New Delhi (PTI): A preliminary probe into the helicopter crash that killed six people in Uttarakhand in May has found that the main rotor blade of the chopper struck an overhead fibre cable, before tumbling down the hillside and coming to rest against a tree.

The Aircraft Accident Investigation Bureau (AAIB) said on Saturday that the investigation team is working on the further course of action to find the root cause of the accident.

The 17-year-old Bell 407 helicopter operated by Aerotrans Services Pvt Ltd, with six passengers onboard, crashed 24 minutes after being airborne on May 8.

The pilot and five passengers died in the accident, while one passenger sustained serious injuries.

AAIB said that the helicopter, which was airborne from Kharsali helipad at 8.11 am on May 8, was destroyed in the crash but there was no fire. The accident happened at Gangnani in Uttarkashi at 8.35 am.

In its five-page report, AAIB said the helicopter flew for 20 minutes before descending from its assigned altitude.

"Initially, the pilot attempted to land on the Uttarkashi-“Gangotri Road (NH 34) near Gangnani in Uttarkashi. During the landing attempt, the helicopter's main rotor blade struck an overhead fibre cable running parallel to the road.

"It also damaged some roadside metallic barricades. However, the helicopter was unable to land and tumbled down the hillside. Eventually, it came to rest against a tree, approximately 250 feet deep in a gorge," it said.

The helicopter, powered by Rolls Royce engine, was manufactured in 2008.

The US National Transportation Safety Board and Canada's Transportation Safety Board have appointed accredited representatives and technical advisors for the investigation.

"The investigation team is coordinating with them for further course of action required to find out the root cause(s)," the report said.