The NTSB announced on January 20th that the battery on the JAL 787 in Boston did not exceed the 32 volts it was designed to handle. This statement seems to indicate that the NTSB does not consider the lithium-ion battery the culprit in the JAL fire and is looking at other components of the battery system including the charger. The JTSB investigators have suggested that the issue on the ANA 787 was due to the battery being over-charged.
Here's the text of the NTSB's latest statement:
NTSB Provides Third Investigative Update on Boeing 787 Battery Fire in BostonThis may indicated that the battery system on the 787 may suffer from not one but two different issues and may pose a difficult challenge for Boeing to get the airplanes flying again.
January 20
WASHINGTON - The National Transportation Safety Board today released a third update on its investigation into the Jan. 7 fire aboard a Japan Airlines Boeing 787 at Logan International Airport in Boston.
The lithium-ion battery that powered the auxiliary power unit has been examined in the NTSB Materials Laboratory in Washington. The battery was x-rayed and CT scans were generated of the assembled battery. The investigative team has disassembled the APU battery into its eight individual cells for detailed examination and documentation. Three of the cells were selected for more detailed radiographic examination to view the interior of the cells prior to their disassembly. These cells are in the process now of being disassembled and the cell's internal components are being examined and documented.
Investigators have also examined several other components removed from the airplane, including wire bundles and battery management circuit boards. The team has developed test plans for the various components removed from the aircraft, including the battery management unit (for the APU battery), the APU controller, the battery charger and the start power unit. On Tuesday, the group will convene in Arizona to test and examine the battery charger and download nonvolatile memory from the APU controller. Several other components have been sent for download or examination to Boeing's facility in Seattle and manufacturer's facilities in Japan.
Finally, examination of the flight recorder data from the JAL B-787 airplane indicate that the APU battery did not exceed its designed voltage of 32 volts.
In accordance with international investigative treaties, the Japan Transport Safety Board and French Bureau d'Enquêtes et d'Analyses pour la sécurité de l'aviation civile have appointed accredited representatives to this investigation. Similarly, the NTSB has assigned an accredited representative to assist with the JTSB's investigation of the Jan. 15 battery incident involving an All Nippon Airways B-787. Both investigations remain ongoing.
Further investigative updates on the JAL B-787 incident will be issued as events warrant. To be alerted to any updates or developments, please follow the NTSB on Twitter at www.twitter.com/ntsb.
Boeing is pushing to get the airplanes back in the sky and have indicated to customers that they have a plan in work to present to the FAA. Given that the investigation in Japan and the US have not concluded the root cause of either incident nor has the FAA signed off on any corrective measures, one has to deduce that the Boeing plan is more of a temporary preventative measure which would entail frequent checks of the battery system rather than any permanent fix or redesign of the battery system.
Despite all the publicity surrounding the battery issue, Boeing's 787 customers see no changes in the delivery plans despite Boeing's hold on deliveries. Norwegian says they still expect their first 787 to be delivered in April (on lease from ILFC) according to information provided to them by Boeing. Meanwhile Boeing continues 787 production with another 787 entering final assembly on January 23. The Everett and Charleston flightlines will be filling up quickly and Boeing maybe hard-pressed to clear that backlog when they have the green light to fly the 787 again but it will all depend on what the NTSB and the FAA have to say at the end.
I anticpate some good news for the 787 program tomorrow. A bankruptcy judge in New York is expected to have a hearing on the restructured (renegotiated) aircraft purchase contracts that American Airlines will present. I think it may be approved tomorrow and if so then Boeing can add 42 787s (20 787-8 and 22 787-9) to their backlog by the end of this week.
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6 comments:
Sadly, I can't see frequent checks of the batteries being any use if they haven't narrowed down the root cause(s) of the incidents. If you don't know the cause, you cannot know what to check for. And it may not even be the batteries at fault.
More acceptable might be temporary alterations to mitigate the effect of any fires.
But I doubt either (or a combination) would satisfy the FAA if Boeing have not understood the root cause(s).
This is beginning to look really bad for Boeing. I am starting to get the impression that they don't actually understand deeply enough some of the electrical systems in their own plane.
If Boeing didn't understand the electrical systems in their planes, those planes would never fly. This is a problem with the battery systems and they'll get it fixed, sooner or later. I see no reason why temporary checks on the batteries shouldn't work if they are thorough.
Sorry, I think you misunderstood the battery voltage issue. The fact that the 32V voltage limit was not trespassed shows that the battery charger did not exceed the battery charge. A lithium ion battery is first charged with a constant current, and then a constant voltage. In the first phase, the current has to be limited to 0,5 to 1C. There can be an issue here. And then, in the second phase, if the voltage is OK, no problem.
For me, Boeing simply picked the wrong battery technology because Lithium ion was new at the time of design. The factory of the battery charger company in the US aleady burned once due to battery instability.
If this is true, Boeing will have to change the battery type and this can take a very very long time, not months but a year or more.
http://www.aviationweek.com/Article.aspx?id=/article-xml/awx_01_24_2013_p0-540670.xml&p=1
for what it's worth....
TravelingMan:
I said 'understand deeply enough'. Batteries are part of the electrical system, and the fact that the problems occurred, and they haven't yet got to the bottom of why, shows they do not understand the electrical system well enough.
Hopefully (and very probably) that lack of understanding is only true for the new battery electrical systems.
The electrical fire during flight test should also be taken into account.
This is not a criticism of Boeing. Electrical systems - especially ones that have to carry significant amounts of power - are difficult to design at the best of times. These problems will be compounded when designing them to be light and to cope with differing pressures, temperatures and vibrations.
The fact that the 787s have flown successfully for so long shows that whatever happened could be an edge or corner case that has been missed - extreme circumstances that are rarely encountered. And edge/corner cases can be exceptionally hard to find.
An ex-colleague of mine spent six months trying to work out why a computer battery blew up during charging, which prompted a recall of thousands of units. That was back in 1985 or 1986. The only way of reproducing the problem was to leave many computers on for months at a time until another battery blew. The root cause turned out to be two PCB tracks that were slightly too close together.
A hard and very expensive lesson was learnt, the expense being in engineering resource, money and reputation. Boeing and their suppliers may get a similar lesson.
I hope they find the root cause soon, and develop a suitable fix.
http://www.ntsb.gov/news/2013/130129b.html
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