Two Super Puma helicopters were at the centre of fresh safety fears yesterday.
The Bond aircraft, which were travelling independently to different offshore installations, were both forced to return to the heliport in Aberdeen following concerns.
It is understood passengers onboard the flights believed they heard unusual noises coming from the helicopters and alerted the pilots who chose to return to base.
However, it was soon discovered there were no problems with either aircraft.
Both helicopters were Super Puma L2s manufactured by Eurocopter. The EC225 model of the Super Puma has been grounded since October following the second ditching in the North Sea this year.
Bond Helicopters, which owns the aircraft involved in yesterday’s incidents, said both machines had been checked and were found to have no problems. They have since returned to service.
A spokesman said: “Two flights this morning were returned to base. They went in for immediate inspection.
“Both helicopters are L2s, the only version of the Super Puma that Bond is flying at the moment. One was heading for the Miller platform and the other was heading for the Borgholm Dolphin drilling rig.”
Eurocopter believes the incident involving a CHC-owned EC225 last month was almost identical to one involving a Bond helicopter in May.
Last night they issued a new report which indicated they were closer to understanding the root cause of the faults – but said it would still be February before the aircraft was likely to fly again.
An initial bulletin from the Air Accident Investigation Branch reported that a crack in the main gear shaft had been discovered after the helicopter carried out a controlled ditching off Shetland.
A warning light indicated a failure of the main gearbox lubrication system and triggered the crew’s response.
Eurocopter believes the warning light was set off in error – as happened with the ditching of the Bond helicopter in May.
In both incidents all passengers and crew managed to escape into liferafts before being picked up.