Rebooting computers will overcome glitch that could cut all power.

Air New Zealand and other airlines will shut down Dreamliners completely every three months after tests by Boeing exposed a problem that could cause the plane to lose all electrical power and a loss of control.

The United States Federal Aviation Administration (FAA) said laboratory tests had exposed a computer glitch in a 787 that was run continuously for 248 days and could cause it to lose power as generator units simultaneously went into failsafe mode.

The administration said this could happen at any phase of flight in a plane that relies extensively on electricity from its own generators rather than using pneumatics to power hydraulics and other equipment.

Reports from the United States say that according to Boeing's records, all jets in service have been powered off and turned back on as part of routine maintenance, so there is no immediate danger of a plane in service losing power.


The FAA directive requires operators of the plane to periodically shut off power completely to planes during maintenance while Boeing develops software to fix the problem. The administration has taken more drastic action in the past over even greater concerns about safety when it grounded the Dreamliner fleet in 2013 because of the risk of battery fires.

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China Southern Airlines, Chile's LAN and Air New Zealand operate 787s out of Auckland. The New Zealand airline has three of the planes in its fleet and nine more on order.

It said the FAA order required it to undertake a "power cycle" every three months.

"Air New Zealand fully complies with all airworthiness directives from relevant aviation authorities and this requirement will be incorporated into our ongoing maintenance plans," a spokeswoman said.

The FAA has direct control over United States-registered planes but in practice its rulings apply to aviation operators around the world.

The Civil Aviation Authority monitors operators here and a spokesman said Air New Zealand was required to incorporate the directive into its maintenance schedule.

The FAA says the deactivation takes about an hour and costs about NZ$110. It said the risk to the flying public justified waiving a feedback period and issuing the safety notice immediately.


"An unsafe condition exists that requires the immediate adoption of this AD [airworthiness directive]."

Nearly 270 Dreamliners have been delivered around the world and have flown an estimated 44 million people.

The planes are largely made of carbon composite, and light-weight, efficient engines and aerodynamic features help make fuel savings of up to 20 per cent compared to similar aircraft. The Dreamliner first entered service in 2011 after four years of design and production delays but since the battery fire issue in 2013, there have been few reports of reliability issues.

The jets have a list price of US$218 million to US$260 million ($289-345 million) depending on the model, although airlines typically get big discounts depending on the number of aircraft they are buying.