The ASB comes as a result of Sikorsky’s investigation into the West Franklin helicopter incident, where a S92 helicopter spun on the helideck upon landing – damaging the platform and the aircraft.

Aircraft operators immediately grounded all flights to enable the technical checks to be conducted, leaving the North Sea with only a handful of helicopters based in Aberdeen able to fly.

The technical checks are expected to take 11 hours for each aircraft and with dozens of S92s and a limited amount of engineers, the requirements will see the majority of S92’s out of service for the coming days. It could take over a week before all S92s return to active service.

According to Flight Radar 24, Bristows has 21 S92 aircraft operating in the UK, CHC has 19 and Babcock have 11.

Aberden operator NHV is operating as normal however, flying a fleet of Airbus H175’s out of Aberdeen and being unaffected by the S92 grounding.

With S92 operators having other helicopter variants based around the UK, operational decisions are being made as to whether to utilise alternative aircraft in the short term.

Hopes for offshore workers looking to return home this week are fading as even with replacement helicopters, 2 days of severe weather are likely to further impact any replacement aircrafts operations.

A spokesperson for Sikorsky said:

“Safety is our top priority, and Sikorsky is working closely with our customer and investigative authorities to determine the root cause of the loss of tail rotor authority in the Dec. 28 installation landing.  

Although the investigation into the Dec. 28 incident has not been completed, Sikorsky released an Alert Service Bulletin on Jan. 10 to define additional interim inspection requirements for the S-92 Tail Rotor Pitch Change Shaft.

Those procedures include an off-aircraft check of the PCS bearing and that check must be done before next flight with some leeway for getting back to base. We are committed to keeping our customers informed. We will further communicate findings if the investigation reveals any safety or airworthiness issues that affect the S-92 helicopter fleet.”

Les Linklater Executive Director of Step Change in Safety, and head of the Offshore Helicopter Safety Leadership Group representing North Sea Operators gave the following statement:

“This morning 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. Furthermore, the Offshore Helicopter Safety Leadership group has convened a call to discuss what is being done to maintain safe flight operations and limit the operational impact and inconvenience this has caused, and will provide an update when it is available.”