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. Additional details of the new design will be provided by Boeing in the days ahead.
Boeing made its certification plan proposal to the FAA in late February. Today the agency agreed that the proposed changes and the detailed test plans address the conditions that resulted in the suspension of 787 operations.
The FAA also 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.
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 the 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."We have a great deal of confidence in our solution set and the process for certifying it," said Conner. "Before 787s return to commercial service, our customers and their passengers want assurance that the improvements being introduced will make this great airplane even better. That's what this test program will do."