Aviation safety investigations & reports

Mooney M20J, VH-UDD, Bankstown NSW, 11 March 1987

Investigation number:
Status: Completed
Investigation completed


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As part of a refresher check on the aircraft, the instructor required the pilot to use the manual system for lowering the landing gear. After turning the crank handle the recommended number of turns the gear down light did not illuminate. The pilot continued to rotate the crank handle a few more turns and a loud bang was heard, following which there was little resistance to crank handle movement. However, the gear down light still did not illuminate although the visual gear position indicator in the cockpit did indicate that the gear was in the down position. The gear actuator circuit breaker was reset and the gear selected up; the gear did not retract but the gear unsafe light illuminated. All further attempts to obtain a gear down light were unsuccessful. Observations made from another aircraft and by persons on the ground indicated that the gear was down and locked. The aircraft was diverted to Bankstown and the gear collapsed immediately after touchdown. A fault in the gear indicating system prevented illumination of the gear down light when the gear reached the down and locked position on the initial manual extension. When the crank handle was wound further, an overload failure of the actuator housing occurred. The gear was unlocked when the up selection was made but the damaged actuator prevented either retraction or safe extension. The actuator has a vital function in retaining the gear in the down and locked position as it pre-loads the landing gear braces in an overcentre position. Once the actuator was damaged, gear collapse on landing was inevitable.

Download Final Report
[Download  PDF: 22KB]
General details
Date: 11 March 1987   Investigation status: Completed  
Time: 1800 approx    
Location: Bankstown    
State: New South Wales   Occurrence type: Wheels up landing  
Release date: 03 December 1987   Occurrence category: Accident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer Mooney Aircraft Corp  
Aircraft model M20  
Aircraft registration VH-UDD  
Type of operation Flying Training  
Damage to aircraft Substantial  
Departure point Hoxton Park NSW  
Departure time 1800 approx  
Destination Hoxton Park NSW