787 battery fix approved Boeing's beleaguered 787 is a little closer to flying again after the USA's Federal Aviation Administration (FAA). approved the plane-makers new battery system plans. The 787 was grounded earlier this year after battery packs on two craft overheated and produced lots of smoke. Boeing revealed the details of the two incidents …
...but there's no way this little black duck will be getting on a B787 for at least a year or so.
I do not trust Boeing's 'fire box' solution to their as-yet-unexplained battery fires as it does nothing to explain how the last two 'non-fires' happened. All it does is (hopefully) contain any future fire. A couple of highly publicised flights in which the batteries didn't catch fire does not solve the problem.
This will only be ironed out when Boeing / Yuasa / ??? publish why the batteries reacted in the way they did. Anything else is a band aid solution (Bob Geldof not included).
Anon due to aviation involvement.
The thing is that the rules allow things to fail in aircraft. The design of the systems says that the failure must be contained, there must be redundancy in the case of critical items (think flight control computer), and that the failure must not proagate to the redundant systems (and often requires it to not propagate to other sub-systems. There are often failures that might even be traced to a single component, but even then the root cause of that component failure is never known. As long as the failure is graceful (contained with no side-effects) then OK. Change the LRU (Line Replaceable Unit) and the aircraft goes back in service.
In this case, the solution seems to be to ensure that the failure in one cell is much less likely to propagate to another cell. What's more, the new enclosure is supposed to contain any failure to within the battery. In my book that's OK.
Yes, but in this case the failure was contained within a little room that also contained the electronic make-it-go boxes for all the computerized whizzbanggery that makes the aeroplane fly.
*I'd* be happier if said batteries were contained in slide mounts that allowed them to be individually ejected when they start fizzing, like they do with a Federation Starship's Fizzy Warp Core.
And what is apparently not being mentioned as much in the mainstream press (haven't checked more aviation centric sites) is that the FAA may limit the ETOPS (Engines Turn Or Passengers Swim, sorry, Extended Twin Operations) rating for the 787, which also reduces the routes it is viable for (or makes the airlines fly way longer routes to stay within the ETOPS rating). That means that the 787 may not be the dream plane that many airlines are hoping for, unless it can keep it's ETOPS 180 rating that the B777/A330 enjoys.
And until there is a full, and publicly published report on the CAUSE of the failures of the battery, I agree. The solution just prevents the batteries from (HOPEFULLY) making a mess. It doesn't stop the problem.
Airline cabin fittings (seats, etc) are required to be tested to prove they are either fire resistant or do not contribute to a fire. Unless Boeing deliberately triggered a thermal issue in the batteries during the test flights, the solution ISN'T TESTED TO ADDRESS THE PROBLEM.
I would like an explanation as to how the engineering change would resolve the safety problems. What was the theory behind the failure? What was the root cause of the failure? How does the change mitigate the failure?
Not going to get me on one of them for a very long time...
Where I live fireplaces aren't allowed, unless they're pre-existing. Perhaps I can justify adding one by explaining that they're actually just "near-fireplaces"?
I add newspaper, and a few small sticks, throw a match in and watch as the paper and sticks overheat and produce lots of smoke. Then I add some bigger sticks which overheat and produce lots of smoke, followed by a large log, which gradually overheats and produces lots of smoke.
I'll need a chimney of course, but that's just so I can perform an "emergency venting procedure".
1) Cut hole directly through fuselage directly above battery compartment.
2) Line with bricks (components labelled a1), using mortar (bag b1, add water*).
3 )At exit point on fuselage exterior, use ornate bricks (component a2) to raise above fuselage line.
4) Finally, mount chimney pots (component a3) using remaining mortar (bag b1).
In use, do not be alarmed by smoke rising through the conduit. This is a design feature intended to add an 'old world' aesthetic. If, however, flames are seen, use enclosed bucket* (component a4) to extinguish, otherwise flaming death crash may ensue (please refer to Bible - component a5).
*Water not included.
p445 Insert: "7b During normal operation some smoke and/or flames may be seen coming from the battery pack. This is perfectly safe and is not a cause for concern.
If the problem persists the pilots should reduce altitude and land the aircraft. At this point the Captain may wish to inform the passengers of the aircraft's status, but phrases such as 'the plane's on fire' or 'we're all going to die' should be avoided as they might cause alarm.
If the aircraft is already descending the pilots need take no further action as the aircraft will automatically stop when it reaches the ground."
The problem is that they used the highest energy (LiCoO2) battery chemistry, which is prone to catastrophic disassembly with flames in the event of a microscopic tear in the separator, minute gaps in the carbon or other unforeseen event such as separator ionisation and breakdown from cosmic rays or TGF's.
Even X-raying the cells post manufacture won't show up this sort of damage.
It might not appear for hundreds of cycles so even extended soak testing wouldn't show this.
One way to potentially detect imminent failure would be to use ultrasound, if areas of the carbon or LiCoO2 are delaminating or otherwise changing shape then transmission of sound waves through the cell would show a localised change compared to the reference from original manufacture.
A similar method is already used to detect forming cracks in metallic aircraft parts.
As someone who did research in ultrasonics, I'd suggest that the use of enough energy at the right frequencies to get a signature capable of detecting changes in a battery pack might itself trigger those changes. Unlike aircraft wings and turbine blades, batteries are not designed on the basis that if they are affected by ultrasonic inspection, they failed already.
If we're talking chimneys, perhaps the 787 may save yet more fuel if the batteries are installed in a wood-burning stove somewhere in the middle of the cabin, warming the air without wasting power from the engines.
An wood burning stove is, of course, preferential to an open fire, as it gets through fewer burning batteries per hour.
" The FAA will require airlines that operate the 787 to install containment and venting systems for the main and auxiliary system batteries, and to replace the batteries and their chargers with modified components."
... I guess nobody read the "replace the batteries and their chargers with modified components" bit, huh?
That's fix the problem *and* box the subsystem in case it's a tricksy little blighter than has other problems.
Considering that none of the published reports investigating the existing battery incidents on B787s has provided a cause for the incidents, the modifications are no more than further protective measures. Only once the root cause is found for the existing incidents (and any future ones) can the charging circuits be replaced/updated to avoid future problems.
Unfortunately the root cause for lithium battery failure is "yes, they sometimes do that".
A battery is either a bag of chemicals with more or less reliable support systems, or something rather large with components that can be examined in place. There is not room for the latter on an aircraft.
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