NTSB Identification: MIA99LA233.
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Accident occurred Saturday, August 21, 1999 in MIAMI, FL
Probable Cause Approval Date: 03/02/2001
Aircraft: Cessna 172RG, registration: N6231V
Injuries: 2 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The pilot stated that after takeoff while climbing through 500 feet, the airplane abruptly and uncommanded, yawed to the left. He attempted to correct with rudder trim but the trim wheel turned freely. The flight remained in the traffic pattern and while on short final approach, the controller advised the pilot to go-around as the landing gear was not extended. The pilot lowered the landing gear but landed before the main landing gear locked in place. He stated that he heard the gear warning horn while on short final approach with the flaps extended. Post accident examination of the airplane revealed that a wire at the micro-switch for the throttle gear warning was broken; the wire was reconnected and the warning horn operated normally. The rudder trim actuator and trim wheel were fully displaced to the left, and the master link for the rudder trim chain was noted to be bent and the master link lock clip was fractured. Metallurgical examination of the lock clip revealed it failed due to overstress failure. Post accident retraction and extension tests of the landing gear revealed no evidence of preimpact failure or malfunction.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The delay by the pilot-in-command to extend the gear resulting in collapse of the main landing gear after touchdown. Factors in the accident were the inoperative gear warning system associated with the throttle due to the broken wire at the throttle microswitch, and the overstress failure of the rudder trim chain master link clip which resulted in disconnection of the rudder trim while trimmed full left.

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