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Aviation Accident

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NTSB Identification: CEN17LA093
14 CFR Part 91: General Aviation
Accident occurred Monday, January 30, 2017 in Brenham, TX
Probable Cause Approval Date: 09/06/2017
Aircraft: PIPER J3C, registration: N7039H
Injuries: 2 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The student pilot and flight instructor were conducting a personal flight. The flight instructor reported that the pretakeoff checks were “normal” but that, during the takeoff, the engine felt “weak” and that the engine lost power during the initial climb. The flight instructor conducted a forced landing to a field, during which the airplane impacted the top of a tree and then the ground.
Examination of the airplane revealed that the exhaust valve for the No. 4 cylinder was stuck in the “open” position possibly due to excessive deposits from the combustion process. It is likely that the stuck exhaust valve resulted in the partial loss of engine power reported by the flight instructor.


The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
  • The reciprocating engine's exhaust valve being stuck in the “open” position, which resulted in a partial loss of engine power during initial climb.