Pilot Debrief

AIR TRACTOR INC AT-502 near Lewistown, MT — 2011-06-25

Final reportWPR11LA288
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Date
2011-06-25
Location
Lewistown, MT, USA
Aircraft
AIR TRACTOR INC AT-502
Registration
N1022N
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Cruise

Probable cause

The fatigue fracture and separation of the fuel bypass line, which resulted in a total loss of engine power.

NTSB narrative

The pilot reported that while in cruise flight about 800 feet above ground level, the engine lost power, and he initiated a forced landing to an area of open, uneven terrain. During the landing roll, the left wing struck the ground and the airplane ground looped. Postaccident examination revealed that the fuel bypass line was fractured and had separated from the fuel control unit. Metallurgical analysis revealed that the fuel bypass line fractured near a ferrule at the edge of the braze filler metal fillet. Striations on the fracture surface were consistent with a fatigue crack originating on the outside surface of the tube and propagating toward the inside surface and circumferentially around the tube wall. No maintenance records for the airplane were recovered during the course of the investigation, and, therefore, the amount of time and maintenance history on the line was undetermined.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have checked engine components before flight to prevent failure.

NTSB coding

Evidence available

  • Photos
  • 3 docket documents
View NTSB final reportView NTSB docket

Docket documents3

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