So let's see. We put the battery in a fireproof box with no oxygen. So now when it shorts it will get really hot and although it won't actually catch fire, the plane will lose electric power. Since just about everything on the 787 airliner runs on electricity, aren't we still screwed?
your goal should be to limit operation to a range you can carefully test for proper behavior. And you instrument the hell out of it to make sure operations stay in this range.
To this end, lowering the maximum voltage and increasing the minimum voltage sound like the most important changes that were made. Better control of operating temperature and other environmental factors is also called for - from what I've read it isn't clear that was done. (it may be because it's infeasible.)
Like all the other commenters here, I'm pretty uncomfortable with the apparent focus on trying to effectively manage a catastrophic failure should it occur. In my experience the sorts of changes you tend to make when you attempt this can actually end up making things worse. The obvious example in the present caseis that more insulation may prevent a fire from spreading but it can also cause more heat buildup.
But the really appalling thing is the overconfident language used in the announcement. It's an indication that the same sorts of problems that led to the Challenger disaster are also in play here. Specifically, this is what happens when there's a long management chain and the engineers at the bottom who are actually doing the work are qualifying their statements in various ways, but as information flows up the chain the qualifications are getting lost and the picture takes on an increasingly rosy glow.
Of course it's entirely possible that the changes Boeing has made will solve the problem. And I certainly don't have sufficient expertise in this specific problem domain to claim otherwise. But having spent 20+ years doing engineering of complex systems, a lot of done inside large organizations, what I see here is very troubling.
Reminds me of the scene in the "Avengers" movie. The pilot is told to get the flying carrier over water, after one of the engines fails. The pilot said that the navigational computer hasn't re-calibrated yet. Then Nick Fury states the common sense, "Is the sun rising? Turn it towards the sun and get us over water!". The implication that the pilot forgot that the sun always rises from the same direction!
I am as guiltly as any to rely on computer simulations and design theory to tell me everything is good. Sometimes real world common sense has to intervene. Like you stated, we need to get back to expecting the unknown and adding safety factors. I know for airplanes, safety should always trump cost and/or weight.
@Ken E.: You'd think that the events of 2007-8 in the financial services industry would serve as a reminder that the fact that a large company is betting a lot of money on something is no guarantee that it is reasonable or safe.
I'm not an expert on battery chemistry, and I don't claim to be. But when Sinnitt claims that the problem has been solved while acknowledging that the root cause hasn't been determined... well, I've heard that before, in other contexts. In fact, I've heard words to that effect coming out of my own mouth in the past.
And I've found, through experience, that they are usually a prelude to failure.
I know Boeing has a lot of smart people, and I hope they've got this problem under control. But Sinnett's statement doesn't inspire a lot of confidence.
The problem seem to be that they don't know that each cell is a chemical bomb which ignites when the temperature gets high enough. It supplies its own oxidizer. The cells must be kept below the ignition temperture if they short internally or contained and kept from igniting adjacent cells. Keeping oxygen out may not solve the problem. They may need thermal separators between cells and/or some cell cooling. If their real solution is to just accept some battery meltdowns but contain them to save the plane they should say so. The "failure is impossible" PR does not inspire confidence.
There was a time when engineers had a good feel for the existence of unknowns in a design and introduced safety factors to reduce the chance of failure. The Boeing battery and Carnival cruise ships suggest that blind faith in computer outputs has eroded this essential art.
You have raised the bar higher now. Leadership has slowed things down and even resulted in huge failures, like the Challenger "O" seal debcale.
I was one of the companies associated with the SRB program and everything was all based on $$$$ and savings. Well; as you are all aware Roger Boisjoly and his engineers gave compeling evidence on why not to launch; but management over rode their evidence; never tried firing an engine in such cold temperatures, so not data on how the "O"-rings would perform- Duh management 101 listen to the experts and not the Bean counters or Washington Politicos/Lobbyists.
The external tank was also an accident waiting to occur and again engineers had some good ideas, such as wrap the fuel tank with a Saran wrap type covering or place a protective burnable shield on the underbelly and wing edges so ice, frost chunks and foam would not do damage; again NO, costs too much.
As Willima stated "Kicking the Can Down The Road" is too often an acceptable risk-minimization solution utilized by Management in all types of mechanical, electrical, chemical, financial, educational, and political systems.
So the ROOT CAUSE ANALYSIS is a must not leave it up to a possible Acturial/Statistical alogorthim for RISK. FORD did on the PINTO and it cost them $1+ biilion in claims, attorney fees and fines etc at the end of the day and for what saving approximately $1.05 per fuel tank by gluing it the under body of the car, where it got ripped off in a rear end accident and spilt all of its fuel- Ford made approx 890,000 + vehicles in the Pinto range, do the math on "Kicking the Can Down The Road".
Great comment William, more people should feel like you and management should be hanging their collective heads in shame.
Mr. Sinnitt's over-confidence rather pales in comparison to that shown by the confident second guessing exibited in replies here, by people not nearly as clued in as he is about the issue. Compare air passenger flight deaths/mile to automobile deaths/mile, and this begins to sound like hysteria, which we engineers pride ouselves as free of.
No other of the engineering mistakes mentioned really has much to with this one, the only thing they have in common is hubris. Fortunately, these battery issues came to the attention of Boeng early in the program without any deaths or injuries.
I'm OK with Boeings answers and fixes. They are not betting just the lives of passengers, but also betting the entire company, their livelihoods, their reputations. I'm guessing these were tested six ways to Sunday.
Airbus took technology risks with it's early planes, and also hit some bumps. Any plane is potentially life threatening, even after thousands upon thousands of hours. One can't say that any systems are safe beyond a doubt, only that they are safe beyond reasonable doubt. So what's reasonable? Perhaps that what this discussion should be about.
Your comment is very relevant about material QC and specifications. I have worked with a number of Lithium Battery companies in the US and overseas in providing process mixing systems, all are built with 316 L SS processing parts-even though I pointed out the equipment will shed miniscule particles of the 316 l SS.
Even the BASE Materials used in the batteries are processed within steel contact surface systems, so mininscule metallic particles will always sluogh off as the equipment is used. Even the equipment I have supplied.
Remember 316 L SS is non-magnetic so cannot be removed magnetically, like 4130 or caste iron (used on roll mills-even though some are chromed).
The electrolyte is a liquid dispersion which can be filtered under pressure through an appropriate filter assy down to 0.5 microns and occasionally less for low viscosity fluids (0.02 microns). Some particles have been measured in the 2 to 8 micron range- easier to remove
It appears the electrolyte has been one of the sources of the heating occuring due to the build up of metallic particles agglomerating in sections of the cells. Where did they come from, is obvious the Base Raw Material processing and never considered a problem because no one looked deep enough to find them till these recent problems (particles from 21microns down too 0.75 microns have been observed).
Once agglomerated and held in place by a static load in each particle the battery is now prone to shorting, thus a thermal run occurs. How do they agglomerate, easy the electrolyte is a semi fluid so these particle migrate through gravity, vibration, angular tilt during flight, slight changes in internal viscosity due to heat/load-temperature and internal pressures as the battery is being cycled.
Is their a process method which can eliminate these metallic paricles, YES. But will require a total rethink and retooling from all suppliers of the base raw materials and the process mixing equipment being used to make the final battery assemblies. If these batteries are to continue as a source of power on aircraft
Just like in the electronics industry, "cleanliness is next to godliness" through each and every phase of production. Even a skin particle can ruin a semiconductor component. That why many of there process systems are specialized ceramics, coatings or mills, all the way through the operation.
Boeing have put more than 1,000 personnel on this problem and still do not have a ROOT CAUSE-whoa. Who forgot basic chemistry/engineering 101?
The sketch they have in this article does not even address the real problem and Scott you have placed your finger on it and so has Professor Don Sadoway of MIT.
They can vent for all there worth, but what about keeping it cool or cooler when such a condition arises if they are not willing to go back to the basic chemistry of the battery and clean that up first.
I mentioned above the number of Boeing personnel involved and I have spoken with a long time Boeing person who has some ideas but their are too many now on the table. Nothing at this time can distract them from getting the aircraft back into service and the above is Mike Sinnett's current answer, without a ROOT CAUSE ANLAYSIS at hand!
Maybe Boeing should ask FOR ASSISTANCE outside the company and also the Battery Manufcarurers should also do the same together with the Base Raw Material suppliers.... get clean materials and reduce any problems there and make a better containmant housing.
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