What happened
On August 11, 2007, at approximately 17:30 local time, a Socata Rallye 180-T, registration EC-DTN, was performing a commercial aerial advertising flight near Sanlúcar de Barrameda, Cádiz. The aircraft, operated by Suraviación, was engaged in a mission to tow an advertising banner along the coast. After approximately two and a half hours of flight time, the engine began to sputter, forcing the pilot to release the banner.
In an attempt to resolve the engine instability, the pilot activated the electric fuel pump and cycled the fuel selector valve between the tanks. Despite these efforts, the engine failed to recover power, and the aircraft lost approximately 40 and 500 feet of altitude. The pilot initially attempted to reach a nearby golf course but was forced to perform an emergency landing on a path near a residential area. The aircraft sustained significant damage to the engine mount, cowling, landing gear, and wings, while a perimeter fence was also damaged.
The investigation
The investigation examined the aircraft's fuel system, the pilot's actions, and the flight's operational history. Investigators found that while the total fuel remaining on board was consistent with the flight duration, there was a significant imbalance between the tanks: the left tank was nearly empty, while the right tank contained approximately 75 liters.
Physical inspection of the aircraft revealed the fuel selector was set to the right tank, the throttle was at idle, and the master switch was OFF. The investigation also noted that the flaps were likely not fully extended to the 30° position recommended by the flight manual. Furthermore, the investigation noted that the aircraft was carrying a passenger who was not part of the flight operation.