What happened
On October 31, 2012, an HB-350B helicopter, registration PT-HNE, was performing a transport flight from Sorocaba to a helipad at the Cia. Brasileira de Alumínio (SIVX) in Alumínio, São Paulo. The flight, which originally began as a single-passenger shuttle, was modified mid-route when the operator requested the transport of five additional passengers.
During the final approach to the helipad, the pilot experienced a drop in engine RPM approximately 15 meters above the ground. In an attempt to maintain control, the pilot reduced collective pitch, but subsequently increased it to cushion the landing. Due to insufficient power, the aircraft touched down with excessive energy, causing the right skid to break and the tail rotor blades to strike the ground. The helicopter slid approximately 10 meters, colliding with a fire equipment box. All six occupants (the pilot and five passengers) escaped without injury, though the aircraft sustained substantial damage to the tail boom, tail rotor, and landing gear.
The investigation
CENIPA investigators determined that the aircraft was operating significantly above its certified Maximum Takeoff Weight (MTOW). Calculations revealed the helicopter was approximately 119 kg overweight at departure from Sorocaba. The investigation found that the pilot had not consulted the performance charts in the Flight Manual to verify weight and balance or the impact of environmental conditions.
Environmental factors played a critical role. The high temperature (34°C) and the elevation of the landing site resulted in a high density altitude of 5,300 feet. This high density altitude significantly reduced engine performance and aerodynamic lift. Investigators ruled out mechanical failure of the powerplant, as all rotating components were functional and no debris was found in the magnetic plugs.
Findings
- Operating above maximum takeoff weight was the primary cause of the loss of performance.
- Inadequate flight planning, specifically the failure to recalculate performance for the additional passengers.
- Poor pilot judgment regarding the risks of operating in high density altitude conditions.
- Flight indiscipline due to the failure to adhere to established operational weight limits.