Pilot Debrief

PIPER J3C near Brenham, TX — 2017-01-30

Final reportCEN17LA093
Sign in to save
Date
2017-01-30
Location
Brenham, TX, USA
Airport
11R
Aircraft
PIPER J3C
Registration
N7039H
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Initial climb

Probable cause

The reciprocating engine's exhaust valve being stuck in the “open” position, which resulted in a partial loss of engine power during initial climb.

NTSB narrative

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.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Recognizing engine weakness and aborting takeoff could have prevented the accident.

NTSB coding

Evidence available

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

Docket documents4

Related mishaps