Operators of the helicopter had been planning to replace the unit’s main rotor gearbox a week before it suffered a “catastrophic failure” off the Aberdeenshire coast.

However, the true fault within the gearbox was not detected and, according to the report, “The gearbox was declared serviceable by the operator and its planned replacement cancelled.”

As the Eurocopter AS332 L2 Super Puma began plunging towards the sea on April 1, 2009, the main rotor separated from the fuselage and the aircraft crashed.

The fourteen oil workers and two crew workers onboard died instantly.

The report by the Air Accidents Investigation Branch found that the helicopter had been maintained in accordance with regulations at the time, and cleared the flight crew of any blame.

However, lawyers for several victims’ families have suggested the possibility of criminal proceedings or a public inquiry.

Lisa Gregory, a partner at Aberdeen-based Balfour & Manson, said: “We will all take time now to consider the report while we wait to hear from the Scottish ministers, Crown Office and the police if there is to be a public inquiry, a fatal accident inquiry or any criminal proceedings.”

A spokesperson for Eurocopter told the Press Association: “The Eurocopter team was deeply saddened by this tragic event and our thoughts, deepest concerns and sympathy continue to be with the families, friends and loved ones affected by the accident.

“At Eurocopter, safety is and has always been the number one priority and the group continuously works to improve its safety standards, requiring suppliers to do the same and sharing this culture with customers. Eurocopter remains committed to working closely with the regulatory authorities, investigators and its operators to prevent the risk of accidents.”