Incident Overview
On June 26, 2003, at approximately 11:55 UTC, a Cessna F-152, registration CS-AYG, departed from Runway 35 of Cascais Municipal Aerodrome for a solo navigation training flight. The intended route was from Cascais (LPCS) to Santarém (LPSR) and Santa Cruz (LPSC), returning to Cascais. The aircraft was operated by OMNI – Aviação e Tecnologia and owned by Comercial Leasing, S.A.
Flight History
Shortly after liftoff, at about 700 feet altitude, the pilot noticed a sudden reduction in engine RPM accompanied by strong vibrations throughout the aircraft. The pilot immediately advanced the throttle, confirmed rich mixture, and set carburetor heat to maximum cold, but the engine remained at approximately 600–650 RPM. The pilot decided to perform a tight traffic pattern and return to the aerodrome, reporting a partial engine failure to the control tower and requesting landing priority, which was granted.
During final approach to Runway 35, another pilot in the area reported seeing smoke emanating from the CS-AYG. The pilot declared an emergency and continued the approach. The tower controller alerted emergency services, which positioned themselves along the runway. The pilot landed without incident and, on instruction from the tower, stopped the aircraft on the taxiway and shut down the engine. The smoke ceased once the engine was stopped. Emergency services did not intervene as no fire was present. The aircraft was subsequently towed to the maintenance hangar.
Aircraft and Engine Examination
The pilot, the sole occupant, was uninjured. The aircraft sustained no structural damage, although the left side of the fuselage was soiled by oil that had leaked from the engine breather. Following the incident, the engine (Textron Lycoming O-235-L2C, serial RL-19462-15) was examined by technicians from AEROMEC. Cylinder #2 showed no compression, and disassembly revealed extensive damage: the piston rings and piston head were fractured, with deformation indicating overheating. The engine had been overhauled in 2002 and installed on the aircraft on May 28, 2003, accumulating approximately 135 hours and 50 minutes at the time of the incident.
Conclusions
The investigation determined that the partial power loss resulted from a structural failure of the engine due to fracture of the piston rings and piston head of cylinder #2, caused by overheating that occurred before or during the engine's introduction into service. A contributing factor was a delay in the engine overhaul.
Note: No analysis, causal links, or recommendations beyond those explicitly stated in the source have been added.