Bell 47G-4A Collides with Power Lines Near Merseburg

Casualties unknown • Merseburg, DE

A private helicopter flight ended in a collision with high-voltage power lines near Merseburg, resulting in heavy damage to the aircraft and one injury.

What happened

On June 4, 2001, a Bell 47G-4A helicopter was conducting a private cross-country flight from Böhlen to Merseburg. Approximately 20 minutes after departure, the aircraft struck a three-phase, 20 kV high-voltage power line spanning the Saale River. The impact caused the three aluminum cables to sever and resulted in heavy damage to the helicopter, including a bent control rod and damage to the left fuel tank. The pilot managed to perform an emergency landing in a cornfield approximately 300 meters from the site of the collision. The pilot sustained one person with minor lacerations.

The investigation

The BFU investigation examined the wreckage and interviewed witnesses and the pilot. Physical evidence showed the initial contact occurred with a main rotor blade and the upper part of the cabin glazing. The investigation also noted that the power line masts, located on either side of the river, did not extend above the surrounding tree line.

The pilot stated that while attempting to climb to a higher altitude, he inadvertently increased the blade pitch so significantly that the rotor RPM dropped sharply. He claimed he initiated a steep descent and a right turn to stabilize the RPM, which led to the collision. However, investigators found the pilot's account of the maneuvers to be inconsistent with standard operating procedures. Eyewitnesses observed the helicopter in a hover over the river before it flew into the lines, with one witness estimating the aircraft was at an altitude of 50–60 meters.

Findings

  • The primary cause of the accident was that the pilot failed to detect the power lines in time while flying at a low altitude.
  • The power lines were difficult to identify because they were positioned against a dark, wooded background and the supporting masts were obscured by trees.
  • The pilot's claim of performing a steep descent to recover rotor RPM was deemed technically unsound, as the correct procedure would have been to reduce collective pitch and airspeed.
  • There was no meteorological reason for the low flight altitude.

Probable cause

The pilot flew at a low altitude beneath the tree line without a compelling reason and failed to identify the high-voltage power lines against the dark background of the forest.

Frequently asked questions

What happened in the 2001-06-04 Bell 47G-4A accident near Merseburg, DE?

A private helicopter flight ended in a collision with high-voltage power lines near Merseburg, resulting in heavy damage to the aircraft and one injury.

What aircraft was involved and where did it happen?

The accident on 2001-06-04 involved a Bell 47G-4A, at Merseburg, DE.

What was the probable cause of the accident?

The pilot flew at a low altitude beneath the tree line without a compelling reason and failed to identify the high-voltage power lines against the dark background of the forest.

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