What happened
On 23 May 2022, an Aerospatiale AS3COB3e helicopter, registration F-HCHB, was engaged in firefighting operations to combat a forest fire in the municipality of Świerklaniec. The aircraft was utilizing an underslung bambi bucket to collect water from Rogoźnik Lake.
After completing eight successful water drops, the helicopter attempted to refill the bucket at approximately 15:00 hrs. During the lifting process from the lake, the aircraft began an uncontrolled rotation to the right, spinning approximately 270 degrees. The pilot attempted to stabilize the aircraft by reducing the general pitch, which resulted in a ditching maneuver. During the impact, the rotor blades struck the water surface, causing the helicopter to tilt sharply to the left and sink to a depth of approximately 2.5 meters.
The pilot sustained minor injuries but was able to evacuate the sinking wreckage on his own after releasing the right-hand door. The aircraft was destroyed, with the impact causing the main rotor hub, blades, and gearbox to detach from the airframe.
The investigation
The PKBWL investigation examined the flight history, aircraft maintenance records, and engine performance data. Investigators analyzed the wreckage, which was recovered from the lake three days after the accident. The investigation also reviewed the pilot's physiological state and the operational environment, including the lack of ground-based task specialists to assist with positioning during the water refilling process. Data retrieved from the engine data recorder (EDR) confirmed that the collision with the water occurred under high torque conditions.
Findings
- The helicopter was properly maintained, with a valid certificate of airworthiness and within prescribed weight and balance limits.
- The pilot was properly licensed and medically certified for the operation.
- The pilot was performing high-intensity firefighting operations and was experiencing fatigue following several previous flights that day.
- The pilot was likely operating under pressure to complete the mission quickly.
- The water collection was performed in a hover without the assistance of ground-based task specialists to provide visual signals.
- The helicopter's tail rotor came into contact with the lake surface, likely due to temporary inattention or a delayed reaction to the aircraft drifting.
- The heavy underslung water container and the surface swell caused by rotor downwash made maintaining a precise hover more difficult.