What happened
On March 21, 2008, at approximately 15:05 local time, a Robinson R22 helicopter, registration EC-JCP, was conducting a private local flight near Miraflores de la Sierra, Madrid. The flight was being conducted under the supervision of an instructor to fulfill required hours for a commercial pilot training course. The aircraft had departed from Madrid Cuatro Vientos Airport earlier that afternoon.
While flying alongside the Arroyo del Valle viaduct—a structure supporting the Madrid-Valladolid high-speed rail line—the helicopter's front right cabin area struck a 0.5 mm diameter steel cable. This cable was suspended from the underside of the viaduct. The impact caused the helicopter to lose control and crash to the ground near the central span of the viaduct.
Both crew members were wearing seatbelts, which functioned as intended. The pilot sustained a facial injury caused by an unanchored GPS receiver striking them, while the instructor suffered a heavy blow to the back. Both occupants were able to exit the aircraft and eventually sought medical assistance at a local health center.
The investigation
Investigators examined the wreckage and the site of the impact. The investigation recovered approximately 43 meters of the 0.5 mm steel cable, which was found partially wrapped around the main rotor drive shaft housing and the tail rotor. The investigation also noted that the tail rotor blades had broken near their attachment points and were found separated from the main wreckage.
Technical analysis of the components revealed that the tail rotor drive shaft had suffered a torsional fracture, consistent with an instantaneous braking force. Furthermore, the tail cone exhibited a bending fracture, which was consistent with the sudden deceleration experienced when the aircraft impacted the ground while the main rotor was still producing power.
Findings
- The accident was caused by the contact between the helicopter and a suspended steel cable hanging from the railway viaduct.
- The cable was part of a load-testing sensor system used during the viaduct's construction, connected to a seismograph on the ground to monitor vibrations.
- The impact with the cable led to the loss of the tail rotor and subsequent loss of aircraft control.
- The aircraft sustained significant damage, including the separation of the tail cone and the destruction of the tail rotor blades.