Pilot Debrief

Air Tractor AT502 near Tappen, ND — 2018-06-28

Final reportCEN18LA249
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Date
2018-06-28
Location
Tappen, ND, USA
Airport
PVT
Aircraft
Air Tractor AT502
Registration
N502S
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Takeoff roll

Probable cause

The partial loss of engine power for reasons that could not be determined based on the available evidence.

NTSB narrative

The pilot reported that he noticed degraded engine performance when the airplane was about halfway down the runway during takeoff for the aerial application flight. Specifically, the engine torque decreased from 1,700 ft-lbs at the start of the takeoff to 1,500 ft-lbs. He determined that there was not enough runway to abort the takeoff and stop the airplane, so he applied full power and dumped the product load. The engine continued to lose power, and the airplane subsequently continued off the end of the runway and nosed over in high vegetation. Postaccident examination of the airplane and engine, including individual testing of several engine components, confirmed that the engine was producing power during the impact sequence, but no determination could be made as to how much power the engine produced. The examination did not reveal any mechanical malfunctions or failures that would have precluded normal operation.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have aborted takeoff when torque dropped to 1500 ft-lbs.

NTSB coding

Evidence available

  • 2 docket documents
View NTSB final reportView NTSB docket

Docket documents2

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