NTSB Identification: MIA99LA137.
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Accident occurred Wednesday, April 21, 1999 in COURTLAND, AL
Probable Cause Approval Date: 11/02/2000
Aircraft: Beech A36, registration: N769LW
Injuries: 1 Serious.

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

During cruise flight, throttle response was not possible and the engine rpm decreased to near idle. While descending for a forced landing with the landing gear extended, the pilot later stated that he could not recall the last several thousand feet of the descent. The airplane collided with trees then the ground. Postaccident examination of the airplane revealed a castellated nut which secures a lever onto the throttle plate shaft was loose by 10.5 turns of the 6 sided nut; no cotter pin was found. This condition would not allow movement of the throttle plate shaft with movement of the throttle control. Postaccident, the engine was removed from the airplane, placed in a test cell, and found to operate normally. Following collapse of the nose landing gear August 1998, the engine and fuel control valve were overhauled. Following the engine overhaul, the engine was test run. The air throttle assembly was then removed for shipping, the lever was loosened, and the engine and boxed air throttle assembly were shipped to where the airplane was being repaired. The air throttle assembly was installed on the engine which was installed into the airplane. The engine was then run and no engine related discrepancies were noted.

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

The failure of maintenance personnel from Signature Flight Support to assure that a cotter pin was installed at the air throttle assembly lever following installation of the overhauled fuel control valve onto the overhauled engine. This resulted in the partial loss of engine power due to the failure of the pilot to adjust the throttle control. A factor in the accident was the premature extension by the pilot of the landing gear which reduced the glide distance.

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