What happened
On December 19, 2013, an HB-350B helicopter, registration PT-HLU, was conducting a local training flight near Belo Horizonte, Brazil. The flight, operated by Escola de Pilotagem Ltda. (EFAI), involved two pilots and one passenger. During an autorotation training maneuver at Aeródromo Carlos Prates, the aircraft experienced a sudden and heavy landing characterized by a high rate of descent and low main rotor RPM.
The impact with the ground caused the main rotor blades to flex downward, striking the upper portion of the tail boom. The collision resulted in substantial damage to the main rotor blades, tail boom, tail rotor drive shaft, and landing skids. Despite the significant structural damage to the aircraft, all three occupants emerged uninjured.
The investigation
CENIPA's investigation focused on the execution of the autorotation maneuver and the crew's performance. Investigators examined the aircraft's maintenance records, which showed the helicopter was within weight and balance limits and had a valid airworthiness certificate. Meteorological conditions at the time of the accident were favorable, with good visibility and calm winds.
The investigation analyzed the flight dynamics during the final stages of the maneuver. Evidence indicated that the aircraft was operating with low rotor RPM at the moment of touchdown. The investigation also reviewed the flight crew's experience, noting that both pilots were qualified and experienced in the aircraft type. No mechanical or technical failures were identified as contributing to the event.
Findings
- Inadequate control inputs: The pilot flying failed to maintain the required rotor RPM and airspeed, leading to a high-energy impact with the ground.
- Delayed instructor intervention: The pilot in command (PIC) failed to intervene promptly to correct the student pilot's operational errors or to abort the maneuver when parameters deviated from the flight manual.
- Poor situational awareness: The PIC demonstrated inadequate judgment and a possible passive attitude, which may have led to a delayed perception of the developing risks during the training exercise.