulfport, Mississippi

Probable cause

The failure of the right main landing gear actuator, which led to a gear-up landing.

NTSB analysis

The airplane was on an instrument approach when the pilot attempted to extend the landing gear. During the gear extension process, the passengers heard a “loud bang” under the floor panels, and the pilot reported that the gear would not extend. The pilot diverted to another airport and attempted to extend the landing gear manually, which was unsuccessful as the landing gear system was jammed. The pilot landed with the gear retracted and the airplane sustained substantial damage to the fuselage and empennage.

A postaccident examination of the landing gear revealed that the gear was still jammed and could not be actuated with the gear handle or by manual extension. The right landing gear drive shaft was unable to rotate and exhibited a binding during the rotation attempt. The examination and disassembly of the right main landing gear actuator revealed that the initial failure originated between the bevel gear set. The pinion gear and driven gear exhibited damage and fractures of their respective teeth. The cracked teeth and pitch line pitting present on the pinion gear indicate that it exhibited fatigue wear prior to the failure of the bevel gears. The final surface of the driven gear was significantly smeared, which obstructed the examination and analysis of the surfaces for fatigue-like cracks and wear patterns. Although the failure was within the bevel gear set, the initiating gear failure could not be determined due to the damage.

The pinion gear had effective case depth but did not meet the drawing requirements for minimum case hardness. The driven gear did not show evidence of case hardening and did not meet the drawing requirements for both effective case depth and minimum case hardness. Since the bevel gear set were operational for more than 12,000 cycles, it is likely that the case hardness did not contribute to the gear failure.

Text from the NTSB. Open the NTSB docket for CEN22LA138 for the full record.