# What's up with the worldwide Dreamliner grounding? **URL:** \ **Category:** Factual Questions\ **Created:** [January 18, 2013, 12:18am UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566 "2013-01-18T00:18:00Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [January 18, 2013, 1:34pm UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/21 "2013-01-18T13:34:00Z")
Note that the consequences of inflight fire can be [very severe](http://en.wikipedia.org/wiki/ValuJet_Flight_592). ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [January 18, 2013, 2:03pm UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/22 "2013-01-18T14:03:21Z")
> [@lisiate](#): > > So its all down to the batteries? What’s the weight advantage in a 110 tonne airplane (dry weight) by using Lion batteries rather than more well tested designs? Surely it can’t be more than 2 or 3 per cent. Which leads me to believe that the design brief was so biased towards weight saving that other considerations went out the window. Or has airliner design reached that point where a 1 or 2 per cent advantage become that vital? Lithium ion batteries are between 1/2 and 1/4 of the weight of other types of batteries that deliver the storage and current levels. It’s not that Li-ion batteries aren’t well tested, they are. But they must be made to a certain quality and specs in order to be safe. They certainly can be safe - they are routinely used in implantable medical devices like pacemakers where light weight, small size, reliability, and long life (up to 15 years of continuous use) are needed. Scaling up to an airliner, though, and making sure that not only are they correctly manufactured but correctly installed and used is a slightly different problem. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [January 18, 2013, 2:07pm UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/23 "2013-01-18T14:07:33Z")
> [@JRDelirious](#): > > it would seem to me reasonable it would go similarly to an automobile’s electrical system, where the system includes generators (in the engines) and batteries in line with each other and the batteries serve not just as starter/backup power but also as a way to stabilize and make constant the base load for essential functions, so the general load does affect the batteries anyway. Agree. From a “flow of energy” standpoint, an automobile battery is basically just a big capacitor. An aircraft that uses a battery across the main power bus operates in the same way. However, unlike an automobile, there may be provisions to allow the battery to be charged from a hangar or ground cart receptacle when the plane is on the ground. As you mentioned, a battery across the main power bus may also have another benefit: it can stabilize the DC power bus. When the impedance of a load dips down for a few milliseconds upon startup, the battery will be the main provider of the inrush current to the load, not the generator. This is because the battery responds “faster” than the generator during dynamic conditions. (The same is true for big electrolytic caps in power supplies.) If the battery were not there, the bus voltage may sag to an unacceptable level during the event. But there are obvious risks with using batteries. Especially on a 270 VDC system. If there’s an arc somewhere, the battery will happily feed the arc. And DC arcs are not… good. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [January 18, 2013, 2:42pm UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/24 "2013-01-18T14:42:11Z")
> [@bahimes](#): > > I can’t quite envision why lithium ion batteries of sufficient size to cause sparks to fly when the Halon system operates would be used. The halon doesn’t cause the sparks, it just changes their color. The sparks are from the burning lithium, and it doesn’t require a large battery. Later in this post I have a link that shows this quite well. Whatever you do, don’t use water on a lithium fire. That results in lithium oxide and hydrogen gas, which also burns nicely in normal atmosphere, resulting in more water… > [@](#): > > If so, I would assume that the casing/shielding/mounting systems would be designed with pretty efficient cooling during operation. Of course they are - these batteries are sealed, have shielding, protective casings… but damage can lead to problems, whether during installation/maintenance or from overcharging during use. > [@](#): > > By all means ground the planes until cause effect and prevention can be assured. > That said, I hadn’t heard of in-flight issues, only on the ground which is when I would believe that the onboard UPS might actually be relied upon for certain maintenance/test functions. There have now been in-flight issues. Fortunately, safety designs were sufficiently robust that the fire was contained and the airplane landed safely. > [@](#): > > Lithium batteries in discharge mode grow very hot, very fast. “Hot” as in thousands of degrees, able to melt metals, able to melt table salt. A burning lithium fire will burn even more intensely in the presence of water, carbon dioxide, and quite a few other things we don’t think of as burnable. Last summer I took a small, malfunctioning Li-ion battery to my backyard fire pit and set fire to it, to see for myself what would happen. It was brief but pretty intensive. YouTube is full of idiots playing with Li-ion batteries and fire. [This one shows the hazards of puncturing one.](https://www.youtube.com/watch?v=FXEtE9BPwhU) Airliner batteries are in metal carriers in part to avoid this, and also in parts of the airplane idiots with pointy objects can’t access. [This is a fire resulting from overcharging a battery](https://www.youtube.com/watch?v=FXEtE9BPwhU). In this case, it was a deliberate demonstration. When they “pop” they can also spray flaming materials. The exterior wrap on Li-ion batteries not only seal the interior from the outside air with its oxygen and other potential burnables, it helps contain the inner bits in events like this, reduce flying sparks, and to minimize the spread of fire. [This video is from a different sort of Li battery](https://www.youtube.com/watch?v=MTFmPehXA30), the person making the video opened the batteries and removed the lithium strips, balled them up, and set the lump on fire. This one shows the type of sparks a lithium fire can throw. It also left a small crater in the concrete where the fire burned. You might also note that in all of these cases the batteries/lithium did require some abuse before igniting. For the batteries, safety measures had to be defeated, either getting through the exterior case or defeating the inbuilt protections against overcharging. Even the disassembled battery strips did not instantly ignite, it’s not pure lithium and some lithium compounds are more hazardous/ignitable than others and this is factored into construction of batteries, their intended use, and their availability to the public vs. trained personnel. All of which sounds quite scary. On the other hand, Li-ion batteries are becoming ubiquitous and are largely trouble-free. It’s one of those very useful technologies than can be safely used… if you follow the rules. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [January 18, 2013, 2:43pm UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/25 "2013-01-18T14:43:27Z")
> [@JRDelirious](#): > > An airplane on the ground in Boston a few days earlier had an actual battery compartment fire detected after landing and deplaning. That one was due to over-charging the batteries if I recall correctly. ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [January 18, 2013, 3:19pm UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/26 "2013-01-18T15:19:28Z")
I hesitate to ask what might happen to these big, bad batteries should a plane actually crash. Would they spark into a fierce, hot fire capable of igniting spilled jet fuel? Assuming they’re placed in the most crash-safe part of the plane, would that be right next to the flight recorders, and could a battery fire damage them? ---
**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\ **Post date:** [January 18, 2013, 4:18pm UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/27 "2013-01-18T16:18:01Z")
My desperate hope and WAG is that these batteries should be designed so that they won’t catch fire in any survivable crash. Or at the very least, that the fuel will catch fire from other crash-related causes before the battery ignites. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [January 18, 2013, 4:49pm UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/28 "2013-01-18T16:49:28Z")
> [@kunilou](#): > > I hesitate to ask what might happen to these big, bad batteries should a plane actually crash. Would they spark into a fierce, hot fire capable of igniting spilled jet fuel? Assuming they’re placed in the most crash-safe part of the plane, would that be right next to the flight recorders, and could a battery fire damage them? Fuel doesn’t need any help from a battery to ignite in a crash; that’s just about a given, unless the crash is really minor (like skidding off of a runway after a controlled landing). FDR’s/CVR’s are already designed to be extremely fire-resistant. I suppose if a battery fire starts well before the plane crashes, then it would have a head-start on wrecking the recorders before the plane even crashes, but that assumes that the battery is placed pretty much in contact with the recorders. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [January 18, 2013, 4:57pm UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/29 "2013-01-18T16:57:02Z")
> [@lazybratsche](#): > > My desperate hope and WAG is that these batteries should be designed so that they won’t catch fire in any survivable crash. Or at the very least, that the fuel will catch fire from other crash-related causes before the battery ignites. ^ This. By the time an impact is severe enough to start batteries burning the fuel has probably already ignited anyhow. As there is typically much, much more fuel than batteries even on a Dreamliner, it’s the fuel fire that will be the major problem and/or cause of fatalities. Quite a bit of the rest of an airplane will burn, too. Efforts are made to make parts of the cabin fire resistant in the sense of giving you a bit more time to get the heck out of the thing but post-crash fires are can’t really be eliminated with modern technology and materials. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [January 19, 2013, 12:09am UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/30 "2013-01-19T00:09:54Z")
Dreamliner bodies are made of CF, which is almost certainly more flammable than plain aluminium, given the amount of epoxy resin involved. As a fire hazard, that sounds like a serious one to me. There seems to be [some indication](http://www.cbsnews.com/8301-505123_162-57564789/overcharged-batteries-eyed-in-boeing-dreamliner-fires/) that the batteries are being overcharged. WTF? Even [electric-cars-are-for-girls.com](http://electric-cars-are-for-girls.com) recommends using battery management hardware, why would you save ten pounds on a big plane full of people and leave that out??? ---
**Author:** ![KCB615](https://avatars.discourse-cdn.com/v4/letter/k/ea666f/32.png) [@KCB615](https://boards.straightdope.com/u/KCB615)\ **Post date:** [January 19, 2013, 12:50am UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/31 "2013-01-19T00:50:24Z")
> [@For You](#): > > Dreamliner bodies are made of CF, which is almost certainly more flammable than plain aluminium, given the amount of epoxy resin involved. As a fire hazard, that sounds like a serious one to me. The carbon fiber composite used on the 787 does not support combustion. The fire tests that were done on that composite material showed a greater resistance to burnthrough than the duraluminum currently in use on most large frame aircraft. ---
**Author:** ![iamnotbatman](https://avatars.discourse-cdn.com/v4/letter/i/858c86/32.png) [@iamnotbatman](https://boards.straightdope.com/u/iamnotbatman)\ **Post date:** [January 20, 2013, 7:54am UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/32 "2013-01-20T07:54:21Z")
> [@Broomstick](#): > > All of which sounds quite scary. On the other hand, Li-ion batteries are becoming ubiquitous and are largely trouble-free. It’s one of those very useful technologies than can be safely used… if you follow the rules. Then why have I heard so many stories of laptop or phone batteries spontaneously combusting (and even more stories, including personal experience, of such batteries ‘bloating’ or overheating, characteristics that could easily lead to self-caused physical abuse). In every case are these traceable to user-caused physical abuse? The sense I have gotten from the media reports is that there is just some small probability that, whether due to a flaw in the charging system or a defect in the battery itself, that one will randomly go bad and cause problems. If so, it seems somewhat arrogant to put these guys on airplanes if there is no sure way of putting the fire out; surely defects (in the electrical system or battery itself) will eventually happen. In fact, this is the sort of story you see over and over again in the history of air disasters, and the DC 10 is a perfect example, where the door they designed was fundamentally asking for trouble, despite efforts to throw safety systems on top of the flawed design. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [January 20, 2013, 11:57am UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/33 "2013-01-20T11:57:35Z")
> [@iamnotbatman](#): > > Then why have I heard so many stories of laptop or phone batteries spontaneously combusting (and even more stories, including personal experience, of such batteries ‘bloating’ or overheating, characteristics that could easily lead to self-caused physical abuse). In every case are these traceable to user-caused physical abuse? Of course not. There can be defects in manufacture. This may be news to some people but the quality control on items manufactured to be part of airplanes is supposed to be considerably higher than that for consumer products like cell phones. Despite this, defective parts can and have made their way onto airplanes. There can be defects in handling. This can range from abuse during shipping to the end user causing trouble. This doesn’t have to be overt, like stabbing the battery with an icepick, it can be as simple as blocking the cooling vents on a product leading to overheating the device with bad results for the battery. On airplanes, the batteries have both physical shields around them and cooling systems to prevent these problems. Overcharging a lithium battery is, of course, bad news as we all know. The incident in Boston was caused by overcharging lithium batteries with a ground-based auxiliary power unit, something that just won’t happen in-flight. It’s a bit like saying there is a non-zero chance of the fuel tank exploding. Well, yes, there is and it has happened. It’s extremely rare, however. There is a non-zero chance of an engine coming apart while running. It has happened - actually, it has happened more often than fuel tanks have exploded. Despite all this, the odds of such a thing happening are extremely low, so much so that aviation is, despite all the inherent potential hazards, our safest form of transportation overall. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [January 20, 2013, 11:58am UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/34 "2013-01-20T11:58:21Z")
> [@For You](#): > > Dreamliner bodies are made of CF, which is almost certainly more flammable than plain aluminium, given the amount of epoxy resin involved. As a fire hazard, that sounds like a serious one to me. The [787](http://www.compositesworld.com/articles/boeing-787-update) is mostly made of Toray T800S prepreg unidirectional tape. Prepregs have as little resin as they can possibly manage. It isn’t anything like the ordinary fibre reinforced composites that most people are used to. The idea is to get the maximum possible amount of fibre, and only the minimum resin needed to bond the fibres. Because the tape is unidirectional, the fibres all lie together with minimum gaps. The tape comes already impregnated with a very carefully controlled amount of resin, and is autoclaved to cure. The tape is at least 60% carbon fibre. Typical fibreglass layup used for domestic use - like pools, tanks, ordinary boats, is only 22% fibre. As noted above by **KCB615** the actual result is less combustible than aluminium. This isn’t all that great an achievement. Aluminium isn’t exactly the first choice in fire resistance. ---
**Author:** ![iamnotbatman](https://avatars.discourse-cdn.com/v4/letter/i/858c86/32.png) [@iamnotbatman](https://boards.straightdope.com/u/iamnotbatman)\ **Post date:** [January 20, 2013, 12:29pm UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/35 "2013-01-20T12:29:34Z")
> [@Broomstick](#): > > Of course not. > It’s a bit like saying there is a non-zero chance of the fuel tank exploding. Well, yes, there is and it has happened. It’s extremely rare, however. There is a non-zero chance of an engine coming apart while running. It has happened - actually, it has happened more often than fuel tanks have exploded. Despite all this, the odds of such a thing happening are extremely low, so much so that aviation is, despite all the inherent potential hazards, our safest form of transportation overall. Your argument bears an uncanny resemblance to the rationalizations in favor of the DC10’s outward-swinging cargo doors. In the case of the batteries, there is a trade-off of weight vs risk, in the case of the cargo doors, the trade-off was more cargo room vs risk. Money vs risk. In the case of the door, the exact same argument applies. There was more care in designing redundancies and checks to make sure the door is properly closed, that the locking mechanism is risk-averse, etc. But ultimately the risk was obvious: you were asking for trouble. There is a name for this kind of fallacy, the same kind of thinking that lead to the DC-10 problems, but I can’t place the word at the moment (Langeweische explained it in one of his books) – that you are somehow smart enough to think of all of the possible failure modes in a system that is inherently unstable (such as a door that is not self-sealing under pressure, or a fire that is not auto-extinguishing, or even capable of being extinguished (!)). Yes, the batteries I’m sure have better quality control than your average batteries, but still accidents will happen. You cannot deny this. And it’s silly to bring fuel into the picture – obviously there are alternatives here, whereas for fuel there are none. Look, I’m not trying to scare people; I’d fly on the 787 despite my worries. There is risk in any flight, But c’mon, do you really not see my side here? ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [January 20, 2013, 11:31pm UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/36 "2013-01-20T23:31:21Z")
> [@Francis\_Vaughan](#): > > Aluminium isn’t exactly the first choice in fire resistance. Well, right, aluminum powder was the fuel component in the NASA Shuttle’s SRBs. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [January 20, 2013, 11:38pm UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/37 "2013-01-20T23:38:48Z")
> [@iamnotbatman](#): > > Your argument bears an uncanny resemblance to the rationalizations in favor of the DC10’s outward-swinging cargo doors. Yes, I am aware of that. > [@](#): > > There is a name for this kind of fallacy, the same kind of thinking that lead to the DC-10 problems, but I can’t place the word at the moment (Langeweische explained it in one of his books) – that you are somehow smart enough to think of all of the possible failure modes in a system that is inherently unstable (such as a door that is not self-sealing under pressure, or a fire that is not auto-extinguishing, or even capable of being extinguished (!)). The problem is that aviation is rife with compromises and there are so damn many potential failure modes. > [@](#): > > Yes, the batteries I’m sure have better quality control than your average batteries, but still accidents will happen. You cannot deny this. And it’s silly to bring fuel into the picture – obviously there are alternatives here, whereas for fuel there are none. All lithium batteries have some risk of thermal runaway, where the heating/fire turns into a self-reinforcing loop. Some types have more risk, some less. Some store more energy, some less. Some weigh more, some less. Down the road we may decide heavier, less energy dense Li batteries are safer than what are currently installed in the 787. Or it may be decided that the current ones, with certain safeguards, represent an acceptable level of risk. You can not, however, have a completely safe Li based battery. Lithium is just too reactive. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [January 20, 2013, 11:46pm UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/38 "2013-01-20T23:46:41Z")
> [@For You](#): > > Well, right, aluminum powder was the fuel component in the NASA Shuttle’s SRBs. In fairness, almost any powdered metal is a problem. Powdered titanium is a serious hazard and can ignite on contact with air - something that makes machining it an issue. Steel wool will burn, although won’t support a fire in air. Bulk metals are much safer, due to the much reduced surface area, but the common notion that metals don’t burn or are safe in a fire is only a matter of degree. As the Royal Navy found, a destroyer with an aluminium superstructure burns with devastating results. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [January 21, 2013, 12:00am UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/39 "2013-01-21T00:00:37Z")
> [@Broomstick](#): > > The incident in Boston was caused by overcharging lithium batteries with a ground-based auxiliary power unit, something that just won’t happen in-flight. This appears not to be the cause, from what was announced today: _[Safety Board Rules Out a Cause for 787 Battery Fire](http://www.nytimes.com/2013/01/21/business/global/ntsb-rules-out-a-cause-for-battery-fire-on-787-dreamliner.html?_r=0)_: "National Transportation Safety Board said an examination of the data from the plane’s flight recorder indicated that the battery `did not exceed the designed voltage of 32 volts.’ " ---
**Author:** ![lisiate](https://avatars.discourse-cdn.com/v4/letter/l/f05b48/32.png) [@lisiate](https://boards.straightdope.com/u/lisiate)\ **Post date:** [January 21, 2013, 1:05am UTC](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566/40 "2013-01-21T01:05:02Z")
So what will an extended investigation mean for Boeing as a company? Will there be cancelled orders? Does the AIrbus A350 use Lithium Ion batteries as well? [Previous page](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566.md?page=1) [Next page](https://boards.straightdope.com/t/whats-up-with-the-worldwide-dreamliner-grounding/647566.md?page=3)