US firm to make ‘minor’ alterations to back up power and altitude systems on Air NZ’s version of hi-tech aircraft

Air New Zealand's Dreamliner will need modifications to equipment including the "last line of defence" that provides back-up power in the remote event of a dual engine failure.

The plane, which arrived on Friday, was granted a safety waiver by the United States Federal Aviation Authority (FAA) to cover two systems that didn't comply with airworthiness regulations.

One issue relates to the Ram Air Turbine (RAT), a small windmill in the belly of the plane that is deployed to provide enough electrical power for flight controls if both engines fail.

Another problem has been identified with an altitude selector.

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Air NZ's new Dreamliner arrives:

Air New Zealand's long anticipated Dreamliner has touched down at Auckland Airport. Four years later than originally hoped, the plane landed around its scheduled arrival time. Around 45 Air New Zealand staff greeted the plane at the airline's engineering base.

This country's safety body, the Civil Aviation Authority, said it was satisfied with the FAA decision.

Boeing's vice-president of development for the 787 programme, Mark Jenks, was on the 14-hour delivery flight and said the fixes were minor.

"We have plans to close those out, they're fairly minor issues and we have plans in place and there's no concern there," he told the Business Herald.

It is reasonably common for new aircraft, especially the first of a new model, to require some modifications by the supplier after delivery.

Air New Zealand said both issues were publicly notified as part of the flight manual approval process by the FAA. Neither has a material effect on safety and the problem would be fixed next year.

Inside Air NZ's Dreamliner

2013 had Air New Zealand's first Dreamliner flying into Auckland. NZ Herald travelled to Seattle to preview the plane and attend the Dreamliner opening. Video / Alan Gibson / Boeing

"With respect to the Ram Air Turbine the likelihood of an occurrence that would affect the safety of flight is considered extremely improbable by the FAA and therefore acceptable from a certification perspective," a spokeswoman said.

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Aviation Week reported Boeing 787 chief project engineer and vice-president Bob Whittington as saying that the probability of the RAT being used before the fix was in the region of one in a trillion.

"You have to lose six generators before you need the RAT," Whittington said.

The capacitor in the turbine found to be at fault showed evidence of degrading only after being used several times during flight testing - a circumstance that an in-service aircraft would never experience, Aviation Week reported.

The altitude-select dial in the cockpit will also be fixed on planes now being delivered. Flight crew set the altitude by pressing and then rotating the dial which was found to lack sufficient torque resistance so could be wrongly set.

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The Air New Zealand spokeswoman said the altitude selector issue was mitigated by adhering to an operational manual procedure for the pilot to visually check the setting whenever the dial is touched.