NTSB Identification: FTW97LA223.
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Accident occurred Friday, June 13, 1997 in BLACK OAK, AR
Probable Cause Approval Date: 06/09/1999
Aircraft: Air Tractor AT-400A, registration: N3161J
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.

Shortly after takeoff, the agricultural airplane lost power. During the forced landing, the airplane was destroyed. Wreckage examination revealed that the propeller blades were in the flat pitch range, bent straight rearward. The blades did not have a twist set nor was there leading edge damage corresponding to powered rotation at impact. Engine examination revealed that all of the blades of the compressor turbine disc were damaged or fragmented. Two of the 58 blades were found fractured at the root and several blade tips showed thermal distress. The compressor disc shroud segment had ballistic indentations corresponding to the fragmented compressor blades. Both power turbine and compressor turbine shroud segments did not show circumferential machining. The fuel filter from the high pressure fuel pump had black residues embedded throughout the filter element. All 58 blades on the compressor turbine disc had been replaced in 1991. No reference was found as to whether or not the replacement blades were new or used parts. The last recorded hot section was in December, 1994, at 7,063.2 hours TSOH. The TSOH at the time of the accident was 7,632.5 hours.

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

The loss of engine power due to compressor turbine blade failure. A factor was the lack of suitable terrain for the forced landing.

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