ATL99LA086

While on approach, the pilot placed the landing-gear handle in the down position but the right main gear did not extend. All attempts to extend the right main gear failed. The pilot landed on the left main gear and the nose wheel. The right wing settled to the runway and the airplane veered off the right side of the runway and collided with a ditch. A post-accident inspection of the landing gear system by the FAA revealed that the right main gear drive shaft had been sheared, disabling the actuator. Examination of the actuator parts revealed that the ring gear was missing one tooth and the pinion gear, which meshes with the ring gear, had missing and damaged teeth. Examination of the upper and lower thrust bearings revealed that the lower thrust bearing had been installed in reverse. The type of damage the ring and pinion gears exhibited indicated that the gears were not meshing properly. A thrust bearing installed in reverse could create an interference condition between the gears.

On May 14, 1999, at 0003 eastern daylight time, a Beech BE-100, N924RM, landed on runway 6 with the right main gear up, veered off the runway, and collided with a ditch at the Hickory Regional Airport in Hickory, North Carolina. The business flight was operated by the pilot under the provisions of Title 14 CFR Part 91 with an instrument flight plan filed. Visual weather conditions prevailed at the time of the accident. The air transport pilot, the right seat passenger/pilot, and the two passengers were not injured. The airplane sustained substantial damage. The flight departed Richmond, Virginia, at 2150.

As the flight approached Hickory, the pilot was issued a visual approach clearance. Upon entering the traffic pattern for a full stop landing, the pilot completed the before-landing checklist, which included lowering the landing gear. When the landing-gear handle was placed in the down position, the right main landing gear did not extend. The pilot and the right seat passenger/pilot attempted several times to lower the right main gear but failed. The pilot decided to land with all gear in the up position; however, the left main gear and the nose wheel did not retract when the gear handle was placed in the up position. The airplane landed on the left main landing gear and the nose wheel. As the speed of the airplane slowed, the right wing settled to the runway and the airplane veered off the right side of the runway. The airplane came to rest after colliding with a five-foot deep ditch.

A post-accident inspection of the landing gear system by the FAA revealed that the right main gear drive shaft had been sheared. The right main landing gear actuator was removed and disassembled under the supervision of the FAA. Prior to disassembling the actuator gearbox, it was observed that the input shaft could be freely rotated and the output shaft did not move. The actuator parts were sent to Engineering Systems Inc. for examination. Examination of the ring gear and pinion gear revealed that the ring gear was missing one tooth and the pinion gear, which meshes with the ring gear, had missing and damaged teeth. Examination of the lower thrust bearing and the upper thrust bearing revealed that each was heavily packed with grease on one side. The heavily greased side of the bearings would have been facing the ring and pinion gears in the gearbox. The side of the bearing marked "Thrust" should be installed facing away from the ring and pinion gears. The lower thrust bearing was heavily greased on the side marked "Thrust" and there were small chips of metal embedded in the grease. The upper thrust bearing was greased on the side not marked "Thrust." The last inspection/maintenance done on the main landing gear actuators was performed on November 22, 1996 at 9508.6 hours aircraft total time and 9,279 landings.