Beech BE99 N899AE accident near Cedartown, Georgia

Probable cause

The failure of the left main landing gear bearings and supports due to inadequate lubrication by unknown maintenance personnel.

NTSB analysis

The pilot received an unsafe landing gear indication for the left main landing gear when he configured the airplane for landing. He cycled the gear and then attempted a manual extension, both without success. The pilot then completed the landing on the nose and right main landing gear. A postaccident examination of the left main landing gear actuator revealed that the supports for the actuator bearings lacked lubrication and that the bearings displayed wear due to inadequate lubrication. The overhauled actuator had accumulated 377.5 hours and 285 cycles since overhaul and was installed about 31 months before the accident; the manufacturer's maintenance manual prescribed lubrication of the retract actuator and actuator support bearings every 1,000 cycles or 30 months (whichever occurs first). It could not be determined if inadequate lubrication was applied at installation or if a loss of lubrication was not detected in subsequent inspections. The manufacturer’s maintenance manual cautioned: "When washing the airplane with soap and water, use special care to avoid washing grease away from lubricated area. After washing the wheel well areas with solvent, lubricate all lubrication points. Premature wear of the lubricated surfaces may result if these precautions are not observed."

Text from the NTSB. Open the NTSB docket for ERA11LA239 for the full record.