Slashdot Mirror
Japanese Probe Finds Miswiring of Boeing 787 Battery
NeverVotedBush writes in with the latest installment of the Dreamliner: Boeing 787 saga. "A probe into the overheating of a lithium ion battery in an All Nippon Airways Boeing 787 that made an emergency landing found it was improperly wired, Japan's Transport Ministry said Wednesday. The Transport Safety Board said in a report that the battery for 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 auxiliary unit from causing 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 auxiliary power unit due to miswiring."
So basically, the user reached back behind the power supply while fiddling and bumped the 110/220V switch, and it caught fire. Naturally, they didn't say anything to the tech after setting the switch back besides, "It just caught fire! All by itself!"
The user in this case is a giant airline company, and tech support would be Boeing. The FAA, of course, is the QA manager, who reviewed the call, and after reading the ticket closure notes, facepalmed, leaned back into his chair, and took a deep draft of coffee.
#fuckbeta #iamslashdot #dicemustdie
Outsourcing contractor.
Can't they make an idiot proof power plug?
Because idiots are much more resourceful than ordinary people.
#fuckbeta #iamslashdot #dicemustdie
Really? I am actually quite impressed. The degree of investigation over lighting failures and back up safety systems and all that is pretty awesome. Putting aside my condemnation of corporations like Boeing, this mess isn't damning, but rather assuring. Any finger pointing should be met with a reminder that the plane landed just fine. Granted, I'd be annoyed if my flight was grounded for this nonsense but degree of blame should reflect the problem caused.
Themselves?
Because idiots are much more resourceful than ordinary people.
Behold!
It's the damned metric +/- that causes all the confusion.
Who will it be? Maintenance? Boeing?
All of the above!
I'm skeptical of this story. They are basically saying that somehow the wiring got messed up in such a way that everything still worked, but the battery was improperly charged/discharged by the APU. The evidence they have is some lights that flickered. This seems fishy to me.
If something is miswired, then it's going to be possible to PROVE that as fact. Even if the unit was cut from the aircraft, it would be possible to physically inspect and verify what wire went where. Flickering lights are NOT PROOF of anything being incorrectly wired.
If the drawings don't match the design, you can PROVE that by inspecting the drawings. If the aircraft doesn't match the drawings you can PROVE that by inspecting the aircraft. We have NO proof here.
I'm guessing that somebody in Japan wants to get these aircraft back into the air, bad enough to come up with some story with flimsy evidence and managed to get Japan's version of the NTSB to agree.
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
I was just thinking that..the media will now have their blame game but at the end of the day it was a plane mishap that didn't include charred bodies strewn on the countryside. It was a glitch, that was easily fixed. I could have been much worse.
This whole idea of a wiring error sounds fishy and it seems to be based on flimsy evidence. These kind of things are proven by hard inspection of the aircraft, drawings, and designs not by observing flickering lights. Somebody in Japan wants these aircraft in the air really bad, and I'm betting they managed to talk Japan's version of the NTSB into this idea.
I'm waiting for the final report on this... Before I decide to get on one of these.. Because if this flimsy sounding reason is what I think it is, another plane is going to have a battery fire pretty soon and this time we might not be so lucky.
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
Yes, but commercial airliners aren't built with plugs and sockets. For weight savings, everything is directly hardwired. At least, in pretty much every airliner prior to the 787, and I can't imagine Boeing changing that. Military aircraft are built with plug and socket connectors, but both sides of the connection are big bulky heavy metal components
Do you have a reference for that? It doesn't make sense that field replaceable parts are hardwired in - you'd have to clip the wires to take it out, and every time you clip the wire it gets shorter, so eventually you'd have to run a new wire back to the source.
Even for parts that aren't replaced often, it seems that hardwiring would just increase the chance of error - if everytime they replace an engine someone has to sit down and manually splice 200 separate wires, that seems a lot more trouble prone than plugging in a dozen connectors that were wired in at the factory and tested on the factory test harness to be sure every wire was connected to where it should be.
"Valve" is a generic term, slightly archaic for an electronic switch. Some vacuum tubes are called valves.
http://en.wikipedia.org/wiki/Vacuum_tube
Since a transistor is simply a crystal triode, the terminology is reasonable.
http://www.beatriceco.com/bti/porticus/bell/belllabs_transistor.html
When you say "Japanese Probe" I had an entirely different idea in my head regarding what this story was about.
You do realize that the flickering lights pointed investigators in a particular direction. THEN, after more analysis, they discerned the problem lay in miswiring. The flickering lights are not prima facie evidence of a wiring fault.
A bit more detail would be welcome. As it is, one cannot tell what happened or how many aircraft are affected.
Faster! Faster! Faster would be better!
When I read of it, I felt more vindicated than surprised.
During my tenure in aerospace, I had witnessed more and more of a disregard for detail work. What used to be a good thing called "attention to detail" started being regarded negatively as "being a perfectionist".
The devil is in the details. Thousands of things work perfectly. One does not. This is the inevitable result of overlooking just one detail.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
The 747 has something like 150 miles of wiring. The 787, which was specifically designed to reduce the amount of wiring, still has some 60 miles of wires. There's a lot of opportunity for miswiring something.
The length of the wires isn't a useful metric - it's the complexity of the wiring that causes miswiring.
It wasn't me! I swear it wasn't me! I've never worked on an aircraft in my life!
Sux2bthatguy!!
(Note that Runaway is color vision impaired, and has in fact wired things wrong from time to time.)
"Windows is like the faint smell of piss in a subway: it's there, and there's nothing you can do about it." - Charlie Br
At a guess, I'd say the total length of wiring might be indicative of complexity. The machines that I have worked on that have only a few hundred feet of wiring are generally less complex than machines with thousands of feet of wiring in them.
For comparison, find an old Farmall or John Deere tractor, and compare the wiring to your modern automobile. An elementary school child can figure out the wiring on an 50 to 80 year old tractor. Good luck with your car - experience mechanics have problems chasing down problems, especially intermittent shorts.
"Windows is like the faint smell of piss in a subway: it's there, and there's nothing you can do about it." - Charlie Br
Only if you assume the topology is the same. The 747 is likely to be much more of a "star" topology with traditional circuit breakers. The 787 is more of a "bus" topology with solid-state relays.
AFAIK you are completely incorrect. Just using the 787 for example, the entire thing is built in modules including wiring and all, that are built and tested by subcontractors and then plugged and bolted together at the Boeing assembly plant. All commercial aircraft that I am aware of at least since the 1940s has had connectors. The biggest problem with connectors is not the weight but the unreliability. Each connector is a potential point of failure, so aircraft electrical connectors are actually heavier - they have positive scraping between the two parts of each connection, often have moisture resisting / sealing. and have a threaded ring that holds them together. Then (IIRC) there is an additional set of tabs through which a wire is threaded and itself positively bound - used to be twisted, now I think they use a mechanical crimp. The wire assures that the threaded ring can not unscrew itself due to vibrations.
The most expensive cost for a commercial aircraft after fuel is the cost of downtime - time spent fixing things costs thousands of dollars per hour. Therefore everything on an aircraft is designed to be removed and disconnected quickly, efficiently and safely - including things like wings, tail fins, etc. FAA is not going to allow the mechanics to cut wires and fasten them back together, so again the connectors are designed so that each one can only go one way.
It's easier to be a result of the past, but more fun to be a cause of the future! http://www.spacefinancegroup.com/
Then compare a "modern" car with a very modern car. The huge mess of wires is being replaced by CAN and LIN buses.
They originally planned to use 60 miles of wiring but then they only ordered 60 kilometers of wires so two thirds of the devices are not connected. It's not that big of a problem though since most things are covered by redundancy.
I agree.
It shouldn't have been possible to "miswire" an aerospace battery, the connectors should have been coded, the wires, and the inspectors should have seen and tested this. Battery failure is still a process failure. Unfortunately, process failures are the most systemic failures possible. Lets hope I'm wrong....
andy
A big chunk of the blame should go to whoever designed the connectors. For safety critical systems, it should be physically impossible to connect them in an unsafe configuration.
Yes, and it's extremely annoying if you want to do anything to your own car. It's bad on the same level as proprietary connectors for phones and all that, but unfortunately the amount of people improving their own cars is too low to cause any consumer feedback to manufacturers.
And I don't mean adding stupid spoilers and boost chips and sillyness, I mean stuff like adding an extra pair of high beams that can be operated with the same button as the regular high beams. That will take some serious hacking on a modern car. If car manufacturers were good at making things, this wouldn't be a huge problem, but modern cars do so many things wrong that it's infuriating. Like putting lambertian leds in places where they should have put batwing ones, forcing me to put a diffuser in front of it so that my daughter is able to sleep in her car seat. Or making it a fifteen-minute job to remove the battery for charging it during the winter, when it should take two minutes. Or putting the light that activates when you open the trunk in the far left corner of the trunk, so that it doesn't light up anything if you actually have something in the trunk. I could go on about this for a while...
for i in `facebook friends "=bday" 2>/dev/null | cut -d " " -f 3-`; do facebook wallpost $i "Happy birthday!"; done
a wiring problem could be as simple as using an incorrect thermistor on a Li-ion pack or not wiring a thermistor in at all. These are often used to alter charge/discharge rates in response to the battery pack temperature. A battery will still work in every other respect, except it won't respond accordingly in response to overheating. This is a fairly simple example of what could go wrong to cause a fire that would not stop the battery from working (until it failed by going on fire). The trouble with Li-ion packs is that if this happens (and it does) then the fire can very easily spread to the surrounding cells. I can see how this could cause short voltage spikes that would overcome resistance in a line to "flicker" a light.
I'd just like to add, I may be totally wrong, but I thought I'd weigh in for the fair minded rather than the conspiracy theorists on this one. Also, before anyone assumes I'm a Boeing employee, I'm not. I'm just a bloke who works with Li-ion batteries and who has seen faults similar to this in the past.
Did I ever told you about this guy, I met some years ago, that used an abrasive file over the edges of the HardDisk power connectors, because they "didn't fit" the way he wanted to connect them?
Q: What is worse than a dumb guy?
A: A dumb guy with initiative.