What happened
On 2 July 2012, a Sokol PZL SWIDNIK W-3A, registration EC-JUN, operated by INAER, was engaged in firefighting operations near Yátova, Valencia. The crew, part of the Forest Fire Reinforcement Brigade (BRIF), was attempting to land atop a mound to unload a bambi bucket for water drops. During a circling maneuver over two hills, the helicopter experienced a partial loss of power. The crew attempted an emergency landing in an adjacent area, but the aircraft impacted the ground. Both crew members sustained serious injuries.
The investigation
The CIAIAC investigation focused on the mechanical failure of the engine and the crew's response to the emergency. Investigators examined the wreckage and performed laboratory inspections on the broken turbine shaft of engine 1. The investigation also reviewed the operator's training programs, maintenance records, and the adequacy of the aircraft's onboard documentation. The inquiry established that while the maintenance of the aircraft was up to date, the crew's handling of the emergency did not align with the procedures outlined in the aircraft's Flight Manual.
Findings
- The primary cause of the power loss was the fatigue failure of the flexible coupling between the turbine output and the intermediate shafts in engine 1.
- The subsequent shutdown of engine 1 was triggered by the aircraft's design overspeed protection system.
- The crew failed to follow established emergency procedures, including the failure to press the 2.5 min-OEI button, which was required for a Category A landing.
- There was a significant lack of coordination and teamwork between the two pilots, with communication being nearly non-existent during the critical phases of the flight.
- The aircraft lacked adequate onboard checklists, forcing the crew to rely on memory during the emergency.
- The operator's manual lacked specific details regarding the conduct of supervised flights and the qualifications required for supervising pilots.
- Neither pilot had received Multi-Crew Cooperation (MCC) training.