Europe’s air safety regulator has issued an airworthiness directive for AW139 helicopters.
The European Aviation Safety Agency (EASA) ordered checks on AW139s which use a certain type of rotor component.
About 19 of the aircraft are operating on the UKCS, according to the most recent figures from Oil and Gas UK.
The watchdog said there had been reports of main rotor “slip rings” being found without the proper “lock wiring” or with “loose fasteners”.
It said the issue could lead to damage to the drive system and consequent “reduced control of the helicopter”.