Robinson R44 strikes power lines during simulated emergency landing

Casualties unknown • nahe Blankenheim-Esch, DE

A training flight involving a Robinson R44 Raven I ended in an accident near Blankenheim-Esch when the aircraft struck overhead power lines during an autorotation maneuver.

What happened

On April 9, 2008, at approximately 10:30 local time, a Robinson R44 Raven I helicopter was conducting a training flight from Bonn-Hangelar to Dahlemer Binz. The flight, which lasted about 55 minutes, was intended for navigation and flight maneuvers. As the crew approached the destination, the flight instructor initiated a simulated emergency landing procedure, known as an autorotation.

The instructor selected a meadow situated between two small wooded areas as a suitable landing site and began the autorotative descent toward the southwest. During the descent, the crew noted a pasture fence crossing the field and attempted to clear it at a sufficient altitude. However, the instructor did not observe the electricity pylons located behind the woods on either side of the meadow. During the flare maneuver, the crew noticed a 20-kV power line running across their path. Despite an attempt to pull the helicopter above the wires, the aircraft struck the line, severing all three aluminum cables. The helicopter subsequently impacted the ground with a leftward roll.

The investigation

The BFU investigation focused on the sequence of events leading to the impact and the condition of the aircraft. The investigation established that the accident occurred at an elevation of approximately 1,80 and MSL, north of Esche and Alendorf. The wreckage showed significant damage, including a broken left skid, bent main rotor blades, and a severed tail boom. The tail rotor gearbox and vertical stabilizer were torn from the aircraft and found lying to the north of the main wreckage, with one power cable wrapped around the gearbox.

Investigators examined the aircraft for mechanical failures but found no evidence of technical malfunction. The investigation also noted that the aircraft was not equipped with a flight data recorder or cockpit voice recorder, as these were not required for this type of operation.

Findings

  • The primary cause of the accident was the impact with the 20-kV power lines during the flare maneuver.
  • The crew failed to identify the electricity pylons positioned behind the wooded areas prior to the descent.
  • The power lines were only detected during the final stage of the landing maneuver, leaving insufficient time to avoid the obstacle.
  • The aircraft sustained extensive structural damage, including the loss of the tail section and damage to the fuel system, though no fire occurred.

Probable cause

The accident was caused by the helicopter striking overhead power lines during an autorotation maneuver, primarily because the electricity pylons were not identified during the approach to the selected landing site.

Frequently asked questions

What happened in the 2008-04-09 Robinson Helicopter Company / accident near nahe Blankenheim-Esch, DE?

A training flight involving a Robinson R44 Raven I ended in an accident near Blankenheim-Esch when the aircraft struck overhead power lines during an autorotation maneuver.

What aircraft was involved and where did it happen?

The accident on 2008-04-09 involved a Robinson Helicopter Company /, at nahe Blankenheim-Esch, DE.

What was the probable cause of the accident?

The accident was caused by the helicopter striking overhead power lines during an autorotation maneuver, primarily because the electricity pylons were not identified during the approach to the selected landing site.

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