Accident Beechcraft B200C Super King Air VH-AMM, Wednesday 11 May 1994
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Date:Wednesday 11 May 1994
Type:Silhouette image of generic BE20 model; specific model in this crash may look slightly different    
Beechcraft B200C Super King Air
Owner/operator:New South Wales Department of Health
Registration: VH-AMM
MSN: BL-125
Year of manufacture:1985
Fatalities:Fatalities: 0 / Occupants:
Other fatalities:0
Aircraft damage: Substantial, repaired
Location:Dubbo Airport, NSW (DBO) -   Australia
Phase: Landing
Departure airport:Brewarrina Airport, NSW (BWQ/YBRW)
Destination airport:Dubbo Airport, NSW (DBO/YSDU)
Investigating agency: BASI
Confidence Rating: Accident investigation report completed and information captured
After arriving in the circuit area of Dubbo Airport, Australia, the pilot extended the landing gear and obtained the correct down and locked indications. The right main gear leg subsequently collapsed during the landing roll.
The retract actuator trunnion bearings had collapsed, allowing excessive movement of the actuator in its mount. This resulted in insufficient travel of the actuator to fully engage the downlock. Two separate occurrences involving unsafe landing gear indications, which had been corrected in flight by recycling, had been reported to the operator's maintenance staff prior to the accident. The maintenance staff, unable to duplicate the defect on the ground, had adjusted the downlock switch. Those adjustments finally resulted in the switch jamming in the closed position, giving a safe indication.
The downlock switch has two functions, providing independent safe/unsafe indications of the lock and, in series with the nose and left leg switches, removal of electrical power to the hydraulic pump when the three downlocks are sensed in a locked condition. On the accident flight, with the right downlock switch jammed in the closed position, hydraulic pressure was terminated when the left and nose gears locked down. As the lock function of the right gear lock was compromised because of the failed trunnion bearings, the leg collapsed under the landing loads. Investigation of the aircraft maintenance requirements determined that the landing gear actuator trunnion bearings had been incorrectly identified as sealed bearings requiring no lubrication. The bearings fitted to the aircraft were of the unsealed type, with a requirement for lubrication every 1000 landings or 30 months.

Accident investigation:
Investigating agency: BASI
Report number: 199401233
Status: Investigation completed
Duration: 2 years and 2 months
Download report: Final report



Revision history:


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