HELICOPTER manufacturer Sikorsky has grounded all its S92s for safety inspections following an incident in which a chopper lost control during an emergency landing offshore at the end of December.
Inspections of the tail rotors of all 60 S92 helicopters operating in the North Sea are now being carried out.
The maintenance programme is expected to take several days to complete - leading to widespread disruptions in offshore traffic.
In Shetland, both Sumburgh and Scatsta airports are affected. The Shetland Coastguard helicopter, based at Sumburgh, is also grounded.
Les Linklater, executive director of Step Change in Safety, said: "This morning (Tuesday) Sikorsky released an Alert Service Bulletin (ASB 92-64-001) for the S92 requiring a onetime visual inspection of the tail rotor pitch change shaft and bearing assembly on the world wide S92 fleet prior to the next flight.
"The decision made by Sikorsky is a precautionary measure to ensure continued safe flight operations and we are aware that helicopter operators are working to assess the impact of this requirement, while investigating all opportunities to limit the effects on the flying program.
"Currently the duration of the inspections is expected to take up to 11 man hours, which means this will cause some short term delays.
"We are in close communication with trades unions, helicopter operators and the Civil Aviation Authority."
On 28 December, a S92 helicopter responded unexpectantly as it attempted to touch down on the West Franklin platform. Its wheels gauged the helipad. Reportedly damaging the undercarriage of the chopper. No one was injured.