Russia's largest helicopter operator, UTair, has grounded all of its Mil Mi-26T cargo helicopters following a crash on 20 December that killed one crew member.
"UTair Aviation has suspended all operations with Mi-26 helicopters in Russia and abroad until further notice," said the airline, which is the largest user of the type.
The accident occurred when an Mi-26, number RA-06121, with six crew on board, made a hard landing at a site in Russia's oil-rich Khanty-Mansiysk region in western Siberia. The aircraft landed about 30m from the designated landing area in an oilfield, rolled over and caught fire.
A crewman died at the scene, while others who were injured were taken to hospital in another UTair helicopter.
The airline said it is investigating the accident and is focusing on possible problems with the aircraft's tail booms. "Resumption of operations with Mi-26 helicopters will be determined for each helicopter individually on the basis of these inspections," UTair said.
Meanwhile UTair has taken delivery of three Eurocopter AS350 B3e-enhanced light single-engine helicopters.
In 2010 the operator ordered 20 of Eurocopter's light helicopter line-up - the largest contract of its kind in Russia. The first two aircraft - a twin engine AS355NP and an AS350 B3 - were handed over last year while the final helicopter will be delivered in 2013.
The aircraft will be used for oil and gas pipeline patrol, surveillance missions, VIP transportation and cargo airlift in Russia - including western and central Siberia.