Old UCAL CA

Published February 20, 2013
Associated Press

TOKYO – A probe into the overheating of a lithium ion battery in an All Nippon Airways Boeing 787 found it was improperly wired, Japan's Transport Ministry said Wednesday.

The Transport Safety Board said in a report that the battery of the aircraft's auxiliary power unit was incorrectly connected to the main battery that overheated, although a protective valve would have prevented power from the APU from doing damage.

Flickering of the plane's tail and wing lights after it landed and the fact the main battery was switched off led the investigators to conclude there was an abnormal current traveling from the APU due to miswiring...





Read more: Japan probe finds miswiring of battery on Boeing 787 'Dreamliner' | Fox News

EWR73FO

Can't be that simple. If it is, big question is which subsidiary partner wired it or was it Boeing people that did it?

Dave Fitzgerald

Not that simple. My guess is that Boeing and the Japanese manuf are learning, down to the atomic level, just how LiPo batteries really work.

Remember, that when this plane was designed, about 5 years ago, LiPo batteries were a lot different and that is ancient tech by now. My guess is that it will eventually work. It has to. Many design decisions were based on the lighter, higher power density batteries and was primarily the reason they went to a more electric system design.

More weight of the older NiCad's, was not feasible from a design trad-off. To go back to NiCads would be weight prohibitive on an already marginaly over weight product, based on performance guarantees to the airlines.

So, Boeing has to make the LiPo batteries work, or there is no economic incentive to buy the plane--weight and performance penalties wouldn't make it economically feasible. They will have to redisgn the batteries on a molecular level to reduce the heating/venting problems. Miswiring may have been the cause of the JAL incident, but the bigger problem is the system as designed did not handle it.

Coto Pilot

What do you mean weight prohibitive? I haven't seen the batteries, what do they weigh 100#'s less, 500#'s less? That is 4 checked bags or 20 checked bags. What is the cost of grounding the fleet?

Dave Fitzgerald

Weight, meaning if they had to replace the LiPo batteries with a NiCad, they would be twice as large and 4 times the weight.

Now factor in that there are little other batteries all over the plane as backups for stuff like...flight controls since there are no hydraulics. Yes there are the main and APU batteries, but there are more, all over. Electric jet...

You quickly start eating into payload that is already on the thin marigin of what Boeing specified for fuel efficiency. Now you have to start paying contract penalties for non-performance. That gets expensive. Hence, my comment of weight prohibitive.

So which will weigh more? A steel box for all the batteries, or a completely redesigned system with NiCads/new battery chargers? That is the design excercise Boeing is going through righ now, and how long other options would take, and get the FAA to buy off on it.

And I'm sure there is more I don't know about. Large design gamble with untested technology--bit them big time. Boeing has to build a new battery system, and we have the conservative FAA. Airbus just tells their customers, bring your plane on back before 150 hrs so we can rebuild the wings before they fall off. Different agency, different sources of income/payoffs.

EWRflyr

You seriously did not just say that!?

Conservative FAA? How many items can each one of us point to that shows the FAA is anything but conservative and bend to the will of the airline industry lobby?

Maybe you mean they are being conservative about their actions going forward in regards to allowing the 787 to fly again. I would accept the statement in that case only.

Dave Fitzgerald

No, I did mean conservative FAA. They are very conservative when it comes to aircraft certification and design standards. Actually rather jurrasic.

Flt Ops? Hehh, that's good enough for government work. Different department, along with air carrier PO's.