What happened
On February 18, 2020, a Pelican GS, registration EC-YTL, departed from runway 34 at the Mérida-Royanejos airfield (LEMY) for a local flight. The aircraft was occupied by a pilot and a more experienced passenger, who had previously agreed on emergency procedures, including the passenger taking control if necessary.
During the initial climb, the engine experienced a sudden drop in RPM accompanied by severe vibrations. Following their pre-flight agreement, the passenger took control, stating "mine," and retarded the throttle to reduce the vibration to an acceptable level. The passenger then initiated a gentle right turn to return to the airfield and land on the opposite runway (16).
The aircraft approached the field from the northeast. Due to low airspeed, the passenger decided not to attempt a final turn to align with the runway to avoid a potential stall. The aircraft crossed the runway and landed on the adjacent terrain. Because the landing area was waterlogged and soft, the nose gear collapsed immediately upon impact. The aircraft slid on its nose and main gear for approximately 60 meters before coming to a stop. Both occupants were uninjured and evacuated the aircraft independently.
The investigation
Investigators examined the engine and fuel system to determine the cause of the power loss. While the fuel itself met all 95 octane specifications, the inspection of the carburetors revealed that the left float chamber was full, while the right chamber was nearly empty.
Further examination of the right carburetor chamber showed a significant accumulation of dirt particles. Notably, some of these particles were larger than the mesh of the fuel filter located before the mechanical pump, meaning they could not have originated from the fuel tanks. The investigation focused on the fuel lines, which had been recently replaced during a major maintenance overhaul.
Findings
- The engine failure was caused by an interruption of fuel supply to the right carburetor.
- The investigation established that dirt particles had entered the fuel system, likely during recent maintenance tasks.
- The presence of large contaminants in the carburetor chamber, which could not have passed through the fuel filter, indicates that the contamination occurred after the filter but before the components were fully assembled.
- The emergency landing on muddy ground was the direct cause of the nose gear failure and subsequent aircraft damage.