What happened
On September 24, 2010, an EMB-721C, registration PT-EGM, operated by Táxi-Aéreo Sul do Pará Ltda., was performing a ferry flight from Belém to Marabá, Brazil. The aircraft had recently undergone a 500-hour inspection at a maintenance facility.
Shortly after takeoff from the Brigadeiro Protásio de Oliveira Aerodrome (SBJC), the pilot experienced a loss of engine power. In response to the power loss, the pilot executed a forced landing ahead of the runway. The aircraft landed with its landing gear retracted, approximately 127 meters past the end of runway 33, within the aerodrome's perimeter. The aircraft traveled an additional 102 meters after initial contact with the ground before colliding with and breaching the aerodrome's perimeter wall. The impact caused the wings to be torn from the fuselage, resulting in severe damage to the aircraft structure, including the engine, propeller, and wing spars.
The investigation
CENIPA's investigation focused on the engine's performance and the maintenance quality following the recent 500-hour inspection. While the engine's internal components showed no defects, technical examinations of the ignition and fuel systems revealed several critical issues.
Testing of the ignition system identified that the magneto's internal timing was inconsistent with the manufacturer's manual. Furthermore, the ignition wiring exhibited high-voltage leakage, and several spark plugs were found to be malfunctioning or improperly calibrated. Regarding the fuel injection system, investigators detected small particles at the diaphragm base, which likely caused wear on the cut-off control plate, leading to an excessively rich air-fuel mixture.
Findings
- Improper maintenance procedures: The maintenance facility failed to follow manufacturer manuals during the 500-hour inspection, specifically regarding magneto timing, ignition harness testing, and spark plug inspection.
- Inadequate supervision: The maintenance facility did not provide sufficient oversight of the inspection tasks, and the operator failed to implement a formal inspection checklist when the pilot took delivery of the aircraft following maintenance.
- Ignition system failure: The engine power loss was contributed to by incorrect magneto timing and faulty ignition wiring.
- Fuel system deficiency: Evidence of particulate contamination in the fuel injection diaphragm contributed to an improper air-fuel mixture.