Cessna 172P N52492 accident near San Jose, California

Probable cause

The pilot's delayed decision to execute an emergency landing and his attempt to return to the airport following a partial loss of power due to wear on internal engine components, which prevented the engine from developing full-rated power during the airplane's initial climb.

NTSB analysis

The pilot reported that during the takeoff for the personal flight, as the airplane reached about 50 ft above ground level, the airplane stopped climbing and the pilot was unable to maintain altitude. When the airplane stopped climbing, the pilot and pilot-rated passenger decided to examine the anomaly further as the pilot began a wide, shallow left turn and attempted to maintain altitude. A video showed that as the airplane completed the turn, it entered a steep bank angle and descended. The airplane's wings leveled out just before the airplane disappeared behind trees and impacted a trailer, trees, and a residence, which resulted in substantial damage to the wings, empennage, and fuselage. Examination of the area revealed that, had the pilot initiated an emergency landing straight ahead rather than troubleshooting the engine problem or attempting to return to the airport, the damage may have been reduced.

Postaccident examination of the engine revealed the travel of two of the intake valve rockers was severely limited, the camshaft lobe that supported these intake valves was severely worn and had extensive pitting, and spalling damage was on the faces of the camshaft lifters supporting these intake valves. The decreased travel of the intake valves would have reduced the fuel/air mixture reaching the affected cylinders, thus reducing the overall power the engine could produce.

A review of maintenance records revealed that owner had not complied with a manufacturer's mandatory service bulletin requiring a rocker arm inspection. While a service bulletin is not mandatory for Part 91 airplane owners, compliance with the service bulletin might have revealed the limited travel of the rocker arms and prevented the loss of engine power.

Text from the NTSB. Open the NTSB docket for WPR18LA034 for the full record.