Lane says Boeing ARs approved qualification test procedures, performed conformity inspections, witnessed tests, and approved data and official test documents that were sent to the FAA engineers.
Ali Bahrami, manager of the FAA Transport Airplane Directorate, says it is most important for the agency to be involved in the first five years of a certification program—when the design “is relatively fluid”—and then again late in the program, when certification test flights begin. Communications lines with Boeing were kept open via the ODAs and monthly meetings to “discuss changes.” Regarding the FAA's decision to grant Boeing, late in the program, the authorization to make changes to the certification test plan, Bahrami says it was because changes at that point were more of an “administrative and timing” nature. “We have made it clear if there was some kind of anomaly, the ARs were required to report back to the FAA.”
The FAA's special conditions called for hazards like a runaway thermal condition to be “extremely remote,” leading to only once in 10 million flight hours. Boeing had experienced two events with the 50 787s that had accumulated just 52,000 flight hours.
“We don't get every prediction right every time,” says Boyd. “But we try to build whole families of requirements that trap the safety issues, so even if something happens a little more frequently than expected, we have other parts of the regulations that provide the safety net to keep the airplane safe while we refine our processes and methods.”
When asked why the FAA did not incorporate a test regimen (DO-311) published by RTCA in 2008, the year after Boeing's special conditions were issued, Boyd said RTCA standards are not regulatory requirements.
“We looked at DO-311 and decided we had already incorporated what we needed based on special conditions and our test plan,” he said. “There are aspects in DO-311 that are explicitly more severe than regulatory standards and, in some cases, the special conditions.”
The government industry group met from 2006 to 2008 to develop minimum performance standards and suggested testing protocols for large lithium-ion batteries in aircraft use, as no guidelines existed for the new technology other than the FAA's special conditions.
Boeing systems engineer Jerry Hulm said some of the testing in DO-311 is “extreme” and “very harsh,” including a test that calls for overcharging every cell in the battery. “Those standards are there for a supplier who wants to go develop a battery so they can take [it] and sell to whomever,” he says. “We did an overcharge test and saw what it did, but that wasn't part of the certification. We had other protections.”
On the RTCA committee were representatives from Boeing, Thales, Securaplane and GS-Yuasa. Thales builds the 787 power conversion system and subcontracts to Securaplane and GS-Yuasa. “If any one of those members saw anything in the standards that needed to be addressed from a safety standpoint, we would not have hesitated to address it,” says Hulm.