What happened
On June 29, 2023, a Cessna 152, registration SP-FZY, experienced a significant loss of engine power during the climb phase. The incident occurred while the aircraft was at an altitude of approximately 70 meters AGL. In response to the power loss, the pilot performed an emergency landing straight ahead on the concrete runway of the Rudniki (EPRU) aerodrome, utilizing runway 26. During the final phase of the landing roll, the aircraft veered off the runway. There were no injuries to the crew, and the aircraft sustained no damage.
The investigation
Following the occurrence, an investigation was conducted to identify the mechanical failure. Upon inspecting the engine for malfunctions, investigators discovered a lack of sealing in the second cylinder. After removing the valve covers, the investigation revealed that the locknut for the exhaust valve adjustment screw had become loose. This mechanical shift caused the adjustment screw to move into a position that prevented the exhaust valve from opening.
Findings
- The primary cause of the engine power loss was the loosening of the locknut on the valve clearance adjustment screw, which prevented the exhaust valve from opening.
- Contributing factors included the possibility that the locknut had been tightened with insufficient force during previous maintenance.
- The investigation also noted that the locknut used for the adjustment screw had been previously machined.