What happened
On April 5, 1998, an AS-350B Esquilo, registration PT-YHM, operated by Merisa S/A, was performing a series of shuttle flights between Hotel do Frade and Parati, Rio de Janeiro. After completing three flight segments, the pilot decided to proceed to Angra dos Reis to refuel. While crossing Baía da Ribeira near Ilha do Caveral, the engine failed in flight. The pilot attempted an emergency landing on the water, but the helicopter struck the sea at a 45-degree nose-down angle and a 30-degree lateral tilt. The aircraft submerged and remained underwater for four days. The pilot, who was not wearing seatbelts/harnesses at the time of impact, died at the scene.
The investigation
CENIPA investigators examined the wreckage recovered from the seabed four days after the accident. The investigation focused on the engine's performance and the fuel system status. Analysis of the debris showed no technical failures in the flight controls or power transmission systems. However, evidence indicated the engine was not producing full power at the time of impact. The fuel level float was found in the lowest possible position, indicating the tanks were nearly empty. Passengers on the previous flight segment reported that the low-fuel warning light (the "COMB" light) had already been illuminated well before the decision to fly to Angra dos Reis. The investigation also noted that while the aircraft had sufficient altitude and airspeed to perform an autorotation, the pilot failed to execute the maneuver correctly.
Findings
- Fuel Exhaustion: The engine failure was likely caused by a lack of fuel, as evidenced by the fuel float position and passenger testimony regarding the low-fuel warning.
- Deficient Planning: The pilot failed to plan the mission with sufficient fuel reserves to account for the high consumption during takeoff, landing, and ground idling.
- Poor Decision Making: The pilot incorrectly assessed the situation by continuing flight operations despite the low-fuel warning light being active.
- Human Factors: An excess of confidence, stemming from the pilot's significant experience, contributed to the error in evaluating flight conditions and the decision to proceed with insufficient fuel.
- Operational Errors: The pilot failed to properly apply the necessary controls to execute a safe autorotation maneuver and was not wearing the required safety harnesses during the impact.