NTSB Identification: LAX05LA159.
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Accident occurred Saturday, May 07, 2005 in Tucson, AZ
Probable Cause Approval Date: 05/30/2006
Aircraft: Beech 23, registration: N2388Q
Injuries: 1 Minor.

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 engine lost power during the takeoff initial climb and the airplane was damaged during a forced landing. The run-up check was uneventful. When the airplane was about 400 feet above ground level turning the left crosswind leg of the airport traffic pattern, the engine lost power completely. The pilot made a forced landing between a taxiway and the perimeter fence on the airport. Post accident test-run of the engine revealed that the mixture control cable was fractured 0.35 inches from the set screw, which attaches it to the carburetor, and the carburetor mixture arm was free to move, uncommanded. This fracture was hidden by the outer sheath that covers the mixture control cable and movement of the cockpit mixture control did not produce corresponding movement of the carburetor mixture arm. With the fracture surfaces realigned, the wire appeared to have been bent nearly 90 degrees from its normally straight path. A scanning electron microscopy (SEM) of both fracture surfaces of the wire revealed the existence of a fatigue crack about 1/4 of the wire's cross-sectional area and perpendicular to the wire's surface. The origin of the fatigue crack was on the outside surface of the 90-degree bend in the wire, which suggests that the crack initiated and propagated during service while the main portion of the wire was under compression loads. The presence of the fatigue crack is indicative of an installation problem, such as overtorquing of the set screw. The fracture of this cable would not allow the pilot to properly set the mixture from the cockpit control to the carburetor.

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

a loss of engine power due to the fatigue fracture and separation of the mixture control cable. The fatigue crack resulted from inadequate installation techniques by unknown maintenance personnel.

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