What happened
On May 10, 2007, a PIPER PA-36, registration EC-CUU, was conducting agricultural spraying operations over oak trees near Añora, Cordoba. During the third flight of the day, approximately 55 minutes into the mission, the aircraft experienced a sudden loss of engine power while climbing out of a spraying run.
Upon noticing the power loss, the pilot engaged the electric fuel pump in an attempt to restore engine power. While this provided a momentary recovery, the power quickly dropped again. Following the aircraft's emergency procedures, the pilot disengaged the electric pump and prepared for an emergency landing. The aircraft impacted a wooded area, resulting in significant damage to the airframe and wings. The main landing gear and tail wheel detached during the impact, and the right wing fuel tank ruptured. The pilot escaped the wreckage without injury.
The investigation
Investigators examined the engine and fuel system components at the crash site and in a workshop. While the left fuel tank remained half full, the right tank was empty due to the rupture. The inspection of the engine revealed that the mechanical fuel pump had completely seized, with a broken axle shaft.
Detailed disassembly of the mechanical pump revealed a broken rotor and a cracked rear cover. Two foreign objects were discovered inside the pump: a piece of plastic and a small metallic fragment. Further inspection of the electric fuel pump revealed that one of its impeller blades had broken and that a positioning pin from the rear cover was missing. The investigation established that the missing pin and the broken blade fragment had been swept through the fuel system into the mechanical pump, causing it to seize.