Witness Tells Investigators Main Rotor Severed Cabin

A helicopter involved in a 2005 fatal accident in Perth, Scotland was cut in two by its own rotor blades, investigators informed a fatal accident inquiry board at the Perth Sheriff Court Tuesday.

The Bell 206B Jet Ranger II (type shown above) was flying from Cumbernauld to Aberdeen on December 21, 2005 on a gas pipeline inspection run for the National Grid when it crashed near Coupar Angus, killing the pilot and observer.

A catastrophic failure in the rear of the aircraft that tore the stabilizer fin, rear rotor blade and gear box from their mountings is said to be at fault, according to the Dundee Courier.

Witnesses reported seeing the helicopter "fall apart" in mid-air before nose-diving to the ground, killing pilot Robert Philip Ward, 48, of Glasgow, and observer Edward Lapsley, 56, of Tyne and Wear.

The helo was scheduled for a routine maintenance inspection when they were through with the job.

According to the BBC, witness Andrew Brown told the inquiry, "Suddenly bits started flying off it. The tail broke up first. The rotor from the tail was breaking and the whole tail came off. That seemed to break first and get entangled with the main rotor. It started dropping straight away. It just went straight down."

The Air Accidents Investigations Branch, which is responsible for the investigation of civil aircraft accidents in the UK, concluded the crash had ultimately been caused by metal fatigue.

AAIB inspector Keith Conradie said the investigation quickly focused on the helicopter's tail.

"The first items in the wreckage trail were items associated with the rear part of the helicopter. Found first in the accident location were the vertical fin and the stinger, which hangs underneath the vertical fin," he said.

"The vertical fin came away, swinging underneath and into the area of the tail rotor," he continued. "This caused the tail rotor and gear box to depart from the helicopter."

He said the loss of the tail rotor and the loss of mass would have made the aircraft "impossible to control, as it would have become "nose heavy" and would have quickly started to dive.

"It appears that the main rotor-blades flexed and struck the tail boom as the pilot attempted to lift the helicopter out of the nose dive," Conradie said. "They then flexed again, striking the cabin. The front of the cabin was cut off."

FMI: www.aaib.dft.gov.uk/home/index.cfm