Report: Worn clutch led to loss of oil pressure
It was a completely worn out coupling to an oil pump that caused a helicopter to experience a sudden loss of oil pressure in the main gearbox during an exercise in the North Sea on 25 September last year. The National Accident Investigation Board concludes this in a recent report (external link).
The Sikorsky S-92A helicopter was operated by Bristow. On 25 September 2021, it finished training on a rescue mission and was due to return to the Ekofisk field in the North Sea, specifically Ekofisk Lima. The helicopter experienced a sudden loss of oil pressure in the main gearbox.
The crew immediately headed for Ekofisk Lima for landing. It took place without any problems and no one was injured.
The investigation has shown that the loss of oil pressure came as a result of the coupling that operated one of the oil pumps being completely worn out. The Accident Investigation Board believes that the abnormal wear was the result of several factors.
After the incident, Sikorsky has adjusted down the running time of the link so that something similar does not happen again. In practice, this means that the helicopters must come in for service more often.