What happened
On November 2, 2007, a private Eurocopter EC120 B, registration EC-HQS, was performing a visual flight mission from Madrid-Cuatro Vientos to a private estate near El Espinar, Segovia. After completing the initial leg of the flight, the aircraft prepared for the return journey.
During the takeoff from the estate, the helicopter began to ascend. Shortly after lifting off, the aircraft tilted sharply to the right. The main rotor blades struck the ground, causing the helicopter to rotate approximately 100 degrees counter-clockwise while sliding across the terrain. The aircraft eventually came to rest on its right side. The pilot and one passenger were able to exit the aircraft on their own, and both remained uninjured. The aircraft sustained significant damage.
The investigation
Investigators examined the wreckage and the takeoff site, which consisted of irregular ground with short grass. The aircraft had been positioned on a small, slightly sloped platform. Evidence of the main rotor blade impact was found dispersed across the terrain.
Technical inspections of the Eurocopter EC120 B revealed extensive damage to the main rotor system, including broken blades near the root and a destroyed rotor head. Investigators also noted that the hydraulic fluid reservoir was empty and discovered a longitudinal fracture in one of the three servocontrols (the actuator responsible for pitch and roll control).
A specialized laboratory analysis of this servocontrol determined that the 80 mm fracture was caused by an internal overpressure resulting from an external load, rather than an internal mechanical failure. Furthermore, data retrieved from the Vehicle and Engine Management Display (VEMD) showed no engine or system malfunctions prior to the accident.
Findings
- The investigation established that the damage to the servocontrol occurred as a result of the impact with the ground, which transmitted energy back into the control mechanism.
- The pilot and witnesses described a very rapid sequence of events, with the aircraft tilting almost immediately after liftoff.
- The primary cause of the accident was a loss of control during takeoff, which led to a dynamic rollover.