What happened
On July 10, 2019, a Cessna 172N, registration I-DAFE, was conducting a VFR pleasure flight from Venice Lido (LIPV) to Biella Cerrione (LILE). While flying near Pavia, the pilot detected engine abnormalities, specifically engine sputtering and high Exhaust Gas Temperature (EGT). Despite attempts to manage the issue by reducing power to 2000 RPM, the engine malfunction persisted. The pilot declared a "MAYDAY" to the Milan Flight Information Center (FIC) and prepared for an emergency landing. During the approach, the engine ceased operation entirely and the propeller stopped rotating.
The pilot performed an emergency landing in a rice field in Alperolo di Albuzzano, which was covered in approximately 20 cm of water. During the touchdown, the nose gear struck a submerged object, causing the aircraft to nose over. The two occupants, the pilot and a passenger, were able to exit the aircraft without injury.
The investigation
ANSV investigators conducted an on-site inspection of the landing area and the aircraft's recovery location. The investigation revealed that the aircraft's forward section sustained moderate damage from ground contact, while the cockpit and flight instruments remained largely intact. The main landing gear was undamaged, but the nose gear showed significant damage. The engine was examined, and no external damage was noted on visible parts, nor was there evidence of propeller contact with the ground during rotation. Fuel samples from the tanks showed no signs of water or contamination.
A technical analysis of the engine was performed by a certified facility under ANSV supervision. This disassembly revealed that the failure was caused by the fall of the number 2 exhaust valve into the combustion chamber, which resulted in extensive secondary internal damage.
Findings
- The primary cause of the engine failure was the mechanical failure of the number 2 exhaust valve.
- The engine failure led to the forced landing in the marshy terrain.
- While several other minor anomalies were found during engine disassembly (such as missing bolts and improperly secured components), these were not directly linked to the valve failure.