Accident Air Tractor Inc AT-502 N4556S, Friday 21 September 2012
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Date:Friday 21 September 2012
Time:16:00 LT
Type:Silhouette image of generic AT5T model; specific model in this crash may look slightly different    
Air Tractor Inc AT-502
Owner/operator:Thiel Air Care Inc
Registration: N4556S
MSN: 502-0137
Year of manufacture:1991
Total airframe hrs:10147 hours
Engine model:P&W PT6A SER
Fatalities:Fatalities: 0 / Occupants: 1
Other fatalities:0
Aircraft damage: Substantial
Location:Firebaugh, California -   United States of America
Phase: Initial climb
Departure airport:Firebaugh, CA
Destination airport:Firebaugh, CA
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
The pilot ferried the airplane to a private ag-operating airstrip where it was fully fueled, and 400 gallons of defoliant were loaded in the hopper. During the takeoff roll for the aerial application flight, the pilot noticed that the engine was not producing its full-rated torque, but he chose not to abort the takeoff. The pilot reported that, when the airplane reached the end of the runway, it lifted off but would not climb out of ground effect. As the airplane approached power transmission wires about 0.5 mile from the airstrip, the pilot began dumping the defoliant load to gain altitude. Dumping the load resulted in the airplane gaining some altitude, but, simultaneously, the airplane's nose pitched up, which increased drag and stopped the climb. The airplane struck the wires and landed hard in an open field. Postaccident examination of the engine found no preimpact mechanical anomalies that would have precluded normal engine operation. It is likely that the engine was not producing its full-rated torque because the density altitude was 2,400 feet (as compared to the field elevation of 236 feet), which reduced the available engine torque.

Probable Cause: The pilot's decision to continue the takeoff after the engine stopped producing its full-rated torque while operating in high-density altitude conditions and his subsequent failure to maintain clearance from the power transmission wires.

Accident investigation:
Investigating agency: NTSB
Report number: WPR12LA433
Status: Investigation completed
Duration: 1 year and 8 months
Download report: Final report




Revision history:

04-Oct-2022 10:03 ASN Update Bot Added

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