The Australian Defence Force’s (ADF) MRH90 multirole helicopters will restart flying operations next week following a detailed inspection on their engines.

A fleet of 11 MRH-90 transport helicopters was grounded by the ADF in April following instances of engine trouble.

The Defence Materiel Organisation helicopter systems division head Rear Admiral Mark Campbell said reports alleging pilot error being a factor in the engine failure were incorrect.

“Flying operations will begin shortly following approval by the Operational Airworthiness Authority,” he said.

“Extensive work has been conducted by Rolls-Royce Turbomeca and our industry partners with support from The Defence Science and Technology Organisation to identify the cause of the engine failure.

“We are advised that the failure resulted from compressor blade fracture due to contact with the engine casing.”

Technical issues associated with the engine malfunction will delay the first army deployment of MRH90 troops and the first flight at sea for the Australian Navy until mid-2011.

ADF ordered a total of 46 MRH90 helicopters for the Australian Army and Navy, of which 11 are undergoing flight tests and are expected to achieve operational readiness over the next few years.