What happened
On January 13, 2005, at approximately 11:30 UTC, a Bell 212 helicopter, registration CS-HFJ, was conducting a rescue training mission near Salir, Loulé. The flight, operated by Helisul, involved two pilots, a winch operator, and two rescue technicians acting as both rescuers and victims during the exercise.
During the final phase of a recovery maneuver in a wooded mountainous area, the two technicians were being hoisted approximately 20 meters above the ground and 2 meters below the aircraft's skids. Without warning, the winch cable snapped with an audible pop. The two men fell into a ravine. One rescue technician was killed, and the other sustained critical, multi-trauma injuries. The crew of the aircraft remained uninjured, and the aircraft sustained no damage.
The investigation
The GPIAAF investigation focused on the physical condition of the recovery equipment and the aircraft's components. Investigators examined the broken section of the Lucas Western winch cable and the aircraft's right-side skid.
Testing revealed that a stainless steel protective plate had been installed on the right skid to protect it from wear. This plate was not authorized or certified by the Aeronautical Authority. The investigation found that the front edge of this plate had become partially detached, creating a "scissor effect" where the cable could pass between the plate and the skid.
Laboratory analysis of the cable confirmed that the surface had suffered significant erosion and deep indentations caused by continuous friction against the uncertified plate. These defects were not detectable through visual inspection or tactile checks while wearing standard work gloves. Ultimately, the cable's structural integrity was compromised, leading to a ductile fracture at a tension level well below its rated capacity.
Findings
- The primary cause of the accident was the rupture of the winch cable due to severe erosion and deep indentations caused by friction against an uncertified skid protection plate.
- The installation of the uncertified stainless steel plate contributed to the accident.
- The small dimension of the winch arm prevented sufficient clearance between the cable's operating plane and the helicopter skid.
- The damage to the cable was undetectable during routine pre-flight inspections using standard manual methods.