FAA, Boeing Grilled About Battery Certification
By John Croft
Source: Aviation Week & Space Technology
April 29, 2013
John Croft Washington
A November 2006 fire that destroyed a 10,000-sq.-ft. Securaplane
Technologies building in Tucson, Ariz., sent Boeing and its team back to the drawing board to reevaluate whether its chosen battery, chemistryand safety systems for the 787 were up to the job.
Securaplane, the battery-charging system contractor, had been testing a first-generation GS-Yuasa lithium-ion battery, which failed, causing the fire.
More than six years and several more battery incidents and fixes later,
Boeing has constructed an increasingly comprehensive and complex
mechanical and software safety net around the battery to protect the
aircraft from any lurking “unknown unknowns.” What has remained the
same is Boeing’s commitment to the size, weight and energy-density
advantages of lithium-ion batteries with cobalt-coated cathodes.
The NTSB questioned Boeing and the FAA about that troubled path to certification during an investigative hearing April 23-24, part of its
continuing probe into the failed-battery incident on a Japan Airlines
787 in January.
The review was not meant to find the root cause of the failure, which
continues to elude investigators, but to understand why the FAA-approved
special certification conditions for the battery did not prevent the
failure. Also on the agenda was whether FAA’s delegation of authority to
Boeing prevented the regulator from being close enough to testing the
The FAA and Boeing rigorously defended both the certification and
delegation of responsibility, saying the special conditions were
“robust enough” and that delegation is the only way the agency can
keep pace with technology. “One thing we can’t do is wait until we know
everything before we field a new technology,” says Steve Boyd, manager
of the FAA’s airplane and flight-crew interface branch.
Given its limited manpower, the FAA largely depends on authorized
representatives (AR) to develop test plans and to witness tests. ARs
work for companies which, like Boeing, have been granted organization
designation authorization (ODA) by the agency. Doug Lane, the director
of regulatory administration for Boeing Commercial Airplanes, says there
are 950 people in the program, about two-thirds of whom were working
full-time as ARs during the regulations compliance phase of the 787
certification program. The FAA, in contrast, had the equivalent of about 40 full-time engineers on the 787 program, with an average of 30 years of experience in the group.
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.li 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 equirements.“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 tections.”
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 HulmThe risk assessment for the batteries, in part, came from GS-Yuasa’s
experience in building more than 14,000 lithium-ion cells for its
industrial customers since 2001.From the FAA’s perspective, the nine special conditions were performance-based and flexible enough to cover whatever chemistry was used. Those conditions—meant to control lithium-ion-specific issues such
as over-charging, over-discharging and cell flammability—cast a wide
safety net with the flexibility that, so far, has covered the evolution
of the battery through four design iterations.Though there were more than 100 battery tests in the qualification/certification program, key to proving compliance with the special conditions were “abuse” tests—ne of which called for a nail
to be driven through a cell to force a short-circuit.
The testing, which GS-Yuasa says it performed at least 3-5 times for
each generation of batteries, did not lead to thermal runaway in
“There was no propagation to other cells,” says Boyd. “That was the
basis of our conclusion that Boeing’s analysis was reasonable.” In
hindsight Boeing and the agency concede that certain battery tests to
show compliance with FAA special conditions were too lenient.
“One particular test—nail penetration—resulted in a short that wasn’t
as energetic as we’ve seen in service,” says 787 chief project
engineer, Mike Sinnett. “What we’ve since found out, in retrospect, is
that we don’t feel [the nail test] was conservative enough.”
En route to the new battery system being retrofitted on the grounded
fleet, Boeing has made significant changes. After the Securaplane
factory fire, attributed to the battery control system being
disconnected, Boeing stayed with cobalt-based lithium-ion chemistry, but
built-in an additional battery monitoring unit.
Three years later, while testing the electrical subsystem at Hamilton
Sundstrand’s Airplane Power Systems Integration Facility, one cell in a
787 battery experienced thermal runaway and vented. As a result, the
third-generation battery included better sealing of the box,
enhancements to the monitoring unit and a fuse-like “latch” function
that requires a battery with too low a charge to be serviced by Boeing
before being used again.