What happened
On August 31, 2017, at approximately 21:15, an instructor and a student pilot were conducting a series of VFR night training flights at EPMO. While flying at an altitude of approximately 300 to 400 feet, the student pilot noticed a loss of engine power. The instructor took control of the DA20 as the aircraft continued to climb but began experiencing vibrations and fluctuating temperature readings across the four cylinders.
To maintain airspeed, the instructor established a climb with a 10-degree bank and initiated a left turn. Although the engine was still functioning, the instructor decided to land on the opposite runway (runway 26) to address the technical issue, determining that the situation did not yet necessitate an emergency declaration. Following the landing and a rollout on runway 26, the aircraft taxied via taxiways E and A to the SALT hangar while the engine remained operational.
The investigation
Investigators analyzed data from the aircraft's flight recorder, which confirmed elevated temperatures in the fourth cylinder. The records showed that at the 23-minute mark of the flight, the fourth cylinder ceased operation, resulting in the subsequent loss of engine power. A post-flight inspection of the engine revealed no physical damage to the cylinder bores, piston crowns, or other internal components.
Following the incident, maintenance personnel replaced the fuel injectors, the oil filter, and the oil. Subsequent engine tests confirmed that the aircraft was fit for continued operation.
Findings
- The loss of power and the rise in temperature in the fourth cylinder were caused by the progressive degradation of a fuel injector's performance.
- This degradation led to a lean fuel-air mixture, which eventually caused the fourth cylinder to fail.