FRANKFURT European safety regulators said they had lifted a ban on commercial flights of helicopters similar to a Super Puma that crashed in April after manufacturer Airbus Helicopters (AIR.PA) contained a potential weakness inside the gearbox.
The European Safety Aviation Agency said in a bulletin that one of two configurations of planet gear inside the helicopter's main gearbox had "higher operating stress levels" and that only a more reliable, lower-stress configuration would now be used.
Combined with other controls, the new practice means "an acceptable level of safety can be restored," EASA said.
However, it was not yet known whether the stress levels were directly related to the crash that killed 13 people in April.
EASA grounded two models of Super Puma, the H225 LP and AS332 L2, in June following the discovery of metal fatigue in the gearbox of the helicopter which crashed in Norway.
Airbus Helicopters said on Friday it took note of EASA's decision to lift the suspension and would help customers return the aircraft to service "at the appropriate time". Following the crash, UK and Norway imposed separate restrictions on flights.
(Reporting by Maria Sheahan, Tim Hepher; Editing by Alexander Smith)