It had been reported by a TV news channel that the aircraft had its maintenance servicing delayed twice.

But the NCAA insisted servicing was carried out in accordance with its standard operating procedures.

The NCAA said these parts must be considered for replacement after 2,000 hours flying time, although it was common for operators to apply for extensions to this for “operational reasons”.

NCAA senior legal adviser, Hege Aalstad, said “CHC applied for and received two 100-hour extensions to enable the gearbox to be replaced.

“The gearbox was replaced on January 17 this year within the correct timeframe. It was not overdue.”

Mr Aalstad said the aircraft’s rotor head had also been replaced, within the correct operational time frame, on March 27 2016.

The EC225 involved in the Turoey disaster underwent a supervised service audit by the NCAA between September 15-18 last year at CHC Helicopter’s Bergen facility.

The NCAA said the audit had not revealed anything unusual or picked up any discrepancies.

A Norwegian Civil Aviation Authority official confirmed to local media that the helicopter involved had maintenance servicing delayed twice in 2015.

Hege Aalstad, a senior legal adviser at the authority, said: “I can confirm that this specific helicopter had seen its maintenance delayed. It is correct that there was an application for a so-called travel-time extension.

“The first one was for a delay of 100 flying hours … and the other was also for 100 flying hours.”

The crash marked the first helicopter crash in the Norwegian sector of the North Sea in almost two decades.

Seven years ago this month a similar helicopter, operated by Bond, suffered a catastrophic failure of its gearbox as it flew back to Aberdeen from a North sea platform, killing all 16 on board.

It was one of five serious incidents involving Super Puma aircraft in as many years in the UK sector, claiming a total of 20 lives.