What happened
On June 11, 2021, an Airbus Helicopters AS 350B3 was performing supply flights to mountain huts in the Oberstdorf region. At approximately 13:35 local time, the pilot landed the helicopter on a level plateau on a service road between Bolgenalpe and Zunkleiten Alpe.
Two ground workers had previously secured the landing site and cordoned off the access road. After landing, the flight crew began unloading the aircraft. During the engine shutdown phase, while the engine was still running to cool down, one of the ground workers moved toward the rear of the aircraft and came into contact with the rotating tail rotor.
Upon seeing the incident, a flight crew member immediately instructed the pilot to shut down the engine and call for emergency services. The pilot executed the shutdown, applied the rotor brake, and contacted emergency medical services. The ground worker, who was wearing a protective helmet, sustained severe head injuries from the impact. The tail rotor sustained minor damage.
The investigation
The BFU investigation established that the incident occurred while the engine was in its cooling phase. The investigation noted that a stone was located on the ground directly beneath the tail rotor, and the clearance between the lowest point of the tail rotor blade and the ground was approximately 111 cm.
Physical evidence at the scene included bent ground-strike indicator plates on both tail rotor blades, as well as traces of the worker's red helmet and hair caught on the blade tips. The worker's protective helmet sustained significant damage, with a large breakage on the left side near the ear protection area.
Findings
- The primary cause of the injury was the contact between the rotating tail rotor and the ground worker's head.
- The ground worker was wearing a certified protective helmet, which helped mitigate the severity of the injury.
- The second ground worker was not aware of the movement toward the tail rotor as they had turned away to attend to cargo in a trailer.
- While the aircraft operator held a specialized operations authorization for high-risk flights, the incident occurred during routine ground operations following a landing.