A recent helicopter crash in the North Sea which has led to a number of oil majors suspending the use of Bond helicopter services pending an investigation into its safety and training record was caused by a gearbox failure, a report indicates.

British air accident investigators examining the crash believe that the gearbox failure led to the aircraft's main rotor breaking away, hitting and breaking the helicopter's tail boom.

An initial report from the Air Accidents Investigation Branch indicates that aside from the detachment of the tail boom, there was also a rupture in the right hand engine casing, although this is believed to be a secondary feature.

Full investigations into the accident are continuing so that the sequence of events can be completely understood.

A total of three new safety recommendations have been made following the crash. These include additional and enhanced inspections of the main rotor gearbox, and improvements to monitoring and warning systems on this type of helicopter.

The aircraft, which was operated by Bond Offshore Helicopters, crashed on April 1st 2009. Following the incident, a number of oil majors have indicated they will not use Bond's service until safety and training checks are carried out.

Oil and Gas Directory: Training and Development