NTSB Identification: FTW01LA178.
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Accident occurred Thursday, August 09, 2001 in Grand Coteau, LA
Probable Cause Approval Date: 02/20/2002
Aircraft: Air Tractor AT-401, registration: N10140
Injuries: 1 Uninjured.
NTSB investigators may have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The agricultural airplane had completed a spray pass from south to north, and during a turn around maneuver, the engine lost power. The pilot emptied the airplane's load and initiated a forced landing to a dirt road; however, the aircraft was unable to reach the road. The airplane touched down in a sweet potato field perpendicular to the rows with its right wing first. Subsequently, as the airplane touched down, its main landing gear collapsed. The airplane came to rest upright. An examination of the engine revealed that the #4 cylinder head had fractured at the exhaust valve rocker arm boss. A review of the maintenance records revealed that on August 4, 2001 (4.4 hours prior to the accident), the Pratt & Whitney R-1340-AN-1 engine's cylinder heads were inspected for cracking in accordance with Airworthiness Directive 99-11-02. No cylinder head cracking was noted.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: the loss of engine power while maneuvering, which resulted from a fractured #4 cylinder head at the exhaust valve rocker arm boss. A contributing factor was the lack of suitable terrain for the forced landing. Full narrative available
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