Introduction
On 5 April 2002 at 12:15 local time, a Cessna 152 (registration EC-FGP) sustained substantial damage when it made an emergency landing on a beach adjacent to the port of Les Cases d'Alcanar, Tarragona. The aircraft was manufactured in 1978 and powered by a single Lycoming O-235-L2C engine. The sole pilot and one passenger were uninjured.
Flight and Emergency Landing
The aircraft had departed from Reus airport for a local flight. While near the town of Sant Carles de la Rapita, the engine power dropped to nearly zero. The pilot executed an emergency landing on the beach alongside the port, rolling along the sand and coming to a stop where waves were breaking. The aircraft sustained damage to the engine, propeller, right wing, and landing gear.
Investigation
Post-accident inspection revealed that the outside temperature was approximately 20°C. The aircraft had more than 80 liters of fuel remaining. The engine was running at the moment of impact, with the first contact occurring on the right wing leading edge, followed by the nose wheel. No anomalies were found when the fuel system and electrical system were disassembled at a maintenance center.
Pilot's Account
The pilot reported filing a local flight plan and removing the aircraft from the hangar. He checked the oil level and drained fuel from the wing tanks and engine filter, finding no contamination or water. He then refuelled to capacity and confirmed the fuel caps were secured. During engine start at approximately 1000 RPM, the engine stopped after 10-15 seconds. After a restart at 1500 RPM, the engine operated normally. At the runway 25 holding point, engine run-up checks were satisfactory, and takeoff parameters were normal.
About 30 minutes after departure, while at 1300 feet indicated altitude near Sant Carles de la Rapita, the pilot decided to descend to 800 feet along the coastline. He applied carburetor heat and reduced power to about 1700 RPM. Upon reaching the desired altitude, he increased power; immediately, the RPM dropped until the engine nearly stopped. He removed carburetor heat and cycled the throttle, obtaining three or four brief engine responses with no continuity. With altitude lost and no sustained power, the pilot selected a beach section free of people and obstacles for an emergency landing, choosing the wave zone for its smoother surface.
Aircraft Manual Guidance
The aircraft flight manual specifies that carburetor heat should be used during the "before landing" procedure (descent in approach) but not during a "balked landing" (go-around). The pilot's descent was more comparable to a balked landing as the intention was not to land. Manuals for similar aircraft with identical engines and carburetor heat systems advise against using carburetor heat in such maneuvers except in icing conditions. In this case, there was virtually no possibility of icing. Generally, carburetor heat is not recommended except for icing or very steep descents with high vertical speed, which did not apply here.
Probable Cause
The most probable cause of the accident is that the engine could not deliver the required power because the carburetor heat was on. Under the circumstances, carburetor heat was not necessary. The heated air entering the carburetor had lower density, resulting in an excessively rich mixture that choked the engine, preventing it from increasing RPM.