Cessna 150L N16071 accident near Elberton, Georgia

Probable cause

The pilot’s decision to take off with a known engine issue, which resulted in a partial loss of power on the initial climb due to the No. 1 cylinder’s exhaust valve becoming stuck. Contributing to the outcome, was the pilot’s delay in aborting the takeoff.

NTSB analysis

The pilot reported that while taxiing before the flight, the engine had “skipped,” but normal power was regained during the run-up, so he decided to take off. The pilot reported that during the initial climb, the engine sustained a partial loss of power. He reported that, after the partial loss of power, he became fixated on the throttle and mixture and keeping the wings level. Subsequently, he realized he had traveled too far down the runway to abort the takeoff. He reduced the pitch attitude, navigated towards an open grassy area between trees, and lowered flaps to 40°. During the touchdown, the left wing abruptly dropped and impacted the ground and the airplane nosed over during the roll out. The fuselage, wings, and empennage sustained substantial damage.

Multiple witnesses described that during the taxi and takeoff, the engine was running rough and skipping, and that the airplane struggled to gain altitude. Airport surveillance video captured most of the takeoff and initial climb. The video was consistent with the witness reports that the airplane struggled to climb throughout the entirety of the takeoff and initial climb, before disappearing out of view.

Postaccident examination of the engine revealed that the No. 1 cylinder exhaust valve was stuck. There were no other anomalies observed with the airplane or engine.

The pilot reported that in the few days preceding the accident, he had experienced multiple partial losses of engine power. He changed the spark plugs the day before the accident and the accident flight was the first flight after that maintenance. It is likely that the repeated engine skipping and partial losses of power the pilot experienced were evidence of a sticking valve, which ultimately became stuck during the accident flight.

Had the pilot decided to allow a mechanic to examine the repeated engine issues more thoroughly, the stuck/sticking valve may have been properly diagnosed. Further contributing to the outcome was the pilot’s continuation of the takeoff roll and initial climb despite the opportunity to abort the takeoff and land on the remaining runway surface.

Text from the NTSB. Open the NTSB docket for ERA23LA297 for the full record.