Accident Overview
On January 30, 2017, at approximately 1538 central standard time, a Piper J3C airplane, registration N7039H, sustained substantial damage during a forced landing following a partial loss of engine power. The incident occurred during initial climb after takeoff near Brenham, Texas. The aircraft was operated by the student pilot under 14 CFR Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan was filed. The flight was originating at the time for an unconfirmed destination.
Pilot Actions
According to the flight instructor, pre-takeoff engine checks were normal. During the takeoff, both the flight instructor and the student pilot noticed that the engine felt "weak," but attributed this to being unaccustomed to the airplane. The flight instructor verified that the magneto switch was in the "both" position, the primer was locked, and the carburetor heat was off. By that time, the remaining usable runway had been exhausted, and the airplane was sinking with full throttle applied. The instructor selected a field for landing, but the airplane impacted the top of a tree and then the ground during the forced landing.
Post-Accident Examination
Examination of the airplane by a Federal Aviation Administration Inspector revealed that the exhaust valve for the No. 4 cylinder was stuck in the open position due to excessive deposits from the combustion process. The airplane's fuselage and wings were damaged during the forced landing. The student pilot and flight instructor were not injured.