Boeing has received approval from the U.S. Federal Aviation Administration (FAA) on the company’s plan to test and certify improvements to the 787’s battery system. Successful completion of each step within the plan will result in the FAA’s approval to resume commercial 787 flights.
“Working with internal and external experts in battery technology, we have proposed a comprehensive set of solutions that provide three layers of improvements in the battery system,” said Ray Conner, president and chief executive officer of Boeing Commercial Airplanes. “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”.
The new production processes incorporate changes to the battery’s design and add more stringent screening of the battery cells after production. The new battery design includes a number of changes including the addition of more thermal and electrical insulation materials to the cells and the battery. Changes to the battery charging limits will also improve on-board operation. Lastly, in the unlikely event of a battery failure a new battery enclosure eliminates any potential for fire and allows the airplane to safely continue on to its destination.
Boeing made its certification plan proposal to the FAA in late February. The agency agreed that the proposed changes and the detailed test plans address the conditions that resulted in suspension of 787 operations. The FAA also granted Boeing permission to begin flight test activities on two airplanes to demonstrate that the comprehensive set of solutions works as intended during normal and abnormal flight conditions.
The test plans were written based on the FAA’s standards as well as the 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. The most stringent of these tests requires that Boeing demonstrates that the new enclosure will work as intended even the highly improbable event that all eight cells of the battery fail at the same time.