The Boeing 787 will remain under intense scrutiny by the US Federal Aviation Administration (FAA) even if the battery problem is resolved within weeks.
Malfunctioning batteries are only one of the aircraft systems under review by the FAA. On 11 January, the agency launched a comprehensive review on all of the 787's critical systems, with a special focus on the electrical power and distribution system and how the electrical system interacts with mechanical systems.
The FAA confirms that review by the Seattle-based Transport Directorate is still ongoing. "The review is supposed to be complete later this year," the FAA says, declining to elaborate further.
The existence of the wide-ranging probe underscores the technical challenges facing Boeing's 787 programme beyond the malfunctions of the lithium-ion batteries that led to a fleet-wide grounding on 16 January. Among them are reclaiming 180min extended operations (ETOPS) authority and overcoming some high-profile glitches that grounded several individual 787s for several days.
Those glitches had raised FAA concerns about the 787's power distribution system, and were later traced to a batch of faulty circuit boards manufactured in Mexico.
After the power distribution problems in December and the battery fire on board the Japan Airlines 787 on 7 January, the FAA decided to launch the sweeping review of the aircraft's most important systems five days later. A second battery failure on board an All Nippon Airways 787 on 15 January prompted a fleet-wide grounding, and focused public and internal attention on the pair of lithium-ion batteries providing supplemental power to the aircraft.
Two months later, Boeing is moving forward with a plan to redesign how the battery manages heat in the event of a malfunction in any of battery's eight cells. The redesign also integrates a new enclosure designed to prevent a fire from starting and a dedicated vent line to make sure no toxic fumes can be released into the passenger cabin.
Boeing expects to demonstrate the safety of the redesigned battery system within weeks, paving the way for return to flight by the operational fleet shortly thereafter.
Some analysts think that the FAA's decision to allow the 787 to return to flight based on Boeing's terms is a sign the agency could soften is stance on any lingering concerns about the overall electrical system.
"If they sign-off on this aggressive plan it indicates they are moving back towards a more cooperative approach with Boeing," says Richard Aboulafia, vice-president of analysis at the Teal Group.
Another factor that has changed since the 787 groundings began in January is that government regulators and the public are far more educated about the aircraft's batteries and electrical systems.
"When these announcements were made everybody was a lot more ignorant about what actually happened than they are now," says Hans Weber, chief executive of the Tecop consultancy.