What happened
On March 20, 2009, an EMB-711 C, registration PT-NBH, was performing a visual flight rules (VFR) flight from Floriano to Nossa Senhora de Fátima, Piauí. Approximately fifteen minutes into the flight, the pilot noticed irregular engine operation characterized by fluctuations in fuel flow.
To stabilize the engine, the pilot activated the electric fuel pump, which temporarily normalized the engine's performance. However, after receiving radio communication from a mechanic in another aircraft suggesting that the electric pump could fail unexpectedly, the pilot decided to perform a precautionary landing. The aircraft landed on the BR 343 highway near Água Branca. The pilot waited for a gap in traffic to ensure a safe touchdown. Both the pilot and the passenger were uninjured, and the aircraft sustained no damage.
The investigation
CENIPA investigators examined the mechanical fuel pump and found that the diaphragm was dried out and exhibited visible cracks, which had caused the fuel flow instability. The investigation also revealed a lack of proper component traceability; while maintenance records indicated the installation of one specific pump, the actual component installed was identified by a different certification number.
Furthermore, the investigation noted that the pilot had been unable to establish radio contact with Teresina Approach or Recife Center during the flight. The investigation also assessed the pilot's decision-making process, noting that the engine had returned to normal operation after using the electric pump, suggesting that a landing at a nearby airport might have been possible.
Findings
- The primary cause of the fuel irregularity was a degraded mechanical fuel pump diaphragm containing visible cracks.
- The pilot's decision-making was identified as a contributing factor, as the pilot chose a highway landing instead of proceeding to an available airfield after the engine stabilized.
- Inadequate maintenance traceability regarding the fuel pump component contributed to the presence of a potentially unairworthy part.
- Lack of technical knowledge regarding the specific fuel system characteristics led to an incorrect risk assessment by the pilot.
- Inadequate management oversight by the operator regarding maintenance and operational monitoring was also noted.