The Royal New Zealand Air Force (RNZAF) has eased flying restrictions on its fleet of eight NH90s, three weeks after an engine failure resulted in one of the medium utility helicopters making an emergency landing.

An NH90 had just departed RNZAF Base Woodbourne with nine people on board en route back to its base at Ohakea when the crew felt a large vibration followed by a loss of power in the helicopter’s right-hand Rolls-Royce Turbomeca RTM 322-01/9 engine. The crew safely performed an immediate precautionary landing on a nearby private airstrip.

On April 20, the RNZAF elected to restrict NH90 flying operations, preventing them from flying at night, over water and over mountainous terrain, while the problem engine was removed in situ and initially shipped to Safran Helicopter Engines at Sydney’s Bankstown Airport for a detailed inspection.

“The limitation on NH90 operations will prevent flights where an immediate landing will not be possible in the case of an engine-related emergency. For example, over built-up areas, mountainous terrain or over water,” read an NZDF statement following the incident.

Those restrictions were then largely lifted on May 8.

“We know now how the aircraft performed with one engine and we are working with the aircraft engine manufacturer to clarify the initial causes of the engine failure,” Chief of Air Force Air Vice-Marshal Tony Davies said.

“Those investigations have given us confidence the aircraft can be operated safely following a similar engine failure. Therefore we have returned to normal flying operations, except where the aircraft is operating at its upper weight limits, and plan to return to full operations as soon as the engine manufacturer has determined the reasons for the initial failure.”

During the period of restricted operations, the NH90s continued to fly on training missions around their home base of RNZAF Base Ohakea and were available for “urgent tasks of national significance”.