More Boeing Q&A on the 787 battery issue
A press release detailing 787 battery solutions outlined in Boeing’s Thursday’s Tokyo press conference is here.
Press coverage from last night’s briefing:
Boeing today held a special question-and-answer session follow-up to the Tokyo press conference. Ron Hinderberger, Vice President, 787-8 Engineering, Boeing Commercial Airplanes, is the representative. A running synopsis:
The FAA recently approved certification plan, part of a comprehensive process that is an important milestone. The FAA has approved the changes and we will have a series of ground and flight tests and a series of analyses to lead to certifying the airplane.
[Recaps the changes described at the Tokyo press conference.]
- The enclosure material is made of stainless steel. It does not have a dedicated cooling system. Found during testing of the battery that the battery was actually operating in temperatures that were less than originally thought when designed. One test we will do to put the battery in the enclosure and conduct tests to demonstrate appropriate temperature margins.
- Q: Japan’s equivalent of the FAA says it is inappropriate to suggest a timeline and the FAA says it will go slow. How does Boeing’s suggestion the planes will return to flight within weeks? A: The plan went through three detailed, line-by-line review with the FAA and the conclusion was that this is indeed sufficient to meet certification requirements. The reason we are confident of plan with one flight test is we are confident with detail laboratory testing with greater detail and monitoring than we could on the airplane. As you’re aware we like to operate our test teams to a plan. Three tests are completed. More testing underway and hope to have the flight test within a week or two, when all data will be sent to FAA for review. It is inappropriate for me to suggest a timeline. That said, the FAA has been involved along the way.
- Water condensation, in our effort to examine all root causes, was one of a number of simulated failure conditions to emulate the failure in the cells. This was one of the ways a short circuit could happen. Simulation did create a short that led to venting. But it is inappropriate at this time to speculate that this is the probable cause. If this proves to be the case, the drain holes and insulation between the cells will prevent it again.
- The battery blue case sits inside the enclosure case. The venting tube is titanium. Diameter is 1 inch. Steel box is 1.25 inches thick. The battery envelope has not changed. The venting tube goes to a new hole in the fuselage, but doesn’t require new certification requirements except to show the vapors don’t get re-ingested into the airplane, which is validated by lab testing. Testing we’re doing will be re-run for certification process but this testing has been going on for weeks in preparation for defining the end solution for the airplane.
- Batteries that are in service, we have a record, we know how each battery and cells behaved when originally manufactured. We know today which cells would not pass the battery test. When they come back these cells will be automatically rejected. The batteries will then be refurbished.
- [More recap from Tokyo press conference.]
- The containment box is air tight, a sealed container.
- 150 pound weight increase is aggregate for the two batteries. Retaining the lithium-ion battery is a result of a number of trades in selecting it to begin with and those remain valid today. (Highly paraphrased.)
- Not aware of any history of Boeing previously considered a containment box, nor of anyone in automotive history or elsewhere that would have suggested a containment box.
- Q: You have explicitly and implicitly challenged NTSB findings on thermal runaway and other conclusions. A: I don’t know that we would characterize the seriousness of events differently. The NTSB has a different view of thermal runaway than we do. Our view of seriousness of this incident is demonstrated by the thousands and thousands of hours we’ve put in and the people drawn from the Boeing Enterprise and from outside Boeing.
- ZA005 and Line 86: one airplane will do wheels-up flight test, the other an on-airplane ground test. ZA005 will be the ground-test airplane.
- With these changes we think the likelihood of a repeat is very unlikely, more in line with what we intended. With that said I can’t say we will never have a failure. (Echoes Mike Sinnett from the Tokyo press conference: “parts fail”)
- RTCA commission generated lithium-ion set of requirement after original work containing 104 requirements in the document. Some went beyond requirements established in the special condition. As a result of this change, we have elected to certify this change to go beyond special conditions and reach into DO-311. In working with FAA we determined it would be best to go with changes in DO-311. The most significant change is the venting should be able to accommodate the venting of all eight cells simultaneously. This is three times what has been required.