What happened
On October 27, 2008, a Robinson R22 helicopter, registration PT-YLO, was conducting an instructional flight from Campo de Marte (SBMT) to a helipad in Arujá (SSUO). The flight, part of a private pilot training program, included various maneuvers and a planned return to the departure airfield.
After approximately one hour and ten minutes of flight time, while overflying the Tietê Ecological Park during the return leg, the aircraft experienced a loss of engine power. The instructor took control and initiated an autorotation to perform an emergency landing on the side of the Ayrton Sen/Senna highway. During the descent, the tail rotor struck a tree, causing the pilot to lose control and resulting in a hard impact with the ground. Both the instructor and the student were uninjured, though the aircraft sustained severe damage to the main rotor, tail rotor, 90-degree gearbox, and skids.
The investigation
The CENIPA investigation focused on determining the cause of the engine power loss. Post-accident inspections of the engine, both internal and external, revealed no mechanical defects or findings that could explain the loss of power. The investigation also examined the aircraft's fueling process, noting that the refueling had been performed by ground personnel without direct supervision by the flight crew. The investigation considered the possibility of fuel exhaustion, as the flight duration had exceeded the typical one-hour mission profile, and the crew had not personally verified the fuel levels during the refueling process.
Findings
- The most probable cause of the engine failure was fuel exhaustion.
- The instructor may have failed to perform periodic fuel checks during the instructional flight.
- There was a lack of direct supervision during the refueling process, as the pilots did not personally monitor the fuel load.
- The decision to extend the mission to Arujá increased the flight duration and the instructor's workload, potentially impacting situational awareness.
- The refueling was performed by support staff who may have prepared the aircraft for a standard one-hour mission rather than the extended duration required for this specific flight.