The US Federal Aviation Administration (FAA) has approved Boeing's improved 787 Dreamliner battery design, clearing the way for the twinjet to return to commercial service more than three months after it was grounded.

The agency says today it will issue instructions next week to 787 operators for installing the modified battery design on their aircraft. It will publish in the Federal Register the final directive to allow the twinjet to return to service, which will take effect upon publication.

"The FAA will require airlines that operate the 787 to install containment and venting systems for the main and auxiliary system batteries, and to replace the batteries and their chargers with modified components," it says.

FAA administrator Michael Huerta says a team of certification specialists from the agency "observed rigorous tests" by Boeing and "devoted weeks to reviewing analysis of the design changes to reach this decision".

The agency will closely monitor modifications to 787s in the US in-service fleet, it says. "The FAA will stage teams of inspectors at the modification locations. Any return to service of the modified 787 will only take place after the FAA accepts the work," says the FAA.

It will also support other authorities in other countries as they finalise their own procedures to return the aircraft to commercial service.

The FAA grounded the 787 on 16 January, following two incidents involving the lithium-ion batteries powering the aircraft's auxiliary power unit on two different 787s. The FAA's decision prompted a global grounding of the aircraft type across all operators.

Boeing's improved battery design involves three new layers of over-lapping protections to prevent short-circuits and fires. The airframer completed a final certification demonstration flight on a 787 with the improved battery design on 5 April.

Boeing has deployed teams worldwide to begin the installation of the improved battery on 787s that were in service before the grounding, it says today. The aircraft will be modified in about the same order they were received.

"Kits with the parts needed for the new battery systems are staged for shipment and new batteries also will be shipped immediately. Teams have been assigned to customer locations to install the new systems," says the airframer

It will also begin installing the improved battery on new 787s at its two final assembly lines, and deliveries will "resume in the weeks ahead". Boeing expects to complete all 2013 deliveries it had planned before the grounding, and says it does not expect the battery problems to have an impact on its 2013 financial guidance.

"FAA approval clears the way for us and the airlines to begin the process of returning the 787 to flight with continued confidence in the safety and reliability of this game-changing new airplane," says Boeing chairman, president and chief executive Jim McNerney. "The promise of the 787 and the benefits it provides to airlines and their passengers remain fully intact as we take this important step forward with our customers and programme partners."

McNerney adds that the FAA had set a "high bar" for Boeing's improved battery design. The airframer estimates that its team, working with suppliers, spent more than 100,000 hours developing test plans, building test rigs, conducting tests and analysing the results.

Boeing Commercial Airplanes president and chief executive Ray Conner says Boeing's improved battery design is a "comprehensive and permanent solution with multiple layers of protection".  "The ultimate layer of protection is the new enclosure, which will ensure that even if a battery fails, there is no impact to the airplane and no possibility of fire. We have the right solution in hand, and we are ready to go," he adds.

Source: Air Transport Intelligence news