[UPDATED] FAA has approved Boeing’s certification plan for a redesigned 787 battery system, a first step toward getting the Dreamliner back into the air.

In a statement issued Tuesday, FAA said the certification plan would begin the process to evaluate the 787’s return to flight and requires Boeing to conduct extensive testing and analysis to demonstrate compliance with the applicable safety regulations and special conditions.

The Dreamliner has been grounded since mid-January after two safety incidents related to the aircraft’s lithium ion battery, one at Boston Airport and the other during a flight over Japan. A total of 50 787s around the world have been grounded since.

 “This comprehensive series of tests will show us whether the proposed battery improvements will work as designed,” US Transportation Secretary Ray LaHood said. “We won’t allow the plane to return to service unless we’re satisfied that the new design ensures the safety of the aircraft and its passengers.”

 The battery system improvements include a redesign of the internal battery components to minimize initiation of a short circuit within the battery, better insulation of the cells and the addition of a new containment and venting system, FAA said.

 “We are confident the plan we approved today includes all the right elements to conduct a comprehensive evaluation of the battery system redesign,” FAA Administrator Michael Huerta said. “Today’s announcement starts a testing process which will demonstrate whether the proposed fix will work as designed.”

“Our top priority is the integrity of our products and the safety of the passengers and crews who fly on them,” Boeing chairman, president and CEO Jim McNerney said. “Today’s approval from the FAA is a critical and welcome milestone toward getting the fleet flying again and continuing to deliver on the promise of the 787.”  

Boeing Commercial Airplanes president and CEO Ray Conner said the proposed fix includes three layers of improvements. “First, we’ve improved design features of the battery to prevent faults from occurring and to isolate any that do. Second, we’ve enhanced production, operating and testing processes to ensure the highest levels of quality and performance of the battery and its components. Third, in the unlikely event of a battery failure, we’ve introduced a new enclosure system that will keep any level of battery overheating from affecting the airplane or being noticed by passengers,” Conner said.  

Design feature improvements for the battery include the addition of new thermal and electrical insulation materials and other changes. The enhanced production and testing processes include more stringent screening of battery cells prior to battery assembly. Operational improvements focus on tightening of the system’s voltage range. A key feature of the new enclosure is that it ensures that no fire can develop in the enclosure or in the battery, Boeing said.

FAA granted Boeing permission to begin flight test activities on two airplanes: line number 86, which will conduct tests to demonstrate that the comprehensive set of solutions work as intended in flight and on the ground; and ZA005, which is scheduled to conduct engine improvement tests unrelated to the battery issue. Additional testing may be scheduled as needed, Boeing said.

The certification plan calls for a series of tests that show how the improved battery system will perform in normal and abnormal conditions. The test plans were written based on FAA’s standards as well as applicable guidelines published by the Radio Technical Commission on Aeronautics (RTCA), an advisory committee that provides recommendations on ways to meet regulatory requirements. The RTCA guidelines were not available when the original 787 battery certification plan was developed.

FAA said its engineers will be present for the testing and will be closely involved in all aspects of the process.

 FAA said it will approve the redesign only if the company successfully completes all required tests and analysis to demonstrate the new design complies with FAA requirements.

When the news was announced, Air Lease Corp. chairman and CEO Steven Udvar-Hazy was participating as a panelist at the ISTAT Americas 2013 conference in Orlando. Asked to comment, he said, “I am sure Boeing and 787 customers are looking forward to getting the airplane back into the air. Certainly this is a good step forward.”