Lithium batteries in 787 may pose fire issues

[martin]

Rumours ... rumours ...

...among which "runaway battery in laptop in overhead crew rest area?"...

Solid fact: Shares dropped by 7 (later 4) %...

Martin

[Jeroen Hoppenbrouwers]

Latest rumour:

"The aircraft fire is unrelated to the batteries. This will be confirmed tomorrow in a boeing press conference. Fire is strongly believed to be as a result of galley overheat - failure of coffee heater trip switch which was left on.Burnt out much of the galley and area above causing deep damage to aft bh and rudder/elevator system. Aircraft sadly a write off - unless pride of hull loss/p.r dictates repair even if economically un-viable."

avherald.com, posted by "ba ground engineer" -- we'll see

[mabe54]

Sorry.

[Sese]

Could it have been the lithium-mangan battery of the ELT transmitter? It's right next to the spot that burned. Plus Honeywell is now officially participating in the incident investigation.

[Phil Bunch]

Here's an excerpt from a WSJ news article on the ELT transmitter theory:

http://online.wsj.com/article/SB10001424127887323848804578607910816833722.html#printMode

Investigators are examining the emergency locator transmitter on the Boeing Co. 787 as a potential cause or contributor to the fire that damaged an Ethiopian Airlines jet at Heathrow Airport last Friday, according to several people familiar with the inquiry.

The transmitter is made by Honeywell Inc. and located in the upper rear part of the 787, a location that's offering an early clue to investigators probing the incident, which came almost three months after the Dreamliner returned to commercial service following problems with its batteries.

U.K. investigators signaled over the weekend that battery problems hadn't triggered the Heathrow fire, and it remains unclear if the transmitter was the cause of the fire or a contributor to the damage of the aircraft. The device is designed to be activated in the event of a crash to help find the aircraft.



The transmitter is installed in the ceiling above the rear doors of the Dreamliner and is at the center of the larger of two areas of fuselage skin damage seen on TV footage of the affected jet.

The devices are widely used on aircraft of all sizes, and are powered by a self-contained lithium-manganese battery, which have a less volatile history than the lithium-ion versions that caused problems on 787s earlier this year.

[Phil Bunch]

Here's a link to a news article on the most recent 787 fire.  It contains a link to an official UK statement on the fire, and that statement says it appears unrelated to the primary backup lithium batteries:

http://www.businessweek.com/articles/2013-07-15/how-to-fix-a-hole-in-a-boeing-787#r=rss

The above article also discusses how one goes about repairing a composite airliner, which I found to be quite interesting.

The link to the UK statement is here:

http://www.aaib.gov.uk/cms_resources.cfm?file=/Boeing%20787-8%20ET-AOP%20Press%20Release.pdf

An interesting article on what the world's 787 pilots do when the 787 is grounded is here:

http://www.businessweek.com/articles/2013-03-14/with-boeings-787-grounded-pilots-find-other-stuff-to-do

I hadn't realized that they are usually not allowed  to switch to another aircraft type if their primary type is grounded...

[Phil Bunch]

The NY Times adds its story re the ELT being the source of the fire:

http://www.nytimes.com/2013/07/16/business/inquiry-into-787-fire-said-to-focus-on-transmitter.html?ref=todayspaper

Interesting that ground electrical power wasn't on:

--------------------------------
Here's an excerpt:

 But the battery in the transmitter is much smaller and less flammable than the other lithium batteries, which can supply power when the plane is on the ground and provide backup power for the flight systems when it is in the air. Those batteries include cobalt, which is more volatile than manganese, a substance used in some electric cars and laptops. The larger cobalt batteries are also rechargeable, while the one in the emergency transmitter is not.

Industry officials have said that the Ethiopian jet was connected to a ground power source. But the airline has said that the power was not on when the fire started.

Hans J. Weber, the president of Tecop International, an aviation consultancy in San Diego, said that if the battery in the transmitter was not rechargeable, it was hard to see how it could have started the fire. "It's a passive device waiting to be activated in an accident," he said.

[Jeroen Hoppenbrouwers]

"It's a passive device waiting to be activated in an accident," he said.

Impatient device, eh?    :twisted:

[Phil Bunch]

Another update, this time with the British authorities urging the American authorities to disconnect the offending ELT.  

http://www.nytimes.com/2013/07/19/business/investigators-point-to-transmitter-battery-in-787-fire.html?ref=todayspaper&pagewanted=all&pagewanted=print

Here's an excerpt:

 After British authorities urged American regulators to order airlines to disconnect the batteries in the emergency transmitters on Boeing 787s, the Federal Aviation Administration took a more measured approach, saying that it would review the matter.

Britain's Air Accidents Investigation Branch, which also called for a broader safety review of similar devices in thousands of other passenger jets, made its recommendations on Thursday after finding signs of disruption in the battery cells of an emergency transmitter on a 787 Dreamliner that caught fire while parked at Heathrow Airport last week.

Most passenger jets do not have fire suppressant systems near the devices, which send out a plane's location after a crash. If a fire occurred in flight, the British investigators said, "it could pose a significant safety concern and raise challenges for the cabin crew."



 Although Britain is still investigating the cause of the fire at Heathrow, Boeing said it supported the recommendations as "reasonable precautionary measures." Honeywell Aerospace, which makes the 6.6-pound transmitters on the 787, said the proposals were "prudent," though it remained "premature to jump to conclusions" about the cause of the fire.

Thomson Airways in England said it would remove the batteries from its 787s. Other carriers that use similar transmitters, from major airlines to corporate jets, were left to decide whether it was safe to keep using them. The F.A.A. decided it needed more time to evaluate the proposals, which could conceivably lead to the removal of the batteries or the transmitters from most of the planes made by Boeing, Airbus and the smaller companies that make regional and business jets.

Federal officials said the lack of definitive evidence about the cause of the fire — and the fact that none of the transmitters had been known to cause a fire in more than 50 million flight hours — suggested they should take more time in reviewing the matter.



 The report said no other systems in that area would have contained enough stored energy to start a fire with the plane's basic power system turned off. The transmitter, which could broadcast distress signals for many hours after a crash, is designed to operate independently of the jet's power system.

Still, the investigators expressed surprise that the battery could have caught fire, noting that the manufacturer of the transmitter, Honeywell Aerospace, had produced 6,000 of the transmitters for a wide range of aircraft since 2005, including some Airbus planes, without similar incidents. Honeywell and other manufacturers also make similar devices for thousands of other commercial and business jets.



Investigators said a hand-held extinguisher did not stop the fire, and the firefighters had to knock down a ceiling panel to get to an upper compartment where the transmitter was. While the firefighters were then able to put out the blaze, the fire was so intense that it damaged the plane's carbon-composite structure in that area and caused the exterior paint to blister and peel.

------------------------------------------

I personally hate to see institutions make evidence-free changes in an attempt to quickly fix something that may have gone wrong.  There's an old aphorism:  "If you haven't got the time to fix it correctly, will you have the time to fix it over and over?"

Is it really credible that the ELT spontaneously burned with such intensity?  Perhaps the world's high-tech batteries have been taken over by supernatural forces?!

[mabe54]

Signs of the times we live in. PR reactions supersede sound engineering practices, common sense. careful analysis, science and everything else.

 :x

Cheers,

[torrence]

Re above:  I seem to remember reports of iPhones getting way hot also (mine still gets really uncomfortably warm at time, particularly at low battery charge levels).  Would be interesting if the whole "pack more and more energy density into smaller and lighter devices" problem has some limits for a lot of things.  Moore's law can't apply indefinitely to all parts of these systems at the same time!  Maybe this will spark a new wave of spontaneous human combustion stories in the tabloids.

Cheers,
Torrence

Edit - some of these reports imply that these Honeywell ELTs are in lots and lots of ships other than 787's.  Maybe Boeing just got unlucky?  Unless they insisted on some mods ...
T

[Jeroen Hoppenbrouwers]

787 mods.

Being the Electric Jet, one of the things that a 787 does differently is the circuit breaker stuff. The 787 does not have bi-metal CBs on the flight deck. Instead, the actual breakers are remote, and as far as I know solid-state. They are linked to pseudo-breakers on the flight deck so pilots can still selectively disable systems and see what popped due to overload.

One of the obvious things in which a solid-state breaker is different from a bi-metal breaker is response time. Classic avionics that draw 1 amp in operation may easily draw 10 amps for 10 ms during powerup (current inrush) and a bi-metal breaker does not even blink at this. However, a solid-state breaker trips after 1 ms into the 10 amps inrush.

We had to fix this for our Iridium satcom unit which, we are proud to say, flew on the 787 test fleet as a backup communication device (FANS and all).

It may be that this kind of fix (diodes and resistors over the main power capacitors) has screwed up something stupid in the ELT. A blind guess, but the 787 does require different equipment than any other jet at this moment.


Hoppie

[Phil Bunch]

Another update from the NY Times:

http://www.nytimes.com/2013/07/20/business/boeing-787-inquiry-zeroes-in-on-transmitters-wire.html?ref=todayspaper

This article is partially composed of text from the previous NY Times article I linked, above. Below are  some excerpts - I hope I didn't include any duplicate text:

-----------------------------------------------------------------------

 The Federal Aviation Administration said on Friday that it would order inspections of the wiring in emergency transmitters on Boeing 787s as it continues to narrow the search for what caused a fire on one of the jets last week at London's Heathrow Airport.

Safety investigators are examining whether a pinched wire on a harness connecting a battery to the transmitter caused or helped spread the fire. They also want to check the transmitters' battery for signs of unusual heating or moisture.

While the agency prepares the order over the next few days, Boeing plans to instruct all 13 airlines that use the Dreamliner to either inspect or remove the transmitters, which send out a plane's location after a crash.



 The 787's cabin maintains a higher humidity level than other jets to increase passenger comfort. One theory is that the humidity could have created condensation that caused a short circuit in the battery or its wiring.

Another concern is that the composite skin absorbs more heat from the sun than the aluminum on other planes. That has prompted questions about whether the battery in the transmitter could have been degraded by excessive heat from the skin.

But battery experts said that barring a flaw in the battery's construction, the transmitter is sealed so tightly that neither moisture nor heat was likely to cause a short circuit. "I can't really subscribe to either one of those," said Ralph J. Brodd, a battery consultant in Henderson, Nev.

[Jeroen Hoppenbrouwers]

http://www.skybrary.aero/index.php/B788,_London_Heathrow_UK,_2013_%28FIRE_AW%29

[Sese]

So the FAA released their AD. Battery and cable checks for all ELTs onboard US 787.
ANA said today it found two minor irregularities with ELT-cable insulations after checks and exchanged two of their 787-ELTs.

PS: United found another one

[mabe54]

http://www.skybrary.aero/bookshelf/books/2078.pdf

Like carrying grenades with loosely and easily dropping pins.

What a nightmare.

Cheers,

[mabe54]

http://au.news.yahoo.com/thewest/a/-/world/18165788/qatar-grounds-a-787-as-glitches-pile-up-on-boeing-jet/

Cheers,

[Jeroen D]

Still not out of the woods yet:

http://edition.cnn.com/2014/01/14/travel/787-dreamliner/index.html?hpt=hp_t1

http://avherald.com/h?article=45c377c5&opt=0

Jeroen

[Sese]

What is practically happening, if a 787 should lose it's main battery inflight? What systems and functions are affected and what is left please?