What happened
On February 4, 2003, an EMB-710C aircraft, registration PT-NMD, was performing a passenger transport flight from a private airstrip at Fazenda São José do “OB” in Tapiratiba, São Paulo, to Passos, Minas Gerais. Shortly after departing the ground, the aircraft experienced a sudden and significant reduction in engine power.
The pilot attempted to abort the takeoff and return to the runway, performing a sharp turn to remain within the pavement limits. However, the aircraft exceeded the runway threshold, descended a 15-meter embankment, and struck the ground in an inverted position. The impact caused an explosion and a subsequent intense fire. The pilot and the three passengers, totaling four fatalities, were killed at the scene. The aircraft was completely destroyed.
The investigation
CENIPA investigators examined the engine and fuel systems to determine the cause of the power loss. Technical analysis of the Lycoming O/5/40B4B5 engine revealed that internal components, including valves, connecting rods, and spark plugs, were free of harmful residues. The magnetos and carburetor also showed no significant abnormalities, and the fuel filter was operating normally.
However, investigators discovered that the fuel selector valve disc was found in a partially engaged, intermediate position. This position restricted the flow of fuel to the engine. While the manufacturer did not require inspections of the internal components of this valve, the investigation focused on whether design deficiencies or mechanical wear caused the disc to jam in this restricted state.
Findings
- The primary contributing factor was a restriction in fuel flow caused by the fuel selector valve disc being stuck in an intermediate position.
- A potential design deficiency in the geometry of the valve disc or the valve assembly may have allowed the mechanism to jam.
- The pilot's recent experience with this specific aircraft type was undetermined, as his last flight in the model had occurred seven months prior to the accident.
- The aircraft was within weight and center of gravity limits at the time of takeoff.