Report on a serious incident near the mobile platform Linus, 10 NM west of Ekofisk L, North Sea on 5 June 2023 with Sikorsky Aircraft S-92A, LN-OMI, operated by Bristow Norway AS
Aviation report 2025/11
A Sikorsky S-92A helicopter had an uncommanded engine shutdown shortly after take-off from the Linus platform near the Ekofisk field in the North Sea.
LN-OMI had picked up passengers from the mobile platform Linus. Shortly after takeoff, the crew heard a loud noise and received a warning in the cockpit that the left engine had stopped.
The crew followed checklists and flew on one engine to Stavanger Airport Sola where it landed without problems.
The investigation has revealed that the engine, a General Electric CT7-8, stopped because the joint between the compressor rotor's centrifugal compressor and the rear axle had come loose after twelve T-bolts had ruptured. The reason the bolts ruptured is likely maintenance-related in connection with a major repair.
During the investigation, the repair shop has taken several measures to prevent a recurrence.
The NSIA is issuing a safety recommendation to the engine manufacturer General Electric to update their shop manual to identify possible human errors when performing critical tasks.
Published 26.11.2025
Safety recommendation
Safety Recommendation Aviation nr. 2025/06T
On 5 June 2023, LN-OMI, a Sikorsky S-92 helicopter, experienced an uncontrolled engine shutdown while transporting 14 passengers from the Linus mobile platform in the North Sea to Stavanger Airport Sola. The cause of the engine shutdown was that the twelve T-bolts connecting the centrifugal compressor to the compressor rotor rear shaft had fractured after a period of fatigue.
The engine manufacturer General Electric has published a Shop Manual GEK105175 applicable for the CT7-8 engine that describes the joining of the centrifugal compressor and the compressor rotor rear shaft. The task is critical and complex with several different work steps. The complexity of the task increases the risk of human error.
The Norwegian Safety Investigation Authority recommends that General Electric update the Shop Manual GEK 105175 to include a safety measurement to identify possible human errors after the assembly and balancing of the compressor rotor has been completed.
Facts
| Location | Linus platform, North Sea, offshore |
| Occurrence date | 05.06.2023 |
| Aircraft | Sikorsky øvrige |
| Operator | Bristow Norway AS |
| Registration | LN-OMI |
| Meteorological conditions | IMC |
| County | Rogaland |
| Type of occurrence | Incident |
| Type of operation | Offshore |
| Category of operation | Heavy, helicopter (> 2 250kg) |
| Aircraft category | Helicopter, Multi-engine, Turboprop/turboshaft |
| FIR/AOR | ENSV (Stavanger ATCC) |