FAA Grounds 787s [Archive] - Page 5

deptrai

26th Feb 2013, 13:50

Is there any specific technical requirement for LiIon-batteries to be used onboard the dreamliner in any case? Anything that technically prevents other battery types from being used? Not speaking about time, cost and weight but functional hard needs. Let them be heavier and bulkier but that can't be the reason to not consider NiCads?

Yes. The answer is hidden somewhere in this long thread - the discharge rate, which is needed for the electric brakes, and for APU start.

quoting Mike Sinnet, VP of Engineering and chief project engineer for the 787:

"The driving factor in our design was really the ability of the battery to discharge a large amount of energy in a very short period of time. And this was required for two different functions at an airplane level.

One was for starting the auxiliary power unit and the other was for being able to apply braking to the airplane in the event that all other power sources in the airplane were lost. The 787 braking system is an electrical braking system. It uses electric power to stop the airplane. And we need to be able to stop the airplane, perform a rejected take off on purely battery power without any other power source at all. So those two things, electric braking on the main battery, APU start on the APU battery. Those are the two things that drove us to considering lithium ion batteries as the best power source for batteries in the design of the 787."

Boeing set up a more detailed website about the 787 here, which explain the systems "in laymans's terms":

787 Electrical System - Boeing 787 Updates (http://787updates.newairplane.com/787-Electrical-Systems/787-Electrical-System)

Batteries and Advanced Airplanes - Boeing 787 Updates (http://787updates.newairplane.com/787-Electrical-Systems/Batteries-and-Advanced-Airplanes)

Are there any other applications of the LVP65 cell on commercial aircraft or is this new territory for the manufacturer?

None on commercial aircraft.

Boeing has anticipated this question...and proactively mentions that li-ion batteries (but not necessarily that cell) are used in (aero)space engineering, the Boeing 702 communications satellite, and the Mars Rover :8

Kerosene Kraut

26th Feb 2013, 14:04

So if the wrong battery smolders you'll lose your final backup-brake even with the hotbox system?

deptrai

26th Feb 2013, 14:08

Yes. (There's 2 also generators per engine, 2 in the APU, and the RAT, but clearly the idea was that the battery would be the "last" backup and able to handle braking). The APU battery isn't on Boeing's Master MEL, and the APU will shut down without it; so in a worst-case catastrophic scenario, with no APU, and a double bird strike, assuming the RAT will be of very limited to no help for braking, you don't want the main battery to smolder at the same time. Highly unlikely, but I'm sure someone is calculating probabilities :E

Momoe

26th Feb 2013, 14:08

If two of the main drivers for the battery are APU start and brakes, why wasn't air considered?

I know the spec. for APU starts required the capability of multiple re-starts up to and including service ceiling (43k) but multiple could be any number between 3 and infinity.

There is also the possibility of having a hybrid braking system, electric on the front axle of the main gear and pneumatic on the rear axle.
Accepted, there are potential weight penalties but you've also introduced additional redundancy to the braking system

sb_sfo

26th Feb 2013, 14:19

You'll always be able to open the side window and stick your arm in the slipstream. Oh, wait, the windows don't openhttp://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/boohoo.gif

inetdog

26th Feb 2013, 15:48

Ex Cargo Clown said:
I have a feeling that the load demands and recharge rates of NiCd wouldn't be enough for the elec system. Quite why they went with LiCo rather than LiMn is beyond me. Going to try and short an LiMn one this afternoon. (Don't try this at home kiddies )
Why stop at LiMn? LiFePO4 is even more inherently safe and has lots of accumulated use experience in abusive situations. It does not have as good an energy density or internal resistance, but both are better than for NiCd.

BARKINGMAD

26th Feb 2013, 19:37

There's a lot of lovely interesting data and tech details here on batteries which do and some which don't.

I reiterate my question in the referenced post, where was the experinced old lag from the line who is one of the guys/gals who have to daily get airborne and risk their asses with this kit?!

You can argue all you want about cells and loads and fireproof boxes and other protective devices, but the opinion of posters, some of whom I suspect are aircrew/pax, seems to be "no gov, go back to the drawing board, I refuse to travel in it!".

Maybe those from the design team, if they're reading this thread, would like to give us a breakdown of the qualifications of those on the team, and whether it included an INDEPENDANT line pilot who was NOT employed or otherwise beholden to the company.

Eagerly awaiting this info, but without much hope.

In 42 years in military and civil aviation, I have met ONE pilot who claimed to have been invited to a manufacturers facility, in order to play with a bench version of the latest widget being proposed and to offer feedback.

Maybe I oughta get out more, but I'm still busy reading others' incident/accident reports so's I can better detect early when the holes in the cheese start to line up!

Are there any other airframe drivers out there who agree with this opinion/query? :ugh:

TURIN

26th Feb 2013, 20:24

If two of the main drivers for the battery are APU start and brakes, why wasn't air considered?

Dreamliner philosophy. No Pneumatics.

Speed of Sound

26th Feb 2013, 20:54

I'm just waiting to see if the firebox solution, once signed off by the FAA, doesn't become the long term fix.

That is why this whole 'temporary certification' thing is a complete fantasy.

The only way to avoid what EEngr is predicting from becoming fact, is if the temporary certification comes with a time limit, say four months.

If the four months pass and Boeing tell the FAA they still don't have a permanent solution, what happens then? If the fleet is once again grounded then Boeing can quite rightly turn round to the FAA and say "You said our plane was safe to fly yesterday. Why isn't the exact same plane safe to fly today?"

I'm sorry but I can only see this happening if Boeing do have a permanent fix and are given time to dot the 'i's and cross the 't's. This 'put it in a box while we work on the problem' is a non-starter. :ugh:

kilomikedelta

26th Feb 2013, 21:02

Turin: 'Philosophy' implies altruism. I think 'mission statement' is the current corporate term to attract investors.

FlightPathOBN

26th Feb 2013, 21:30

Why stop at LiMn? LiFePO4 is even more inherently safe and has lots of accumulated use experience in abusive situations.

They switched to Lithium Cobalt Oxide in the later models of the 787....

Lithium cobalt oxide - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Lithium_cobalt_oxide)

Walnut

26th Feb 2013, 21:31

The truth is slowly coming out. Boeing have admitted to circa 150 early battery changes, mostly I suspect as they were down on power. If you recall there was an incident just before the battery fire problems of a braking problem, low backup power maybe? Also other electrical problems with refueling valves, again would these have been caused by errant battery power problems? as refueling is often done with out the full electrical system being powered. As it would be impossible to retrofit the brakes with a hydraulic accumulator as fitted to other a/c types, maybe the way ahead is to double up on more reliable older style batteries. Yes it would add weight, but at least the a/c would be flying.

FlightPathOBN

26th Feb 2013, 21:35

Walnut,

If you can believe the Boeing spec...the batteries are 32V 150A...

http://787updates.newairplane.com/Boeing787Updates/media/Boeing787Updates/Batteries%20and%20Advanced%20Aircraft/newBatteries_large.jpg?width=900&height=674&ext=.jpg
They state you can only get 16A from NiCd...

TURIN

26th Feb 2013, 22:59

Walnut.
You are barking up the wrong tree.
Normal brakes do not need backup battery.
Refuelling is almost always done with full system power.
Lets not build a conspiracy eh? There's enough around already.

FlightPathOBN

27th Feb 2013, 00:56

SEATTLE (Reuters) - The Federal Aviation Administration said it is not close to approving test flights of Boeing's 787 Dreamliner with a proposed fix for the plane's troubled batteries, denying news reports that such tests could start as early as next week.
"Reports that we are close to allowing 787 test flights are completely inaccurate," spokeswoman Laura Brown said on Tuesday in an email to Reuters.

http://finance.yahoo.com/news/reports-boeing-787-test-flights-001132267.html?desktop_view_default=true

EEngr

27th Feb 2013, 02:36

quoting Mike Sinnet, VP of Engineering and chief project engineer for the 787:

The driving factor in our design was really the ability of the battery to discharge a large amount of energy in a very short period of time. And this was required for two different functions at an airplane level.

One was for starting the auxiliary power unit and the other was for being able to apply braking to the airplane in the event that all other power sources in the airplane were lost. The 787 braking system is an electrical braking system.Which function (backup braking or APU start) places the greater demand on the battery system? I'll venture a guess and say its the APU start. That has been possible with NiCad technology for quite some time. And given the variable frequency drive motor/generator, I'd guess that the old school DC starters placed more strain on a battery than these LiON batteries will see.

The brakes, while critical, don't appear to have the same demand as APU start. There are a few pics of the system here:

Messier-Bugatti-Dowty (http://www.safranmbd.com/activites/programmes-majeurs/article/boeing-787-dreamliner)

While there are no electrical demand specs, one can size up the electrical components (motors, connectors and wire bundles) and make some guesses about demand.

So falling back to a NiCad system may not be so far fetched as Boeing would like people to think. The main problem will be building up a 32V NiCad battery assembly and certifying it with a 32V charger. This would be prefferable to redesigning and recertifying the 787 with a 24V DC system (to use off the shelf battery systems). But its still possible.

deptrai

27th Feb 2013, 03:06

some more here: http://www.goodrich.com/gr-ext-templating/images/Goodrich%20Content/Business%20Content/Aircraft%20Wheels%20and%20Brakes/Products/Literature%20Listing/787%20Fact%20Sheet.pdf

and here, Patent US6402259 - Electromechanical braking system with power distribution and redundancy (http://www.google.com/patents?id=Pd8JAAAAEBAJ&pg=PA5&hl=en&source=gbs_selected_pages&cad=4#v=onepage&q&f=false) including a description of the emergency mode

Kerosene Kraut

27th Feb 2013, 07:37

If Boeing would finally change the battery type and recertify the modified system. How long would this take?

Walnut

27th Feb 2013, 07:43

Posting 1038 by "deptrai" shows how complex an electro mechanical braking system can be. It is I suspect a heavy power user, so instead of the Hot battery bus providing power to fire extinquishers & P1 standby instruments etc, all of which use little power, this backup source has to be meaty.
It would be interesting to know why the a/c to date has suffered circa 150 battery replacements? Low voltage?? In a way this is a more serious problem than the two fire instances, since no sane pilot would accept an a/c without ultimate back up power.
I can see the potential for a complete redesign of this part of the electrical system.

Golf-Sierra

27th Feb 2013, 08:44

The brakes, while critical, don't appear to have the same demand as APU start.

I wouldn't underestimate that.

4 actuators x 8 wheels = 32 actuators. 150A /32 = that's just 4.68 A per actuator.

green granite

27th Feb 2013, 09:15

cockney steve

27th Feb 2013, 09:54

@GolfSierra...on the face of it, -yes you'd think so,,,,but there's a gear-train which multiplies the mechanical effort, The amount of pad-travel is extremely small and, as I postulated a while back, the system is electronically controlled to reflect pedal-pressure.

Effectively, each unit is an electrically powered jack--it only needs max. power to press the pads harder,a small burst of current ,then the thing holds itself in position....I'll grant that an instantaneous peak load MIGHT be quite high ,upon initial application,but I think this line is another red-herring.

Multiple APU starts?....cobblers! it has to cool for 30 minutes otherwise the Turbine-shaft apparently distorts(bends)S0, fire it up and the first thing it does is recharge it's own battery....well. that's what sound practice says it SHOULD do,,,,but the demonstrated masters of fudge and kludge may have a different view.

I'm just an oik, I don't get to gamble/fritter billions of shareholders' money on projects that appear to have a large input of hubris without the applied expertise behind it.

A triumph of marketing over reality?

One thing's for certain, Buyers who feel , justifiably, they've been stitched-up with a very expensive ,short -term Hangar-queen, and have to answer for their own misplaced faith, -should be, and probably are, royally p155ed-off. It'll take more than a lavish dinner and floor-show to placate them.

TURIN

27th Feb 2013, 10:13

Presumably once the APU is running and or ground power is on, then the batteries are no longer needed, except in an emergency, and could be isolated.
So why not treat them as primary cells and do a swap-out before flight and have the charging system disconnected? The batteries could then be recharged under controlled conditions on the ground and inspected before being used.

That is of course presuming the problem is only due to charging.

I'm probably missing something as it seems too simple a solution, albeit a temporary one.

Can you imagine the logistics nightmare that would cause.
Servicable batteries required at ALL line stations. Maintenance time to change the battery. These a/c get turned around in less than 90 mins. Disconnecting the power for 30 mins while you change the batteries would kill that. How many function checks would be required after the swap to ensure the system will work as required.
Then there is the problem of transporting hundreds of batteries all over the globe.
Alternatively you have charging workshops on every line station.

I can't see the airlines wanting to carry the cost of any of that.

Multiple APU starts?....cobblers! it has to cool for 30 minutes otherwise the Turbine-shaft apparently distorts(bends)S0, fire it up and the first thing it does is recharge it's own battery....well. that's what sound practice says it SHOULD do,,,,but the demonstrated masters of fudge and kludge may have a different view.

That 30 min cool down period is a temporary arrangement. A work around. It was certainly not the intention from the manufacturer. It became apparent during service. A permenant fix to the rotor bow will appear in good time.

I take the point though. A Nicad battery would suffice. It has for other types so why not this? Commonality of parts is the only reason I can think of.

Oh, and saving weight. :rolleyes:

green granite

27th Feb 2013, 11:14

These a/c get turned around in less than 90 mins. Disconnecting the power for 30 mins while you change the batteries would kill that.

1) If the battery is isolated the A/C does not need to be powered down at all.

2)The battery would only need changing if used, capacity indicators are not rocket science.

Then there is the problem of transporting hundreds of batteries all over the globe.
Alternatively you have charging workshops on every line station.
I can't see the airlines wanting to carry the cost of any of that.

Cheaper for Boeing to pay for that than having them as expensive ornaments twiddling their wheels in a hangar and it would take some of the pressure off of providing a fix. That way a proper engineered solution could be devised and tested.

Ex Cargo Clown

27th Feb 2013, 11:28

Well my LiMn mission was interesting tried to short it, just wouldn't go, twice it's rated ampage as well. So set it on fire with diethyl ether, only thing that burnt was the plastic and solvent. Ordered some LiFePO4 ones to give them a go. But LiCo? Why?

Speed of Sound

27th Feb 2013, 12:13

just wouldn't go,

And that is a problem Boeing will have if this ludicrous 'stronger box' solution is even considered by the FAA.

It is quite easy to force a problem by overcharging a battery or to try to charge a seriously depleted one but to force a thermal runaway due to an internal short circuit will be almost impossible to do short of manufacturing a faulty battery or charge/recharge cycling it until dendrite growth becomes a problem.

This all has to be done in flight too so that thermal effects on the rest of the electronics bay can be measured as well as the efficiency of any venting system.

The 'bigger, stronger blue box' solution may be a quick fix but I can't see proper certification of it being particularly quick. An alternative would be a mathematical extrapolation of the worst-case scenario based on the total energy inside the box but I really don't think anything short of a battery on fire on an actual flight will satisfy the FAA this time round.

toffeez

27th Feb 2013, 12:51

I think the test should be: fly around for 180 minutes after a fire and/or explosion is confirmed to have occurred inside the steel "safety box".

Any volunteers?

Hi_Tech

27th Feb 2013, 13:22

The following is a bit long, but if you are a pilot or engineer you might appreciate this discussion.
Design decisions are not given out by aircraft manufacturers. But if you know complete engineering details of several aircraft, like in my case, one can see through the tangle and guess what are the problems Boeing is facing. I am not a design engineer, but one who was trained and worked on the last 5 Boeing jets produced and the last 5 airbus including A380.
On all aircraft till B787 design, there are three prime sources of motive power.
1. Electric. 2. Pneumatic. 3. Hydraulic.
To understand Boeing's problem now one has to know how the motive powers are derived on all previous aircraft.
Electric generators are on the engines and APU. With emergency power from batteries and RAT, which has a small generator the size of a pineapple, 10 KVA capacity on B787. B787 has normal generating capacity of 1450 KW.
Pneumatic is sourced from engine bleed or (if running)APU bleed below a certain altitude about 25000 ft.
Bleed air from APU, when on ground, is used to start engines. After an aircraft lands from a flight, as engine bleed is still available, it is used to start APU as in B777.
Hydraulic pumps are driven by engine, or electrically driven, or in the case of Boeing 777 and 747 bleed air driven during high demand.
When Boeing designed B787, which they called is a game changing design, they took a decision to do away with bleed air system and depend on the electrics and hydraulics only for motive power source. They called it one of the features of their game changing design. But one still needs compressed air for air-conditioning and pressurizing the aircraft. So they have these two large electrically driven compressors that require 270V DC power.
Another decision was to have electric brakes instead of hydraulic brakes. A questionable choice even if saves a few kilos. This required a large battery power for emergency brakes if you have total power failure before landing. There are 8 brakes, and each brake with 4 motors driving worm gears. So you are talking about 32 motors and associated electronics to be driven by battery. (This condition is rare, but it has happened on this plane once during a test flight - Laredo, Texas incident).
But doing away with bleed air is at the heart of the current problems with this design where there is very little room left for maneuver. Engines and APU can only be started with electric starters for which they use the same 3 phase generators, that normally supply the power the aircraft. Theyare driven as starter supplying power from available sources.
Let me give an emergency situations where there is a total power failure on B777 and B787 at cruise altitude of 40,000 ft.
On a Boeing 777 the bleed air from the engines is still available, (Bleed valves stay open when power is removed), and this is used to automatically start the APU through a pneumatic starter. This source is unlimited unlike a battery with a fixed charge. Bleed air is also available for pressurization of aircraft, so the crew, if they are 40,000 ft, need not worry about pressurization, and when APU starts, power is also restored. Crew have to deal with only the electrical failure during this critical period.

On B787, when electrical power fails, they have the additional emergency of pressurization stopping as the compressors that supply air would shut down.
So they have to quickly get the APU started to restore the electric power, using of course the battery. This battery can give 2 start attempts. APUs are traditionally difficult to start at high altitude. So if there is a delay crew will face the additional emergency of diving to a lower altitude to avoid a low cabin pressure situation, while you have a pineapple size generator on RAT powering this all electric plane.
As Boeing has done away with DC starter for APU (unlike in all older airplanes), they require a power conversion circuit to convert the 30V DC power from battery to 3 phase 235 V AC power to start the APU. That could explain why you need all the power drawing capacity for the APU battery.
It may not be easy to find a Ni-Cad battery to supply 150 A. They will need 2 batteries in parallel to supply that current.
Another draw back of doing away with bleed air is engine starting. If APU is not available for any reason, they require ground power. This is only available as 3 phase 115V at all airports. This has to be converted to 235V AC 3 phase to start engines using again a power converter on airplane.
Then the air compressors require 270V DC power, which is obtained using another large power conversion. This 270 V DC is also required to drive the high demand electric hydraulic pumps.
These power conversions generate heat and these panels that are located in the middle of the aircraft (Approximately below the first row of economy seats on ANA), are cooled using 2 large refrigeration units. In the middle of this power center is the suspect APU battery. So if this goes up in smoke one can expect a total power failure on this aircraft.
After seeing these problems, I doubt if we will ever see an all electric design in future. After all, doing away with bleed air has saved only 2% fuel, the figure many in the industry are already questioning. Is it worth the trouble?

Annex14

27th Feb 2013, 13:23

To start with: I am not a battery specialist - at it´s best a thoughtful user ! I only have two 36 V 10,5 Ah battery packs - LiFe4Po of course not these potential life fire bombs types.
However if one looks at that post # 1034 picture of the B787 battery and the attached text something springs in my mind.

Yuasu says in it´s data sheet about the LVP 65 battery that it runs at 3,7 V and 65 Ah per cell. The picture shows clearly the repeatedly mentioned number of 8 cells connected in line NOT parallel. If my little mathematics are not completely gone with the years 8 x 3,7 = 29,6 V !! So how can they claim in the data under that picture that the battery delivers 32 V ???

Furthermore usually these LiIon batteries should be discharged only up to - so called 2 C . That would be in the case of the Yuasu cells - having 65 Ah a max of 130 Ah - not 150 Ah !! for a max period of time of 30 min. There is of course the possibility to discharge at higher rates than 2 C but what I´ve read about that indicates, the higher the discharge rate the hotter the pack gets and the bigger the possibility of battery "problem" become !!

Keep that in mind and look at the dense packing of the cells and simply imagine how hot it might become in the core with no obvious cooling installation at work at all !! if there is is really pulled up to 150 Ah.

There is a website under Basic to Advanced Battery Information from Battery University (http://www.batteryuniversity.com) that has some very interesting facts listed about the different types of batteries. One of these facts they cite is - if an LiIon battery was discharged too low in Volts remaining and an attempt is started to charge it with the normal charging installation it might end up with a shunt and short in the cells with all unwanted consequences.

Since all of this is simple traceable knowledge the more one wonders how in heaven such a fine product - as the B 787 obviously is - was set in such a jeopardy ??

ionagh

27th Feb 2013, 13:44

The cells are rated at 65Ah minimum and 75Ah nominal.
The discharge is rated to 5C so 2C would have a nominal value of 150A.

The 4V per cell is the fully charged value without load.
So yes they are 32V / 150Amp nominal batteries.

lomapaseo

27th Feb 2013, 14:03

I think the test should be: fly around for 180 minutes after a fire and/or explosion is confirmed to have occurred inside the steel "safety box".

Any volunteers?

I'm willing to do it with engines every day, so I'm willing to do it with their safety boxes

bacp

27th Feb 2013, 14:11

HiTech, I have no idea if your analysis is totally correct, but it is very well written with a logical conclusion.
I don't think I'll be queuing up for a 787 Rating quite yet!

ionagh

27th Feb 2013, 14:34

"It may not be easy to find a Ni-Cad battery to supply 150 A."

The battery would feed an inverter circuit to convert it to 235V 3phase AC.
So you replace a 32V 150A battery with a 160V 30A NiCd type.
Have to redesign the inverter for a higher DC supply.

gcal

27th Feb 2013, 14:50

You can talk about the differing batteries until you are blue in the face but most pilots just know that when they do a certain thing, a certain thing happens.
They are not technicians who are versed in all the ins and outs of the various systems.
They want something that does what it says on the box and doesn't introduce too many wobblies into it.
Being of the old school I'd find it hard to adapt to a cockpit that didn't have opening windows! Have I missed something or has this aircraft not got those?
If not then a large part of design philosophy seems to have gone wildly astray.

sb_sfo

27th Feb 2013, 16:33

No open window.

grebllaw123d

27th Feb 2013, 16:36

gcal,

The cockpit of the B787 does not have any opening windows, but an escape hatch in the roof.

Exactly the same arrangement can be found on the B747 and on other aircraft types, for example ATR42/72 and Bombardier Q400.

In other words, this arrangement is not a new design philosophy.

poorjohn

27th Feb 2013, 16:55

http://www.s399157097.onlinehome.us/PDFS/BoeingPR_06_12_2005.pdf
Note from this 2005 document that Thales says they selected the battery - of course they might have had guidance from their customer.

In 2005 LiCo may well have been the best "proven" technology, and having made that choice, the aerospace industry does not lightly change its path. There is so much "process" involved - drawings, procedures, manuals, ICDs (Interface Control Documents) - that even after two fires and an OAG fleet the best way forward is still to leave everything as unchanged as possible, and put a steel box around it.

In the 80's and 90's we joked about paperwork, saying we couldn't launch until the weight of the paperwork equaled the weight of the vehicle. Those were the good old days. (We also joked that a camel was a horse developed by a committee. Today meeting-rooms full of brain-deadened team players are busily turning out camel after camel.)

inetdog

27th Feb 2013, 17:45

poorjohn said:
(We also joked that a camel was a horse developed by a committee. Today meeting-rooms full of brain-deadened team players are busily turning out camel after camel.)
We also would describe an egregiously bad piece of engineering as developed by a committee of camels.
I don't think that the battery system has risen to that level yet, but I think a good attempt is being made.

CONF iture

27th Feb 2013, 18:59

In echo to the post from Hi_Tech (http://www.pprune.org/7717495-post1049.html) :

Flightglobal - Leahy questions 787’s heavy reliance on electrical power (http://www.flightglobal.com/news/articles/leahy-questions-787s-heavy-reliance-on-electrical-power-382535/)

FERetd

27th Feb 2013, 20:42

lomapaseo Quote:-"I'm willing to do it with engines every day, so I'm willing to do it with their safety boxes"

Off you go then, Chuck.

I think that you will find that those engines under your wings are a little more tried, tested and protected than the latest electrickery product from Boeing.

That's what's wrong with aviation nowadays - not enough of the Right Stuff!;)

FullWings

27th Feb 2013, 20:51

I think that's the main issue, from a pilot perspective.

Engines: Outside the pressure hull, multiple fire (heat) detection systems, multiple extinguishing systems (that work on the materials present), fuel, electrical, air and hydraulic isolation with one switch plus hot bits contained within a tested and certified armoured cylinder.

787 batteries: None of the above. :(

TURIN

27th Feb 2013, 21:40

Hi Tec
So they have these two large electrically driven compressors that require 270V DC power.

Make that four. Two per air con system.

After an aircraft lands from a flight, as engine bleed is still available, it is used to start APU as in B777.

B777 is the only type I can think of with a pneumatic starter (in addition to electric).
Are there others? A380 perhaps?

Let me give an emergency situations where there is a total power failure on B777 and B787 at cruise altitude of 40,000 ft.
On a Boeing 777 the bleed air from the engines is still available, (Bleed valves stay open when power is removed), and this is used to automatically start the APU through a pneumatic starter. This source is unlimited unlike a battery with a fixed charge. Bleed air is also available for pressurization of aircraft, so the crew, if they are 40,000 ft, need not worry about pressurization, and when APU starts, power is also restored. Crew have to deal with only the electrical failure during this critical period.

Have there been many (any?) total electrical power failures that haven't been caused by loss of the engines too? I can't think of any.

Point being, the 787 has the same redundancy in regard to engine failure but increased redundancy with regard to electrical power-by a long way.
Four main generators instead of two.
Two auxiliary generators instead of one.

These power conversions generate heat and these panels that are located in the middle of the aircraft (Approximately below the first row of economy seats on ANA), are cooled using 2 large refrigeration units.

Not quite. There are two independent liquid cooling systems. Not refridgeration units. The power conversion units, ATRUs and CSMUs use this cooling fluid in a closed circuit.

Otherwise you're spot on. :}

saptzae

27th Feb 2013, 22:11

Main bat is needed for brakes after touchdown.

@Golf-Sierra
4 actuators x 8 wheels = 32 actuators. 150A /32 = that's just 4.68A per actuator.Sounds reasonable.

For inflight needs, the RAT will suffice.
http://farm8.staticflickr.com/7024/6790408327_e78df195c1_b.jpg
B787 with RAT deployed - Canon Digital Photography Forums (http://photography-on-the.net/forum/showthread.php?t=1143180)

FlightPathOBN

27th Feb 2013, 23:01

OT...wait until the wake vortex that this bird creates gets out....

(upswept bottom wing and outboard flaps) :eek:

virtually ALL of the images of the 787 show the RAT deployed on ARR...WTF?!?!

I would really like to see the fuel econ numbers with the 2 gen/engine....

edit:

So if you go EO on the 787...where does the power to op everything come from?

inetdog

27th Feb 2013, 23:22

So if you go EO on the 787...where does the power to op everything come from?
By design, from the APU and the RAT, with the batteries as a backup for essential systems if it comes to that.
The batteries should not be switched onto the main DC bus until after non-essential loads have been switched off. This is an active (solid state) relay and not just a diode isolator.

Kiskaloo

28th Feb 2013, 00:05

poorjohn
The table would have you believe that LiCobalt is a very poor performer compared to later Li technology. It would be interesting to know Boeing's supplier's reason for that choice.

Back in 2004/2005, it was the mainstream cathode chemistry. Many of these newer cathode chemistries either were developed or matured after the 787 program was in full development.

Momoe
Boeing are taking a beating partly because the planes aren't flying for a damn good reason, the other issue is Boeing's perceived lack of clear oversight across the design/implementation.

Designing aircraft batteries of any kind is not a core competency of Boeing Commercial Aviation. Yes, they are ultimately responsible for the decision to go Li-Ion instead of NiCad, but they chose Yuasa because of their expertise in aviation batteries and Li-Ion batteries for industrial uses.

ATC Watcher

28th Feb 2013, 06:42

TURIN : Have there been many (any?) total electrical power failures that haven't been caused by loss of the engines too? I can't think of any.

Total , can't recall either, but partial ones with severe consequences, yes.
This one for instance :

Martinair -- Further Information from AWST and FI (http://www.rvs.uni-bielefeld.de/publications/Incidents/DOCS/ComAndRep/MartinAir/martinair-summary.html)
The last lines of the text are interesting as to the consequences of even partilal E failures.
And this was on a good old cables /hudraulics airplane.

llagonne66

28th Feb 2013, 06:45

787 faces extensive tests to return to air, FAA chief says | Business & Technology | The Seattle Times (http://seattletimes.com/html/businesstechnology/2020443971_787huertaxml.html)

For the time being they seem to stay on the safe side ...
let's see how it flies under the Boeing's lobbying barrage ...

Spooky 2

28th Feb 2013, 07:33

Geeze do you think some of guys could let up....just a little? The deployment of the RAT is a function of the flight test program on every airplane prior to delivery. They deploy it to see if it works. What a novel idea.:ok:

JohnMcGhie

28th Feb 2013, 07:42

Two posters have suggested that the solution would be to remove the battery chargers and fly the batteries as "primary" cells that would be recharged only on the ground. That won't solve the problem.

The problem is "thermal runaway". As the battery gets hot, the internals expand, getting closer to each other, and thus increasing the likelihood of a short-circuit. The more often they are cycled, the greater the likelihood of a short-circuit.

The batteries get hot because of the current passing through them. While this happens to a certain extent during charge (at 2C which is about 130 amps for these cells) it is much worse during discharge (when the APU battery flows more than 1,000 amps for up to 30 seconds while winding up the APU). If it's going to catch fire, the problem is most likely to begin just after you "use" it. Removing the charger doesn't solve that.

The onset of thermal runaway happens at about twice the boiling point of water: this research shows these batteries are well into "coffin corner" by 200 degrees Celcius: Modeling Thermal Runaway for Safer Lithium Ion Batteries (http://www.comsol.com/stories/kobelco_lithium_ion_batteries/full/)

As Lomapaseo points out, hot fires are successfully contained by metal cans every day: in things called "engines". I suggest that Lithium Ion batteries, with a known propensity to spontaneously combust, should be contained in a fire-proof box whenever they fly, whether they are "in use" or not. We know these things are going to burn occasionally: we should ensure the tail (or the cockpit!) doesn't fall off the aircraft when they do. Either would cause the flight crew to think unkindly of the designer/manufacturer.

My greater concern is not that these batteries catch fire, but that they fail! On a fly-by-wire aircraft, that gives a whole new meaning to the term "dead stick". Yes, I know almost everything else has to fail before this matters. But consider Sully's celebrated ditching:

He lost both engines. His APU was not running. If his batteries had failed, and his aircraft had been a 787, he would have had no flight controls. At all.

I think the pilots on this forum would be more than anxious to have this possibility designed out. Before they have to fly a 787 again...

It is easy to see why Boeing chose the Lithium Ion battery. Consider the following article (especially the table it contains):
Rechargeable battery - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Rechargeable_battery)

Here, I have sorted the data by "Watt/Hours per Kilo":

Type Energy density
(Wh/kg)
Lithium-air (organic)[7] 2000
Lithium sulfur[10] 400
Lithium-ion 200
Molten salt 180
Lithium-ion polymer 165
Sodium-sulfur 150
Silver-oxide 130
Lithium iron phosphate 100
Lithium–titanate 90
Alkaline 85
Zinc bromide 80
Nickel–hydrogen 75
Nickel–zinc 60
Nickel–metal hydride 55
Nickel–iron 50
Nickel–cadmium 50
Lead–acid 35
Vanadium redox 30
Sodium-ion[13] 0
Thin film lithium 0

Sorry, the PPRuNe website doesn't like tables, but you can get the idea. Leaving aside the two outliers at the top that are not on-sale yet, Lithium Ion comes in third. Molten salt is a little aviation-unfriendly.

But Lithium iron phosphate would be my pick. Twice the energy density of NiCad, and already approved for aviation service in an application I know about. OK, they are electrically "fragile", which means you have to pay very close attention to the design of the charger: one spike and they are trash. But that's probably what happened to the 787 batteries.

The benefit of the LiFePo battery is that it does not catch fire when it fails. Another benefit is that it has a very low internal resistance, which enables it to withstand truly prodigious discharge rates (APU starting...) without suffering. And they have around 5 times the in-service life.

Just my thoughts

Walnut

28th Feb 2013, 07:46

Hi Tech, I agree with your analysis. but as a commercial pilot of 36yrs & 20K hrs I thought I would look more deeply at what is still a fine a/c.
Multiple failures of systems are a pilots worst nightmare & the Hudson river incident would not have been successful if the Capt had not pre-empted the cck list & started the Apu.
I see the flying controls have 3 hydraulic systems, with the centre electrically powered, so with a double engine failure it is essential to start the APU, (from the battery)? I appreciate the windmilling engines should provide some output of both electrical & hydraulics but again the pilot is faced with pressurisation problems (High Techs) and how to restart engines at 40000ft without electrical power.
I note that the a/c needs 2 GPUs to provide engine starting, I have been to numerous outstations where you are lucky to get even one doubtful unit.
Boeing have said this a/c is a game changer, I agree, but it is very complex, and as such I can see lots of down line problems.

Pub User

28th Feb 2013, 07:54

poorjohn

even after two fires and an OAG (sic) fleet the best way forward is still to leave everything as unchanged as possible, and put a steel box around it.

I think there's a lot more involved in the proposed modification than just putting a box around it. There is talk of cell re-design and battery modification to isolate cells thermally.

Walnut

so with a double engine failure it is essential to start the APU, (from the battery)? I appreciate the windmilling engines should provide some output of both electrical & hydraulics but again the pilot is faced with pressurisation problems

The 787 starts the APU automatically in the case of a double engine failure, yes from the battery, but it would be assisted by windmilling engines and the RAT.

The pressurisation problems are no worse than any other twin when faced with a double engine failure. You're going down anyway, so the most important action for loss of pressurisation is already initiated!

inetdog

28th Feb 2013, 08:13

You can do some WYSIWIG formatting of tables by wrapping the table text inside CODE tags (The # format button in the toolbar).

Type Energy density
(Wh/kg)

Lithium-air (organic)[7] 2000

Lithium sulfur[10] 400

Lithium-ion 200

Molten salt 180

Lithium-ion polymer 165

Sodium-sulfur 150

Silver-oxide 130

Lithium iron phosphate 100

Lithium–titanate 90

Alkaline 85

Zinc bromide 80

Nickel–hydrogen 75

Nickel–zinc 60

Nickel–metal hydride 55

Nickel–iron 50

Nickel–cadmium 50

Lead–acid 35

Vanadium redox 30

Sodium-ion[13] 0

Thin film lithium 0

This will work best if you have formatted the table in a straight text editor and not a word processor and have used a monospace font such as Courier. Try to avoid using TABs if possible.

inetdog

28th Feb 2013, 08:48

Walnut
I note that the a/c needs 2 GPUs to provide engine starting, I have been to numerous outstations where you are lucky to get even one doubtful unit.
I believe this is one reason that the APU can be started by either battery or ground power. The APU can then start the engines, one at a time.
If there is no fuel on board for the APU, the main battery will power the fuel transfer system to allow fuel to be added and made available to the APU.
... but again the pilot is faced with pressurisation problems...
I also believe that since pressurization is provided by electrically powered compressors rather than air bleed, minimal cabin pressurization can be powered from the APU or even just the RAT.

Spooky 2

28th Feb 2013, 09:00

The RAT has absoulutely nothing to do with pressurizing the aircraft. It simply does not have the capability to power the CACs and thus is limited to only the most essential items needed such as hydraulics and flight instruments.

TURIN

28th Feb 2013, 09:03

My greater concern is not that these batteries catch fire, but that they fail! On a fly-by-wire aircraft, that gives a whole new meaning to the term "dead stick". Yes, I know almost everything else has to fail before this matters. But consider Sully's celebrated ditching:

He lost both engines. His APU was not running. If his batteries had failed, and his aircraft had been a 787, he would have had no flight controls. At all.

The 787 also has individual back up batteries for the three ACEs (Actuator Control Electronics-part of the fly by wire system) they are also Li-Ion. The 777 is similar.

I note that the a/c needs 2 GPUs to provide engine starting, I have been to numerous outstations where you are lucky to get even one doubtful unit.
Boeing have said this a/c is a game changer, I agree, but it is very complex, and as such I can see lots of down line problems.

It's worse than that. Two GPUs is the absolute minimum-engine start cycle can be up to 3 mins due to the lack of power.
For optimum engine starting a third GPU is required-plugged in at the aft EE bay area.

As has been said, getting two 90Kva GPU supplies is hard enough, but three? FORGET IT!

Golf-Sierra

28th Feb 2013, 09:39

Have there been many (any?) total electrical power failures that haven't been caused by loss of the engines too? I can't think of any.

Qantas 747's galley leak caused system failure: ATSB report (http://www.smh.com.au/travel/travel-news/qantas-jumbos-water-leak-knocked-out-systems-report-20101213-18v2a.html)

TURIN

28th Feb 2013, 11:17

Not a total electric failure though. Three of four.

Close but no cigar. :ok:

Hi_Tech

28th Feb 2013, 11:24

B777 is the only type I can think of with a pneumatic starter (in addition to electric).
Are there others? A380 perhaps?

A380 has no pneumatic starter. No other aircraft I know of has one.

Have there been many (any?) total electrical power failures that haven't been caused by loss of the engines too? I can't think of any.

Only major failure when all power was lost on B787 was in the Loerdo incident, when there was a total loss of power and the RAT deployed. As they were on approach at that time they continued in that condition. Details of that incident are sketchy. There was a major fire in the central Electronics bay, where all power panels are located. I don't think NTSB got involved as the aircraft was still in the test phase. The reason for the power loss and fire according to Boeing was FOD !!!
Then there was the United incident and diversion to New Orleans, where power loss from one Gen was not properly restored from the other good generators. When you have 6 Gens loss of one Gen should be a piece of cake. Again the details are sketchy.
The same problem occurred again on a new Qatar B787 after delivery flight. The details are once again limited. the out burst of it's Chairman against Boeing is well documented.
Boeing has mentioned that these problems are now sorted out.

During my time in aviation there were some incidents of total power loss on different aircraft, but did not result in any accident. In one instance the aircraft was B777 that was dispatched with one gen inoperative, and other side engine failed for an unconnected reason. But as the APU was already running, power was automatically restored.
One remarkable incident was on a A300-600, belonging to a charter airline, that was positioning to an MRO. It was dispatched with one Gen inoperative from far east and when over India the other Gen also failed. The flight continued all the way to France with just APU. It was a ferry with just 2 crew. Still it was remarkable that the crew had faith on the APU for 6-7 hours. When I met the crew after landing, both Mexican, I had to tell them that they were bravest crew I have ever met to have faith in the APU for 7 hours.
On airbus there is detector called Avionic smoke Detector, which can trigger a warning (Most instance false), the crew have to kill most of the power and land ASAP. This has happened several times, a recent one is on Air Canada 320 at Edmonton.
Incident: Air Canada A320 near Edmonton on Aug 18th 2012, avionics smoke indication (http://avherald.com/h?article=454b051a&opt=0)

deptrai

28th Feb 2013, 11:49

Airbus knows when it potentially has a tool to beat its competitor over the head with. Not in an overt way mind you - there will be subtle reminders...

Leahy already jumped on it, in a not so subtle way (quoting from CONF iture's link):

When Airbus redesigned the A350 seven years ago to create the all-new XWB, Leahy admits that he pushed the engineers to follow Boeing's lead on all-electric architecture. But he is pleased he was overruled. Airbus engineers went "back and forth" three times about whether to equip the XWB with electric brakes before deciding to stick with conventional hydraulic architecture. "I'm guilty as the commercial guy for pounding the table saying 'look [the 787's] all-electric - it's game-changing'," Leahy admits. But trade-off studies by Airbus engineers could not justify adopting the technology. Leahy says: "They told me: 'You're not going to like the reliability - it's going to be complex, heavy, and hard to maintain'."

Hi_Tech

28th Feb 2013, 12:32

Quote:
I see the flying controls have 3 hydraulic systems, with the centre electrically powered, so with a double engine failure it is essential to start the APU, (from the battery)?

My original post was just to high light how Boeing are in a pickle by doing away with engine bleed. Though a bit old fashioned, engine bleed was reliable power source. Without bleed we need huge power source from generators and batteries etc, and has actually created a problem on basic electric systems which normally do not have any serious problem on most aircraft these days.

Volume

28th Feb 2013, 13:01

engine bleed was reliable power sourceEngine bleed is expensive to maintain, leaks are common and potentially dangerous. Interflug lost an Il-62 due to a bleed air leak causing a fire.

Kerosene Kraut

28th Feb 2013, 13:19

The Interflug Il-62 crashed back then because of a leaky bleed air pipe crossing the little known cargo compartment between the engines burned through insulation and some electrical wiring which ignited some barrel of deicing fluid that was carried there (not permitted per regs). And all that led to a fire, loss of control, inflight breakup and loss of all lives.
The type received modifications afterwards.

ASN Aircraft accident Ilyushin 62 DM-SEA Knigs Wusterhausen (http://aviation-safety.net/database/record.php?id=19720814-0)

Hi_Tech

28th Feb 2013, 13:28

The RAT has absoulutely nothing to do with pressurizing the aircraft. It simply does not have the capability to power the CACs

It is like attempting to start your car with two AA batteries.

Hi_Tech

28th Feb 2013, 13:34

Engine bleed is expensive to maintain,

Only time will tell how expensive these CACs and power conversion equipment are to maintain.

Momoe

28th Feb 2013, 15:23

Kiskaloo,

Agreed, in that Boeing don't design batteries. They would have looked at the energy density values and at the design stage, Lithium-Ion would have been a no-brainer.

Yuasa's expertise in battery design is beyond reproach, however at this moment it's uncertain what caused the battery pack to ignite. While it may have been a faulty battery, we don't know if the cell spacing exacerbated the problem or if the charge/discharge algorithms were faulty or if it was an as yet unknown factor.

What is clear is that Boeing pretty much went all in on 'Electric plane' concept and this made the Lithium battery a commitment rather than a contribution.

I'm still slightly surprised that there were no indications of potential battery problems during the testing/flight testing regime, these normally take each system to the edge of the envelope, yet no issues reported?

Ex Cargo Clown

28th Feb 2013, 16:08

Ex Cargo Clown

28th Feb 2013, 16:14

I'm still slightly surprised that there were no indications of potential battery problems during the testing/flight testing regime, these normally take each system to the edge of the envelope, yet no issues reported? Business & Technology | Electrical fire forces emergency landing of 787 test plane | Seattle Times Newspaper (http://seattletimes.com/html/businesstechnology/2013387936_787emergency10.html) You been asleep for a few months? How on Earth did it get certified when a test A/C burst into flames?

Right Way Up

28th Feb 2013, 16:29

Have there been many (any?) total electrical power failures that haven't been caused by loss of the engines too? I can't think of any.

Qantas B744 Total electrical failure? [Archive] - PPRuNe Forums (http://www.pprune.org/archive/index.php/t-307604.html)

The 747-400s APU cannot be started inflight, apparently as failure of all 4 gens was thought impossible.

inetdog

28th Feb 2013, 18:40

Business & Technology | Electrical fire forces emergency landing of 787 test plane | Seattle Times Newspaper You been asleep for a few months? How on Earth did it get certified when a test A/C burst into flames?

Was the actual cause of that fire during test ever released? Was it perhaps a battery incident???

llagonne66

28th Feb 2013, 19:32

As it was a test flight, the incident has not been logged by the NTSB : List by Month (http://www.ntsb.gov/aviationquery/AccList.aspx?month=11&year=2010)
Therefore, no "official" report has been established by an independent body.
"Common" knowledge is that some FOD made its way in the aft electric panel and the whole thing burned down !
Flightblogger published a quite comprehensive summary of that incident No split over similar-looking wingtips - FlightBlogger - Aviation News, Commentary and Analysis (http://www.flightglobal.com/blogs/flightblogger/2010/11/boeing-near-end-to-787-fire-in.html)

glad rag

28th Feb 2013, 20:24

Do you have any references for that, toffeez.

llagonne66

28th Feb 2013, 20:37

Just type "like Radio Shack" in the Seattle Times search engine and you'll get the source :)

glad rag

28th Feb 2013, 20:45

Thank you.

saptzae

28th Feb 2013, 21:27

@llagonne66
Thank you, the Flight blogger link you provided, links to an interesting article The Seattle Times: Making It Fly (http://seattletimes.com/news/business/757/) on the 757 cert effort, dated 20 days before I flew out to HK.

It seems one had more time then to write up things like that, as well as to check things out thoroughly, in proportion to the complexity, that is.

ozaub

28th Feb 2013, 23:11

Mention of the 757 makes it opportune to note Boeing's difficulties with the introduction of aramid (KEVLAR) reinforced plastics on the 757/767. Aramid composites were chosen (in preference to carbon) on lightly loaded structure like trailing edge panels. Worked fine during certification but in real life temperature cycles caused aramid components to crack and absorb moisture within 4000 flight hours. All had to be sealed then replaced. A hugely expensive mistake. Service Bulletin 767-51-0008, April 1985 refers.

EEngr

28th Feb 2013, 23:54

Momoe (http://www.pprune.org/members/231371-momoe);

I'm still slightly surprised that there were no indications of potential battery problems during the testing/flight testing regime, these normally take each system to the edge of the envelope, yet no issues reported?Not so close to the edge during flight tests. Subsystems are usually pushed much harder during bench (lab) testing. And therein lies a possible problem. With much of the testing being done by the subsystem vendors, the interactions between different subsystems may not have been tested adequately.

Its more likely* that Thales loaded the battery system down with a resistive load bank to simulate an APU start rather than actually obtaining production DC-AC converters and an APU starter/generator.

*Disclaimer: I wasn't there. But this has been my experience with past subsystem tests.

Brian Abraham

28th Feb 2013, 23:56

An email doing the rounds at the momentFor one thing the problem may not be with the batteries themselves, but with the control system that keeps the charge on them at a given level. And the 'battery problem" is just one problem in many. Last week I had my regular monthly lunch with 5 fellow Boeing engineers (all but one retired) and we talked at length about what we call the "nightmare liner". We all agreed we will not book a flight on one. The one engineer still working (at age 74!!) says the news from inside is not good, and that there are no quick fixes for the multitude of problems that the 787 has.

The disaster began with the merger with McDonnell-Douglas in the mid-90s. The McD people completely took over the Board and installed their own people. They had no experience with commercial airplanes, having done only "cost-plus" military contracting, and there are worlds of difference between military and commercial airplane design. Alan Mulally, a life-long Boeing guy, was against outsourcing as President of Boeing Commercial Division, but instead of making him CEO after he almost single-handedly saved the company in the early 90s, the Board brought in Harry Stonecipher from McDonnell-Douglas, who was big on outsourcing. Stonecipher was later fired for ethics violations, and then the Board brought in Jim McNerney, a glorified scotch tape salesman from 3M and big proponent of outsourcing, to develop the 787. (Alan Mulally left to become CEO of Ford and completely rejuvenated that company.) A McNerney and his bean-counting MBAs thought that instead of developing the 787* in-house* for about $11 billion, they could outsource the design and building of the airplane for about $6 billion. Right now they are at $23 billion and counting, three years behind in deliveries, with a grounded fleet. That's typical for military contracting, so McNerney and the Board probably think they are doing just fine. But it will destroy Boeing's commercial business in the same way McDonnell wrecked Douglas when they took over that company decades ago. Boeing had a wonderfully experienced team of designers and builders who had successfully created the 707, 727, 737, 747, 757, 767, and 777 in-house, always on-time, and mostly within budget, and with few problems at introduction. That team is gone, either retired or employed elsewhere. (I took early retirement after the McD takeover of Boeing because I knew the new upper management team was clueless.) The 787 was designed in Russia, India, Japan, and Italy. The majority of the airplane is built outside the US in parts and shipped to Seattle and Charleston for assembly. *Gee, what could possibly go wrong? * Answer: just about everything. Because the McD people that now run Boeing don't believe in R&D, the structure of the airplane will be tested *inservice*.

Commercial airplanes in their lifetime typically make ten times as many flights and fly ten times as many flight hours as military airplanes, so the argument that composite structure has been "tested" because of the experience of composite military airplanes is just so much BS. So structure is a big issue. The airplane is very overweight. The all-electric controls have the same lack-of-experience issue that the structure has. The only good news for me is that the Boeing pension plan is currently fully funded, although it may not stay that way as the 787 catastrophe develops.

80-87

1st Mar 2013, 04:13

From the newswires....

Japan Airlines has further extended the suspension of its Boeing 787 operations to 31 May, three days after a similar announcement from its peer All Nippon Airways.

Momoe

1st Mar 2013, 05:54

Ex Cargo Clown

You been asleep for a few months?

Sharpen up mate! I was specifically referring to battery issues, the Laredo incident wasn't battery related or only indirectly in that if you short out the electrics by leaving an unsecured tool in the electrical bay you're asking for trouble.
Embarassing, yes. But it's nowt to do with the Lithium-Ion design issues.
Certification process is under scrutiny, but you can't expect any certifying agency to look at this incident and somehow extrapolate that the battery design is suspect.

Boeing accept that the current battery design isn't fail-safe, which is why they're proposing a fix. What most of the community on here are concerned about is the perceived nature of that fix, in that it's not appropriate for the job.

toffeez

2nd Mar 2013, 06:52

"you can't expect any certifying agency to look at this incident and somehow extrapolate that the battery design is suspect."

No, but there is a link which the FAA is aware of: the behaviour of the composite fuselage structure when exposed to extreme heat.

In the Laredo incident the fuselage insulating blankets caught fire, but the plane diverted quickly.

Boeing's battery "fix" allows the possibility of flying up to 3 hours with a very hot steel box under the floor. 1500 miles to the nearest firefighter.

Sure, the composite's fire resistance has been tested, but so were the batteries.

AmericanFlyer

2nd Mar 2013, 11:51

I've seen several comments on not knowing the root cause of the battery failure, yet about ten days ago All Nippon Airways made this statement: Japan probe finds miswiring of Boeing 787 battery on ANA flight that made emergency landing | StarTribune.com (http://www.startribune.com/business/191989441.html?refer=y)

"TOKYO - A probe into the overheating of a lithium ion battery in an All Nippon Airways Boeing 787 found it was improperly wired, Japan's Transport Ministry said Wednesday.
The Transport Safety Board said in a report that the battery of 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 APU from doing damage."

Joetom

2nd Mar 2013, 14:56

Root cause of battery failure
I've seen several comments on not knowing the root cause of the battery failure, yet about ten days ago All Nippon Airways made this statement: Japan probe finds miswiring of Boeing 787 battery on ANA flight that made emergency landing | StarTribune.com

Americanflyer.

Root cause and they found miswiring may not be linked to these events.

Miswiring is often found, not perfect, but will not always cause problems.

These events are not looking like a single problem and also not looking like a quick fix.

Both Boeing and the FAA with have to fully understand how this system was certified and allowed such shortfalls getting through the system.

Then understand how 100/150 batts could be replaced in service life and just waiting around to see what happens next, keep changing batts at that rate or hoping newer batts will fix the problem.

I'm guessing Boeing were working hard on these batt issues before the two events than got the aircraft grounded, maybe they should of been working harder.

The A350 team have been handed a golden egg with the 787 problems, am sure they will make the most of it, maybe they they will see it as pay back for the A380 spoiler/748i saga.

I hope the 787 gets fixed sooner than I think it will, what an aircraft after MSN 90 and they get the weight down.

EEngr

2nd Mar 2013, 16:08

Joetom (http://www.pprune.org/members/109951-joetom):

Then understand how 100/150 batts could be replaced in service life and just waiting around to see what happens next, keep changing batts at that rate or hoping newer batts will fix the problem.There are several entities involved in this chain of responsibility: Boeing, Thales, GSYuasa, Securaplane. Remind me if I've left anyone out. Before the fires, this was already a touchy issue. Who is responsible for and gets to pay for the maintenance? After the fires, I'm guessing that not one memo moves within or between any of these companies without corporate legal going over it with a fine-toothed comb.

I'm guessing Boeing were working hard on these batt issues before the two events than got the aircraft grounded, maybe they should of been working harder.Both Boeing and the FAA with have to fully understand how this system was certified and allowed such shortfalls getting through the system.Bothof these address process issues. and that is something which Boeing (and others?) regard as sacrosanct. Engineering and/or manufacturing errors? No problem. We'll fix them. But tell us how to manage the processes? That is going to result in some Boeing stonewalling.

When I was at Boeing, the very idea that some regulator could come in and tell us how to do business caused many managers to see red. Even when FAA mandated process changes saved us money, there was still a feeling that they should buzz of and leave us alone. I'm guessing that, what with outsourcing issues, Boeing is even more sensitive about this now.

Joetom

2nd Mar 2013, 16:31

EEng

Quote.

There are several entities involved in this chain of responsibility: Boeing, Thales, GSYuasa, Securaplane. Remind me if I've left anyone out. Before the fires, this was already a touchy issue. Who is responsible for and gets to pay for the maintenance? After the fires, I'm guessing that not one memo moves within or between any of these companies without corporate legal going over it with a fine-toothed comb.

If parts are on spec and tested as reqd, Boeing will have to pick up the tab on this one, FAA will also pick up some.

History shows us, testing parts on rigs and the like is not the same as bolting them together on the aircraft and operating it as far as possible to service life needs, and even operating test aircraft for years during delayed introduction in to service life (like the A380) still takes years of service life to get them stable.

FlightPathOBN

2nd Mar 2013, 20:54

It should also be noted that the 787 battery/system was designed prior to the current RTCA testing rules. The battery/system was NOT tested according to the current standard.

DozyWannabe

3rd Mar 2013, 04:00

@Brian Abraham:

I'm sure there's a kernel of truth in that email, but one glaring omission is the fact that the B777 had significant Japanese design and supply input, with airframe elements being supplied from Italy, Brazil and Australia.

Turbine D

3rd Mar 2013, 15:28

Dozy,
but one glaring omission is the fact that the B777 had significant Japanese design and supply input
Actually so did the 767. There are some interesting charts in this paper:

http://dspace.cigilibrary.org/jspui/bitstream/123456789/786/1/Boeings%20Diffusion%20of%20Commercial%20Aircraft%20Design%20 and%20Manufacturing%20Technology%20to%20Japan.pdf?1

Stonecipher & McNerney both came out of GE Aircraft Engines. Both saw the benefits of outsourcing ("Share to Gain") demonstrated by CFMI and the CFM56 engine family and then the GE90. Perhaps though, they both missed the fine points of what it takes to manage and oversee a successful outsourced program.

ImageGear

3rd Mar 2013, 19:08

Don't know the guys but what odds that one was an Engineer and one was a beancounter ? :E

Turbine D

3rd Mar 2013, 20:50

ImageGear,
Don't know the guys but what odds that one was an Engineer and one was a beancounter ?
Pretty good odds:ok:

Mulally was an engineer, graduated from the University of Kansas with a Masters in Aeronautical & Astronautical Engineering and then was a Sloan Fellow at MIT. He went to work directly from there to Boeing. He lead the team at Boeing that designed the two-man common cockpit for the 757/767 aircraft and then moved on to the 777, first as Director of Engineering, then as VP and GM.

Stonecipher received a degree in physics from Tennessee Tech, went to work for Allison as a lab technician then went on to work at GE Aircraft Engines, working his way up to become VP of Commercial Engine Sales. He left GE and went to Sundstrand, then to McDonnell Douglas and then to Boeing. He was somewhat more of a bean-counter than an engineer.

ozaub

4th Mar 2013, 01:49

When I worked at Boeing on 747, one company slogan was "quality is king". To which we added "but the schedule is God". Another slogan was "pride in excellence". Sadly Boeing now seems to have neither excellence nor pride.

tango.golf.romeo

4th Mar 2013, 13:39

Just looked at the Boeing website into the section dedicated to the 787 story. The main page explains to public the change control process at Boing in popular terms. Which indicates, I think, that they are redesigning 787 electrics now.

barit1

4th Mar 2013, 14:14

Turbine D:Stonecipher ... VP of Commercial Engine Sales. He left GE and went to Sundstrand, then to McDonnell Douglas and then to Boeing. He was somewhat more of a bean-counter than an engineer.

I had some minor contact with Harry - enough to learn that he had little knowledge of aviation culture and slang/euphemisms. But despite this he was quite a salesman (and not just selling airplanes or engines :}).

WHBM

4th Mar 2013, 14:50

Stonecipher came with the McDonnell Douglas purchase, having presided over the sales of their commercial types having fallen off a cliff in their final years leading to the demise of the company, a fact which the appointing board of directors at Boeing somehow seem to have missed. Remember what the market has thought of those final McDD products, the MD-11 and the MD-90 ? He didn't last too long at Boeing's helm but certainly set the style for his successors that knowledgeable engineers are bad/expensive, competent aerospace professionals promoted to top management are worse, and marketing gloss is the way to go. Predecessor Phil Condit was seemingly derided for being a longstanding PPL and having his own light aircraft for weekends, let along for being a Boeing lifer. The fact that the 777 programme that he had been in in charge of smashed Stonecipher's MD-11 commercially in the final years of McDD didn't go un-noticed.

McNerney seems of the same mould. I can't imagine how he is still there after seven years in charge, totally responsible during the multiple 787 fiascos with billions of stockholders money down the drain. Again, what are the board of directors thinking of. I don't believe we would be where we are with the 787 mess today if Phil Condit or Alan Mulally, or those of comaprable ability and understanding, were in charge.

DozyWannabe

4th Mar 2013, 15:16

The fact that the 777 programme that he had been in in charge of smashed Stonecipher's MD-11 commercially in the final years of McDD didn't go un-noticed.

Well, there are a lot of factors to that. The DC-10 "Death Cruiser" debacle effectively shredded the reputation of the Douglas name, plus the MD-11 ("Digital Death Cruiser" or, as one wag had it, "More Death II") was an underwhelming product and went against Douglas's reputation as the most traditionalist of US airliner manufacturers.

I think the biggest factor was that they gave the MD-11 project the green light without performing due diligence on the effect ETOPS would have on the market that they were intending to sell the MD-11 into. Failing to notice that this would accelerate the dwindling numbers of tri-jets on long-haul routes was a massive error in business strategy.

FlightPathOBN

4th Mar 2013, 16:54

When I worked at Boeing on 747, one company slogan was "quality is king". To which we added "but the schedule is God". Another slogan was "pride in excellence".

Truth is what stands the test of experience...AE

Turbine D

4th Mar 2013, 21:10

barit1,
I had some minor contact with Harry - enough to learn that he had little knowledge of aviation culture and slang/euphemisms.
Good observation, I did as well, at GE, MD and Boeing. At MD, besides the commercial side of the business, the DOD folks were all over him for the way parts were being designed and manufactured that added cost into military aircraft rather than taking cost out and he asked for some help. At Boeing, he saw some things that could be changed along the same lines and asked for help again. IMO, his problem was the lack of tact in getting changes made in cultures that were unlike the culture he grew up in which wasn't Engineering.

WHBM,
McNerney seems of the same mould. I can't imagine how he is still there after seven years in charge, totally responsible during the multiple 787 fiascos with billions of stockholders money down the drain. Again, what are the board of directors thinking of.
Exactly. He was not at GE Aviation as President very long. IMO, he was put into that position, running a business he didn't know much about (one of the three candidates to succeed Jack Welch as GE's CEO) to see how he would perform. When he wasn't selected, he left and became CEO of 3M Corp. There, he just about dismantled the Innovation and R&D areas which were key in their thousands of unique products developed over the years and business growth diminished significantly. He is not an engineer, a Harvard MBA type. Why Boeing, an aeronautical and technical engineering design and build company selected him is not clear to me at all.

Dozy,
I think the biggest factor was that they gave the MD-11 project the green light without performing due diligence on the effect ETOPS would have on the market that they were intending to sell the MD-11 into.
Correct. Not only did the 777s do in the MD-11s, eventually they did in the A-340s as well for more or less the same reason.

WHBM

4th Mar 2013, 22:15

He is not an engineer, a Harvard MBA type
We have to remember, what do airlines actually buy from airframe manufacturers. They do not buy MBA knowledge, they buy very sophisticated, well designed and built, clever, Engineering Products. That's what they are in business to sell. What a shame when those at the top don't understand this.

Which is why the 777 succeeded. The engineering design and implementation was spot on (well, apart from the noise back in the cabin).

FlightPathOBN

4th Mar 2013, 22:51

Boeing shifted from Engineering to sales.

With an engineered product, one barely needs a sales department, as the product sells itself on the engineering.

All one hears about is sales, discounts, and especially numbers...
Does anyone in the flow diagram care about sales numbers (other than the accountants) (ie, the aircraft is better because more have been sold?)

The segway into Ford Motor is telling, moving from hocking aircraft to hocking cars...

THAT is the major problem.

(ps..its not working...great engineering WORKS!)

galaxy flyer

5th Mar 2013, 01:48

I have to wonder if the stupid move to Chicago hasn't had its effects. Senior management, however unoriented to engineering realities they are, being 2,000 miles away cannot have helped.

For a successful technology, reality must take precedence over public relations, for Nature will not be fooled

Richard Feynmann

airsound

5th Mar 2013, 07:41

According to the London Financial Times, Ray Connor, the head of Boeing's commercial aircraft division, has been defending Boeing's refusal to ditch Li-ion, even though to do so might might have returned the aircraft more quickly to flight.

He also confirms more details about what they are actually going to do.

Boeing defends refusal to abandon 787 battery - FT.com (http://www.ft.com/cms/s/0/9fdb29d8-8500-11e2-88bb-00144feabdc0.html#axzz2Me3cH7bD)

toffeez

5th Mar 2013, 08:24

"With an engineered product, one barely needs a sales department, as the product sells itself on the engineering."

How I wish that were true. In reality the airlines set up a competition between Fleet A and Fleet B both of which can do the job, of course.

Engineers may advise the beancounters, but they're not at the table when the winning deal is thrashed out late at night.

Contract negotiators earn more than engineers because they can very visibly earn (or lose) their employer millions.

Falcon666

5th Mar 2013, 10:42

Thomson now reporting on the BBC that they are delaying the start of 787ops until beginning of July.
Think this may be optimistic as well!

TSR2

5th Mar 2013, 11:59

That BBC report also quotes

A further 473 Dreamliners have been ordered by at least 44 different airlines around the world.

I thought that Boeing had considerably more orders than that.

SMT Member

5th Mar 2013, 12:14

Total orders stand around 850, of which 50 have already been delivered.

green granite

5th Mar 2013, 13:12

Sorry fgrieu but it's still behind a pay wall.

toffeez

5th Mar 2013, 13:14

I get a box that invites me to "register for free".

Momoe

5th Mar 2013, 13:58

Read the article and it's not plausible, still got patch written all over it.

Article quotes Connor as saying the cells will have enhanced spacing, in a box which will vent to outside the aircraft. Fine so far but he then says that the batteries will be in an oxygen free environment to prevent fire.

Thermal runaway with Li-Ion generates it's own oxygen as part of the process or are they using 'special' batteries.

Article also quotes Connor as saying Airbus have made the right decision to revert to Ni-Cd at this stage, while defending Boeing's commitment to Li-Ion; Read as "We can't do that because it would take too long".

This re-affirms my belief that Boeing are out on a limb with the 'Electric plane' concept and are committed to the Li-Ion solution.

PEI_3721

5th Mar 2013, 14:12

With hindsight, these events suggest a failure of risk management.
Apparently Boeing did not have a preplanned strategy of what to do if the ‘risky’ choice of battery turned out to be an error – something which could have occurred up to the point of certification … and beyond. Perhaps they did not think ‘what if’, nor project sufficiently into the future – continued airworthiness.
There was no plan B, or alternatively that plan B was implemented as a solution for the flight test fire incident. This could suggest that the cause of the flight test incident was misidentified, or that the solution (plan B) was insufficient.

We have opportunity to learn from this.

“We take a risk. We can decide the return is worth it.
We run a risk. We can become victims if things go wrong.
When analysing risks you have to consider the whole range, from decisions to operate (behave) in certain ways, to decisions to act in certain ways.
When inspecting you have to examine the context, including yourself.
What happens to companies that run risks? The best make profits, the worst go bankrupt”. (P. Hudson)

tango.golf.romeo

5th Mar 2013, 14:16

Yes, it looks like they are redesigning the battery itelf. And it sounds to me that the redesign targets mostly the goal to prevent fire/smoke at all costs, rather than the goal to find out the cause for that extreme overheating. Which may mean, I think, that it is again a temporary solution to win some time to put the hardware back into the skies as quick as possible and then develop more effective and reliable solution when the pressure is over.

deptrai

5th Mar 2013, 14:49

from the FT article The company had also learnt the lessons of the severe delays and other problems with the 787, the first of which was delivered three years late. He held up the Boeing 737 Max – the latest version of the successful short-haul jet – as an example of how the company was no longer taking the same risks it took with the Dreamliner.
“We took on some of that risk knowingly and we’re not doing that again,” Mr Conner said of the Dreamliner.

honest statement :ok: and if they also can convincingly demonstrate that the 787 fix is safe, everything will be allright.

Turbine D

5th Mar 2013, 16:26

GF,
I have to wonder if the stupid move to Chicago hasn't had its effects. Senior management, however unoriented to engineering realities they are, being 2,000 miles away cannot have helped.
Funny you should bring this up. When he was at GE Aircraft Engines, he moved his office to the far end of the complex, as far away from the action as one could get,, but close to the sales marketing folks. I don't think many of the worker bees ever saw him walk the factory floor or visit the Engineering folks, reclusive is a good word description. At Boeing, video conferencing from Chicago doesn't hack it.

BTW I read this in a financial magazine (bolding is mine),
Boeing boosts 2011 pay 34 percent to $18.4 million for CEO Jim McNerney
Boeing CEO Jim McNerney’s compensation jumped 34 percent last year as the board of the big airplane maker rewarded him for delivering the new 787 and winning a huge Air Force order for refueling tankers.
Boeing revenue rose 6.9 percent last year, to $68.74 billion
Nothing like getting rewarded for delivering 787 aircraft 3 years late to your airline customers.:confused::ugh:

PEI_3721,
With hindsight, these events suggest a failure of risk management.
It isn't hindsight at all, it's like the risk management wasn't in the deck of cards, starting with the fuselage mating and fastener problems leading to the three year delay in delivery.

t.g.r.,
Yes, it looks like they are redesigning the battery itelf. And it sounds to me that the redesign targets mostly the goal to prevent fire/smoke at all costs
Probably is the only thing they can do in the short run if the FAA approves. I don't know why they don't stick the thing in a sturdy sealed, heat resistant box filled with argon or nitrogen, e.g., no fire and no smoke without oxygen.

fgrieu

5th Mar 2013, 16:36

I don't know why they don't stick the thing in a sturdy sealed, heat resistant box filled with argon or nitrogen, e.g., no fire and no smoke without oxygenLithium batteries (when charged) do not need extra oxygen/oxidizer to burn; they contain it, much like explosives do.

FlightPathOBN

5th Mar 2013, 16:43

fgr..concur...

they scrapped the Titanium enclosure when they figured out it is the only element that will burn using nitrogen...

Turbine D

5th Mar 2013, 16:43

fgrieu,

Thanks, I was wondering why and you answered it.:ok:

Joetom

5th Mar 2013, 17:50

Quote.

He began by reminding the audience that the problematic batteries are not used in flight !!!

That's ok then.

Quote.

will move really fast” once the Federal Aviation Administration approves the company’s certification plans to modify the Dreamliner’s lithium-ion batteries and systems relating thereto.

Once/if/maybe/maybe-not. Maybe-not is my guess

Why bother, just remove them and save more weight.

Reading between the lines, going A350 plan B batt option for the 787 is no simple option, guess it will require monster change and monster time to do.

Guess it's possible the A350 will be flying with the airlines before the 787 gets sorted out.

EEngr

5th Mar 2013, 19:38

galaxy flyer (http://www.pprune.org/members/62324-galaxy-flyer):

I have to wonder if the stupid move to Chicago hasn't had its effects. The mountains are high and the emperor is far away.

FlightPathOBN

5th Mar 2013, 22:36

PAXboy

5th Mar 2013, 22:39

galaxy flyer
I have to wonder if the stupid move to Chicago hasn't had its effects. Senior management, however unoriented to engineering realities they are, being 2,000 miles away cannot have helped.
Indeed. When I heard the move did not include the whole production facility - it was clear that it was being done to save money and nothing else. It was also clear that the Board were already entranced by their new hire to agree to such a remarkable thing.

In my current line of work, I visit many different premises that carry out the same function (nothing to do with flying). I see a BIG difference in the way they work: Some of them have the office remote from the operations and some have it 'close coupled'.

In one type of design, the manager is 1,000 yards (or more) down the road in another building. In the other, the manager is so close that, if there is a sudden change in the background noise - they will hear it in their office - and be outside in 15 seconds in among their customers.

In the first, if something goes wrong in the operations area they say, "You can ring the boss but he won't come and sort it" at the other they say, "I'll just pop in and tell the boss what's happened." You don't have to take long to work out which type of establishment works better and has happy customers ...

MWorth
Ray Conner spoke in New York yesterday, saying that the company would move "really fast" to get the Dreamliner back in the air following FAA certification plan approval.Ah yes, get a plan for approval and then work to the plan for approval. That's the way to engineer in the 21st century.

Turbine D
Funny you should bring this up. When he was at GE Aircraft Engines, he moved his office to the far end of the complex, as far away from the action as one could get, but close to the sales marketing folks. I don't think many of the worker bees ever saw him walk the factory floor or visit the Engineering folks, reclusive is a good word description. At Boeing, video conferencing from Chicago doesn't hack it. The ONLY thing to do is to walk around the 'shop' be it an office, a department store, or a factory. TALK to the people at the coal face and you will learn what you need to know.

But Boeing was due for a fall. They had become global top dog and yet they still wanted more profit. When that happens, if the shareholders and bonus catchers won't accept "Steady as we go, doing good work" then they start cutting chunks of the company out and retiring the long standing employees who know what to do in a crisis. Mainly because they were there in the LAST crisis!

Subsequently, Boeing found themselves in the same position as their legacy carrier clients! They were big and fat and, because they were top dog, thought that they knew how how to do it. They had become so brain damaged by success that they had no concept of failure. When the failure arrived - they were caught in the headlights and had no idea how to handle it.

Posters ask how the Board allows this to continue? Boards don't like admitting they have made a complete stuff up and are STILL running the company over the edge. So they have to pretend that they know what they are doing. From what has been written about this CEO, he is obviously a spectacular speaker and can convince people face to face of almost anything. Saying No to him will take a lot.

The only thing that will change that are deaths or large amounts of money. They have, thus far, avoided the deaths so when the large amounts of money start rushing out of the door - he will follow.

For the record, I have never worked in the airline industry but was in IT and telecoms for 27 years, working for a very wide range of companies (finance, shipping, cargo, retail, etc) in many different countries, including the USA. I specialised in big projects and I've made my fair number of mistakes.

lomapaseo

6th Mar 2013, 03:06

FAA faces obstacles in approving Boeing Dreamliner fix

"The NTSB has questioned the process Boeing and the FAA used to certify the plane."

"Weber speculated that the safety concerns may result in regulators restricting the 787's ability to make long flights over water, a standard known as ETOPS. Such a change would be a severe blow to Boeing and airlines that use the Dreamliner for long-haul direct flights with about 250 passengers, a highly lucrative market that the 787 can serve at 20 percent lower fuel cost than other planes."

A very confusing article. It seems to purposely plant this confusion by making competing claims of what level of safety is required.

Of course the FAA will be 1000 percent sure that it meets the regulated standards which are less than 100 % safe. All we should expect is the same level of safety that all new aircraft enter the fleet at.

That's why we code regulations so we have something to compare our sense of acceptable safety against, rather than a mix of weasel words by any person.

Momoe

6th Mar 2013, 14:28

EEngr

6th Mar 2013, 16:14

Weber speculated that the safety concerns may result in regulators restricting the 787's ability to make long flights over water, a standard known as ETOPS.Is ETOPS dependent on starting the APU? I don't think so, as dispatch with an inop APU is allowed (or so I've been told).

Battery capacity doesn't extend the range of the aircraft. That is done by the RAT (or APU, if it starts). The primary battery serves to provide short term power while the RAT deploys to keep critical instruments powered. And it provides emergency braking power, which is not an ETOPS range issue.

The battery function is binary. It either works or it doesn't. And the trouble it causes by not working is not range or capacity dependant. If the primary battery isn't there upon main power loss, the ensuing problems occur immediately. Not after 90 or 120 minutes. So a main battery failure will affect any length of flight or diversion capabilities.

HazelNuts39

6th Mar 2013, 16:34

I think Weber is correct in speculating that reduced battery reliability will affect ETOPS limits. After a first failure that results in a decision to divert to an alternate, the probability of a second failure that results in the need to use the battery, and the probability that the battery will then have failed, increases with the remaining flight time.

Walnut

6th Mar 2013, 17:39

Whilst an a/c can dispatch with an inop APU, its Etops will certainly be compromised.
Because with a 50% reduction of electrical power following an engine failure on an all electrical a/c then load shedding would have to take place without the APU.
Don't forget the back up electrical hydaulic electrical pumps will kick in to pwr the lost engine driven hydraulic system just to add to the load problems.
So at this point it would be imperitive to land at the nearest suitable a/p. Hence the reduction in Etops capability with a U/S Apu.
People have a mistaken belief in the RAT, it is an emergancy pwr source of very modest pwr output, it certain will not give any output on ldg where electrical pwr is needed to stop the a/c.
An a/c can not dispatch without a servicable main battery, there are lots of vital services eg discharge of fire bottles etc where battery pwr is needed.
I said in an earlier posting that the removal of circa 150 batteries to date is very very significant. Only 2 caught fire so the rest must have been to under performing (low charge)??

Annex14

6th Mar 2013, 18:17

Concur with what you posted!!
The about 150 changed batteries indicate something ? Probably a desighn flaw ?
Obviously about 150 batteries were changed because they became outperformed of described limits, most probably too much power taken off the devices. Looks like the batteries are used far beyond design expectations.
A LiIon battery discharged below design limits needs a special treatment to become reusable again, if at all.
Probably - speculation - the two reported fires and runaways were caused by trying to charge the emptied batteries with onboard equipment not designed and capable to perform that task correct.
If this may be proofed correct, than there is a a real non realistic approach discovered in the desighn of the battery control and managemnet environment.
The specialists may correct me.

FlightlessParrot

6th Mar 2013, 19:03

I think the discussion of whether battery failure affects ETOPS has got a bit over-technical. The problem is not that the battery fails, but that it fails in such a way that it might start a fire in a part of the aeroplane not normally containing fires. That, surely, has some influence on how far away you get from a diversion.

I have no technical knowledge, but I live in Auckland, so ETOPS is a matter of existential concern to me. I even had to reassure myself the first time I flew in a 777 from AKL to LAX. Paxen like me choose airlines, sometimes based on the equipment they use, and although I like Air NZ, I'd be reluctant to fly with them on a 787 unless I was sure this problem was really, thoroughly, fixed. As I say, I have no professional knowledge, but I'm reporting in from the commercial reality.

FlightPathOBN

6th Mar 2013, 19:26

I havent seen the data, but given this aircraft is virtually all electric...what happens if you were dispatched APU non-op, and went engine out?

I suppose this is a very real scenario for testing...but the concern from the way the batteries in the front and back are linked together, it just make one wonder.

PickyPerkins

6th Mar 2013, 19:26

I should confess that I have not read every post on this thread, nor am I sure that I can even remember every one that I have read, but I would like to ask a question.

Just what do we know about the servive history of the two burnt-out batteries?

With 150 batteries replaced, and something like 50 aircraft in service, were either one of these batteries previously taken out of service and then returned to service after "special treatment".

Just curious.

FlightPathOBN

6th Mar 2013, 19:40

then there is this...

ANA says it had Dreamliner power distribution panel trouble three times

ANA says it had Dreamliner power distribution panel trouble three times - Yahoo! News (http://news.yahoo.com/ana-says-had-dreamliner-power-190343000.html)

EEngr

6th Mar 2013, 19:40

HazelNuts39 (http://www.pprune.org/members/305001-hazelnuts39):

the probability of a second failure that results in the need to use the battery, and the probability that the battery will then have failed, increases with the remaining flight time.I don't think you want to cut probabilities that close when it comes to critical systems. The difference between ETOPS/non-ETOPS range or flight time is on the order of 3:1 or 4:1.

If a combination of events cannot be shown to be extremely improbable (< 10^-9 per flight hour), then some backup system needs to be provided. The current LiON batteries' service history is several orders of magnitude less than what Boeing predicted. Not just the probability of fire, but of the battery functioning. That is significantly worse than 4 times.

Walnut (http://www.pprune.org/members/130772-walnut):

An a/c can not dispatch without a servicable main battery, there are lots of vital services eg discharge of fire bottles etc where battery pwr is needed.
I said in an earlier posting that the removal of circa 150 batteries to date is very very significant. Only 2 caught fire so the rest must have been to under performing (low charge)??That's the key. Dispatch with a serviceable main battery. And then that battery has to remain serviceable for the duration of the flight. The two fires plus removals puts the battery at such a high probability of failure that the battery system appears to need its own backup.

Mk 1

6th Mar 2013, 20:06

EEngr: while the RAT deploys to keep critical instruments powered. And it provides emergency braking power,

Correct me if I'm wrong, but the RAT needs airspeed to provide the force to spin the blades to create the electrical energy. The job of the brakes is to slow the aircraft upon landing - if airspeed (groundspeed?) and power generation are being reduced once the aircraft is on the runway, where is the energy that keeps the brakes applied? As the aircraft slows the RAT rotation slows ergo the power output decreases. Or are the brakes of the type that when engaged will 'lock' onto that position?

TURIN

6th Mar 2013, 20:08

Connor's reassurance that the batteries aren't used in flight isn't right?

What starts the APU in the air?
Also, the 787 also has electric brakes, no power, no brakes, yeah I know that the brakes aren't used in flight but I'd consider them a vital part of aircraft equipment.

The APU will be started in flight if power is lost in one engine by the power available from the remaining engine.
Battery will only be used to start the APU in flight if ALL electrical power is lost. EG Double engine failure.

The brakes are only powered by the main battery IF all other normal power sources are lost. IE both engine generators fail AND APU generators fail.

Connor is correct. :ok:

With 150 batteries replaced, and something like 100 aircraft in service

Only 50 a/c in service.

I havent seen the data, but given this aircraft is virtually all electric...what happens if you were dispatched APU non-op, and went engine out?

I suppose this is a very real scenario for testing...but the concern from the way the batteries in the front and back are linked together, it just make one wonder.

The two batteries are not linked. (Or shouldn't be:})

If APU is inop and you lose one engine you still have two good generators producing 500KvA.
If you lose that you are down to the RAT and (Main) battery only. Good luck with that. :eek:

Correct me if I'm wrong, but the RAT needs airspeed to provide the force to spin the blades to create the electrical energy. The job of the brakes is to slow the aircraft upon landing - if airspeed (groundspeed?) and power generation are being reduced once the aircraft is on the runway, where is the energy that keeps the brakes applied? As the aircraft slows the RAT rotation slows ergo the power output decreases. Or are the brakes of the type that when engaged will 'lock' onto that position?

In that situation the main battery provides the power for emergency brakes.

In a traditional hydraulic system the emergency brakes are provided by a compressed gas accumulator. The main battery serves the same function on 787 electric brakes.

Momoe

6th Mar 2013, 20:34

Turin,
thanks for the succinct clarification.

Getting back to the Laredo incident, IIRC, this had major electrical issues on approach and deployed the RAT to power basic instrumentation.

Did this affect the brakes? Even if they weren't working I'm assuming that the reverse thrust system was available?

TURIN

6th Mar 2013, 20:39

As far as I know the battery powered emergency brakes worked as advertised.

T/reversers are hydraulic so unless there was a problem with the power to the control circuits (which are independent) they should have been fine.

lomapaseo

6th Mar 2013, 23:23

If a combination of events cannot be shown to be extremely improbable (< 10^-9 per flight hour), then some backup system needs to be provided

It's not helpful to suggest a meaningless target rate (< 10^-9 per flight hour), unless you define what classifies as an "event". Some level of protections are achieveable, others are not for any parts of an aircraft you care to define.

I simply look at what is currently demonstrated over the last 20 years and judge according to that scale..

gas path

7th Mar 2013, 00:05

Most of the batteries were removed for low charge state. ie the towing switch left on or extended tows using the lights and brakes.
A full charge of the batteries will give approx 1hr use of power to the ACP, exterior lights, flt deck dome light, and brakes. This drops significantly with a lower voltage state. (15mins at 29.7v)
IIRC One of the 'failed' batteries, the a/c had dispatched with a battery message (that was at the time a MEL item).

inetdog

7th Mar 2013, 01:06

Mk 1:
where is the energy that keeps the brakes applied? As the aircraft slows the RAT rotation slows ergo the power output decreases. Or are the brakes of the type that when engaged will 'lock' onto that position?

From the public graphics of the brake system, a set of motor driven actuators compress and release a group of carbon disks. The worm gear drive appears to prevent movement except under power.
So if the brakes are applied to a certain pressure and corresponding braking torque, they will maintain that braking until the actuators are driven in the opposite direction.

The accompanying text says that the system gives "proportional control" of braking force.

If you wanted to, you could probably set the brakes before landing. :rolleyes:

HazelNuts39

7th Mar 2013, 09:01

you could probably set the brakes before landingLand with locked wheels and no anti-skid?

wiggy

7th Mar 2013, 09:07

Land with locked wheels and no anti-skid?

I suspect that's why there was a :rolleyes:

EEngr

7th Mar 2013, 16:34

lomapaseo (http://www.pprune.org/members/48942-lomapaseo);

It's not helpful to suggest a meaningless target rate (< 10^-9 per flight hour), unless you define what classifies as an "event".A combination of failures that lead to the loss of the aircraft. But in general terms, it depends on what you are concerned with. The important thing is that the requirement is given in terms of events per flight hour. So the issue of ETOPS/non-ETOPS, flight duration or time to an alternate field doesn't enter into the calculation. If the system reliability doesn't meet requirements, no flights should be permitted.

Yes, I understand the problem people are having flying around with a battery on fire. Assuming that can be contained, and the aircraft can be flown safely, that still doesn't address the issue of the battery not providing its intended function. Fire or not.

I fear that Boeing is using some weasel words surrounding ETOPS just to get the airplanes back in the air for PR purposes.

Zeffy

7th Mar 2013, 16:43

NTSB Docket (http://dms.ntsb.gov/pubdms/search/hitlist.cfm?docketID=54251&CFID=2871&CFTOKEN=67900912)

mm43

7th Mar 2013, 18:04

NTSB - Boeing 787 Interim Report - March 7, 2013 (http://www.ntsb.gov/investigations/2013/boeing_787/interim_report_B787_3-7-13.pdf)

Detailed analysis.

SMT Member

7th Mar 2013, 19:00

But, crucially, "due to the ongoing investigation no conclusions or recommendations will be offered at this time" (or words to the same effect).

Which makes me wonder whether the FAA will be comfortable signing off on Boeing's proposed "fix".

FullWings

7th Mar 2013, 19:01

Not too many surprises in the interim document but reading through the firemens' reports, I do wonder if we'd be dredging the ocean for the remains of a 787, had this occurred mid-flight. Must have used several hundred pounds of extinguishant and eventually had to hack the battery out of the aeroplane. 1hr 40mins to get it under control... :eek:

WHBM

7th Mar 2013, 19:02

One thing that seems to be developing is a split between the FAA and the NTSB, the Feds siding with Boeing, and the NTSB seeming to be coming to much more cautious views. I somehow get the impression that this also represents a split between the manufacturer and the purchasers/operators, along similar lines.

It really is surprising that Boeing still doesn't know the root cause, like why the battery shorted in the first place, and why the multiple safety systems then didn't work, which is what the NTSB seem to be gunning for, not so much the FAA. Has McNerney really outsourced everyone who might be expert in this ? De Havilland got to the root cause of the initially inexplicable Comet metal fatigue accidents when all the evidence was laying at the bottom of the Mediterranean. Boeing are fortunate that is not at all the case here.

Ex Cargo Clown

7th Mar 2013, 19:35

the a/c had dispatched with a battery message (that was at the time a MEL item) Please tell me that's not true

poorjohn

7th Mar 2013, 19:48

Per the NTSB report, after the APU starts, the APU battery must continue to supply power to the APU control electronics. When the JAL battery failed, the APU shut down.

FlightPathOBN

7th Mar 2013, 20:02

I think that once the general public reads the fire fighters account...things will have a bit of a different flavor going forward..

Note that there are public hearings schedule for NEXT month...this appears far from over...

In reading the NTSB report, and the article below, this appears to paint a very different picture than we have heard before...

The fire fighters were not aware of Li nor were able to contain the fire...the peripheral damage is certainly cause for alarm, and as the battery for the avionics is a UPS, very much cause for alarm...

in flight..well damn..

From Seattle Times...

Boston airport firefighters encountered sizzling liquid and a hissing, “exploding” battery when they entered the 787 at the center of a two-month-long National Transportation Safety Board investigation, according to documents released Thursday.

The NTSB said Thursday it plans two public hearings next month, one to explore lithium-ion battery technology in general and another to discuss the design and certification of the Boeing 787 battery system.

The safety agency announced the hearings as it released an interim factual report and 499 pages of related documents on its investigation of the Japan Airlines 787 fire at the Boston airport on January 7.

Among the findings in the documents released Thursday:

• Boeing outsourced both the analysis and testing of the battery system’s safety, performed to get Federal Aviation Adminstration (FAA) certification, to its battery system subcontractor, Thales of France, and to the battery maker, GS Yuasa of Japan.

“Theses analyses and tests were performed by Thales/GS-Yuasa and reviewed by Boeing,” the NTSB states.

• The safety analysis by Thales and GS Yuasa determined that “overcharging was the only known failure mode” that could result in fire. Boeing therefore built safeguards into the system to “to ensure that the likelihood of occurrence of an overcharge event” was less than one in a billion — which is the usual FAA standard in providing for potentially catastrophic events.

However, there is no indication in the NTSB documents that the battery that caught fire was overcharged.

Investigators inspected a hefty electrical contactor — a relay switch — that is part of the battery management system and was designed to open the electrical points and disconnect the cells in the event of an overcharge.

The heavily blackened contactor was found to be “in the de-energized closed orientation,” meaning that no overcharge had registered with the system and the contactor had not disconnected the cells.

• The NTSB a month ago established that the fire instead started with an internal short circuit of a single cell in the eight-cell battery.

Boeing’s pre-certification testing did try to evaluate the effect of an internal short circuit. It chose to do so with a test that punctured a cell with a nail to induce a short circuit.

“This test resulted in venting with smoke but no fire,” the NTSB reported.

Boeing also consulted with other companies about their experience with the use of similar lithium battery cells and “based on this information, Boeing assessed that the likelihood of occurrence of cell venting would be about one in ten million flight hours.”

The 787 that caught fire in Boston had logged just 169 flight hours, the report states.

And the entire operational fleet of 787s had logged a total of 51,662 in-service hours, plus about 6,000 flight test hours.

• On the day of the Boston fire, the battery did not behave as Boeing or subcontractor Thales predicted.

The battery’s power discharge was “not at the constant rate described by the Boeing or Thales documents and included large changes and reversals of power within short periods of time,” according to the NTSB’s preliminary report.

• Sitting on a rack above the battery that burned was a smaller lithium ion battery, also supplied by Japanese manufacturer GS Yuasa, that is used to provide emergency power for the jet’s flight controls “for a minimum of 10 minutes when no other electrical power is available.”

Investigators found the exterior of this battery had been “lightly scorched” by the fire below and noted that its case had openings at the corners.

• No heat damage was found to any primary airplane structure.

However, the floor panel and carbon fiber floor support material, which are considered to be secondary structure, “were found to be heat damaged beneath where the APU battery had been installed.”

• The firefighters who were called to put out the fire did not know they were dealing with a lithium-ion battery, and had great difficulty putting out the intense fire.

When Capt. Mark Munroe of the airport’s aircraft rescue and firefighting (ARFF) unit entered the plane, he “saw heavy white smoke billowing through the floor” of the passenger cabin.

After locating the fire inside the electronics bay in the belly of the airplane, firefighters entered the compartment through dense smoke and applied shots of Halotron fire extinguisher to the battery.

Lt. David Hoadley of the ARFF unit reported that “It seemed like the fire did not want to go out, it kept rekindling.”

Then the battery “exploded,” according to Capt. Monroe.

“Capt. Munroe heard the battery hissing still and pushing white smoke or steam. There was liquid sizzling over the sides of the battery and still heavy smoke conditions. ... The battery continued to hiss before exploding.”

Monroe related that “he felt something hit him in the neck while he was in the airplane,” and he was sent out for medical treatment. “Something had burned his neck.”

Firefighters attempted to remove the battery from the jet, but found that the “quick disconnect” mechanism Boeing had included to allow mechanics to take out the battery for maintenance was “melted and un-recognizable” and a metal plate was preventing access.

The battery had to be cut out from the rack where it sat.

“With a hot battery and a gloved hand (Lt. Hoadley) could not access the bolts on the lower rails with tools. They attempted with pliers to remove the bolts for maybe 20 minutes. What looked like Teflon slides were burnt away and the battery would not move. There were 3 more screws that could not be removed.”

Firefighters cut away the metal plate, severed the battery wire, then “pried the battery loose with hydraulic spreaders and removed it.”

The battery was passed down to a firefighter and placed on the tarmac about 50 feet from the airplane.

The fire was declared under control an hour and forty minutes after the initial notification.

Boeing’s entire fleet of 787s has been grounded since a second battery incident during a flight in Japan, a week after the Boeing fire.

The company’s proposed fix for its battery system is currently under review by the FAA.

The agency expected to make an initial recommendation next week that will lay

NTSB: Boeing outsourced 787 battery safety analysis to subcontractors | Business & Technology | The Seattle Times (http://seattletimes.com/html/businesstechnology/2020505762_ntsb787reportxml.html)

toffeez

7th Mar 2013, 20:26

I respect your view but what does "GOING FORWARD" mean in your first line? To me it means nothing.
.

FlightPathOBN

7th Mar 2013, 21:24

toffeez,

I think that once the general public (ie Senators, Regulators, etc) reads the detailed account of the fire fighters, there will be a call for much higher scrutiny of the fix and certification moving forward. Technicalities aside, the first hand account was, to say the least, a bit alarming, and certainly something that no one wants to have happen (with themselves) on an aircraft.

There is also the issue of Boeing allowing other entities to perform the testing. This was specifically mentioned for a reason. While this may seem trivial, it is not trivial.

I also remember that early news releases stated that airport fire fighters were specifically trained with Li fires, but were unaware that the main batteries on the 787 were Li...this will add another level of equipage/training to the airport mix..

cockney steve

7th Mar 2013, 21:26

The fire was declared under control an hour and forty minutes after the initial notification.

Bit creative there, or what?...".burned itself out" is more like the truth.

Per the NTSB report, after the APU starts, the APU battery must continue to supply power to the APU control electronics. When the JAL battery failed, the APU shut down.
not had a chance to read the report, but surely, some of the APU's output is used to recharge it's own battery...surely that's the whole ethos of an emergency backup system...that it should be available and working in an emergency!

total "management" failure. imho.

FlightPathOBN

7th Mar 2013, 21:31

toffeez...

Note the latest 'news'

WASHINGTON (AP) — Firefighters and mechanics tried repeatedly to put out a battery fire aboard a Boeing 787 Dreamliner through smoke so thick they couldn't see the battery, according to documents released Thursday that portray the incident as more serious than previously described.

Boeing 787 battery fire was difficult to control - Yahoo! News (http://news.yahoo.com/boeing-787-battery-fire-difficult-control-185451469--finance.html)

Momoe

7th Mar 2013, 22:08

Having scanned the report, the reason for the differences of opinion between the NTSB and the FAA become apparent.

Boeing were keen to push the boundaries, hence the 'Electric plane concept' and it's dependence on Li-Ion.
However, this requires the FAA to re-evaluate it's stance on Li-Ion batteries and it consequently introduced new legislation which was designed to prevent the Boston event.

Subtle shift of emphasis away from Boeing and towards the FAA IMO, onus is now on FAA in two respects: firstly, to prove that their legislation was robust enough and secondly, their involvement and analysis on the test data.

On this side of the pond, we'd probably have an independent public inquiry where a senior civil servant chairs an independent team of experts who gather information, analyse said information and present their conclusions.

I assume that the Stateside equivalent would be a congressional inquiry?

sb_sfo

7th Mar 2013, 22:49

Stateside, this is about the best we're gonna get- NTSB is an independent body. Sadly, they can only make recommendations to FAA and Boeing. If this was the subject of a congressional inquiry, it would be a total partisan clusterfcuk.

However, if there were another incident, we could get a coroner's inquest if there were fatalities.

WHBM

7th Mar 2013, 22:53

Although many are looking at this NTSB report, published today, as new information, I bet there isn't a single item of fact about the event in there that was not known to the Boeing Board of Directors, and the FAA, within 24 hours of the happening. Which makes the Boeing response, of a stronger box being the answer, even more extraordinary. Just how much energy is inside waiting to be released when that, in turn, explodes ?

inetdog

7th Mar 2013, 23:45

poorjohn:
Per the NTSB report, after the APU starts, the APU battery must continue to supply power to the APU control electronics. When the JAL battery failed, the APU shut down.
And when the APU shut down, the ventilation to remove the smoke from the burning battery also shut down. In flight this might not have been as serious if the ventilation was also powered by the other generators and pressure difference to the outside. It does argue strongly that Boeing's proposed sealed case and pressure vent is a step in the right direction.

inetdog

7th Mar 2013, 23:52

FlightPathOBN:
The fire fighters were not aware of Li nor were able to contain the fire...
in flight..well damn..

I think that the firefighters may have been intellectually aware of how to contain the fire but gave too much weight to the directive to avoid damage to the equipment in the bay.
Water is the only thing readily available which will both cut off oxygen and cool the battery to prevent re-ignition. The training for flight crew on the other hand emphasizes the importance of water in fighting a Lithium battery fire very strongly. (Urinate on it if you have to... :) ) Do not try this in the middle of a compartment full of 400+ volt AC!
I would have hoped that the firefighters would have carefully resorted to water much earlier in the incident given that all power had been shut down.

In flight, on the other hand, extinguishing is just not an option:
Composite fire liners and a fire door separate the aft E/E from the aft cargo compartment. The aft E/E may be accessed through the aft cargo compartment if the compartment is empty. While the environmental conditions in the E/E are similar to the main passenger cabin above it, the compartment is not accessible from the main passenger deck.

vapilot2004

7th Mar 2013, 23:58

It is interesting to note the problems that occurred several decades ago when we made the switch from lead acid batteries, now ancient for commercial aerospace applications, to NiCads. The NTSB apparently recorded over a dozen incidents in one year back in the early 1970's. There were alarms sounded, and the same sort of doomsday talk and whinging that is heard today about the lithium-based types in the 787 filled the air back then.

After the teething issues were resolved, NiCads quickly became an industry standard for both private and commercial transport category aircraft. There were no crashes or fatal mishaps.

edmundronald

8th Mar 2013, 00:44

From page 34 of the NTSB report, this gem.

During this incident, the supply valves (which are electrically driven) lost electrical power after the APU shut down because the APU was the only source of electrical power being used at the time. As a result, smoke generated by the APU battery could not be effectively redirected outside the cabin and aft E/E bay.

I am sure lots of professionals on this forum will now step forward to explain that this is no problem.

I think before the 787 is let loose again, a test flight might be made with the families of some of the executives on board.

inetdog

8th Mar 2013, 00:48

Quote:
Land with locked wheels and no anti-skid?
I suspect that's why there was a :rolleyes:
I also did not specify how much brake pressure would be cranked in. It is a "proportional" system, but a little hard to guess without performance-based feedback.

inetdog

8th Mar 2013, 00:52

FlightPathOBN:
The NTSB a month ago established that the fire instead started with an internal short circuit of a single cell in the eight-cell battery.

Boeing’s pre-certification testing did try to evaluate the effect of an internal short circuit. It chose to do so with a test that punctured a cell with a nail to induce a short circuit.

“This test resulted in venting with smoke but no fire,” the NTSB reported.

But was the cell inside a closed battery compartment with 7 other warm cells at the time? Or even insulated to confine the released energy?
And was the charging system pumping 45 amps in throughout? :\

PAXboy

8th Mar 2013, 01:35

From the NTSB report linked earlier:
The Battery Monitoring Unit main circuit card and sub-circuit card do not contain nonvolatile memory (NVM), and none of the BMU data are recorded on the FDR.Well, there's one 'To Do' item.

I think that we can be glad that such a comprehensive document, set in plain language and with real photographs is publically available. I wonder if all countries do this when one of their own is in the frame?

Edmund
I think before the 787 is let loose again, a test flight might be made with the families of some of the executives on board.Good plan, start a petition. :D

vapilot2004

8th Mar 2013, 02:41

I think that we can be glad that such a comprehensive document, set in plain language and with real photographs is publically available. I wonder if all countries do this when one of their own is in the frame?

I agree, it was refreshing to see a detailed and relatively quick report out of the NTSB. As to your last statement, PB, the most insidious are not they of zipped lip but those that have a casual relationship with integrity and knowingly publish something less than honest.

denachtenmai

8th Mar 2013, 06:40

PAXboy
I wonder if all countries do this when one of their own is in the frame?
You should know the answer to this, living, as you do, in the spiritual home of De-Havilland:)

guided

8th Mar 2013, 09:33

I don't understand this from the report

1022:00 main battery is discharging
1022:53 main battery power switch is off

Was the battery switched off on purpose or did was it drained in just the 53 seconds?

Volume

8th Mar 2013, 10:28

So if the brakes are applied to a certain pressure and corresponding braking torque, they will maintain that braking until the actuators are driven in the opposite direction. This is a bit oversimplified...
What brakes the aircraft (what produces a break torque) is the force compressing the brake disks (and the coefficient of friction). What is defining the force is the ammount of compression by the spindle and the stiffness of the brake disk package. If the brakes are active, they wear and become thinner (just a little bit, of course), but the also get hot, and with the negative thermal expansion of carbon fibre they get even thinner, while the housing from metal expands at the same time. Given the same ammount of deformation (spindle is fixed), the compressing force and hence the brake torque will fade with use. How much strongly depends on specific numbers. So you may lose a significant amount of brake torque if you do not adjust the spindles, which means that without electricity, you will probably end up with less braking power than desired.

which of course still is a simplistic view of the issue...

rvusa

8th Mar 2013, 10:42

If you care to read the report the answer is on page 2, para 1, lines 8/9!
;)

WHBM

8th Mar 2013, 11:43

The fire came to the attention of the ground crew through the smoke permeating the aircraft and the electrics shutting down.

Is there no smoke/fire alarm in the E/E compartment ? Do we have smoke alarms in each readily accessible aircraft toilet, but not in inaccessible compartments full of high energy technical devices ?

Chris Scott

8th Mar 2013, 12:10

edmundronald

8th Mar 2013, 12:31

The NTSB has done a nice writeup.
The APU shutting down when its starting power supply goes down, the smoke evacuation being linked to the equipment on fire, the lack of diagnostic NVRAM are all systems integration issues.
The battery technology is in the end minor and easy to change, give or take the weight of a passenger, but it is to be feared that similar integration issues pervade the rest of the plane's design.

WHBM

8th Mar 2013, 13:11

The battery technology is in the end minor and easy to change, give or take the weight of a passenger...
But Boeing just won't entertain this. They have come up with all sorts of workarounds to avoid this. If that is their attitude to the prime cause of the fire, what is going to be their approach to the rest of all these issues now unearthed ?

Kerosene Kraut

8th Mar 2013, 13:13

With the planned april tribunal ahead the NTSB will prevent any fast FAA makeshift permit to fly for the hotbox concept. This whole thing will take more time.

sb_sfo

8th Mar 2013, 13:27

The NTSB can't prevent the FAA from doing anything, nor can they proactively force the FAA to do something. The FAA is the regulator, the NTSB is an independent agency with no regulatory power. The NTSB can name and shame, and that's about it.

toffeez

8th Mar 2013, 14:11

I can't believe Boeing is dumb enough to fly a quick fix which only passes the FAA after more than the usual number of free lunches.

If that happens I hope the NTSB has the guts to say "this is not safe enough".

badgerh

8th Mar 2013, 14:55

It seems a pity that the executive summary did not finish four words earlier. Omit "lithium-ion battery system" (Is that 3 words or 4??) and we would have some real sense:

The NTSB is also continuing to review the design, certification, and
manufacturing processes for the 787.

Momoe

8th Mar 2013, 15:05

VAPilot 2004,

Aviation safety has moved on a lot since the 70's, while it's understandable to have teething problems when introducing new technology, both the carriers and their passengers did not sign up to become Beta testers.

Boeing's solution wouldn't have been acceptable in 1960 let alone 2013, the more you read the report the worse it gets.

Boeing didn't design the plane to have a battery fire in flight, I'm also damn certain that their calculations are way off on the battery swap frequency, if there's a problem with the battery, resolve the problem so it doesn't occur.

Putting the damn thing in it's own incinerator case and touting this as a workable solution is a triumph of the bean-counters over Boeing's illustrious heritage.

TURIN

8th Mar 2013, 15:20

Does anyone know if the Aft E&E bay is accessible from the cabin, i.e., in flight? From Page 8 of the report:
"This compartment is located aft of the main landing gear and beneath approximately the third set of cabin doors (L3 and R3). The compartment is only accessible from the ground by a door in the aft cargo compartment and a set of doors in the airplane belly."

The second sentence is ambiguous on this point. Is it "only accessible from the ground"? Or "from the ground (only accessible) by a door in the aft cargo compartment and a set of doors in the belly"?

And how about the Forward bay?

The aft EE bay is only accessible when the a/c is on the ground.

Either through a hatch in the belly (this is the normal maintenance route).

OR

Via the aft cargo hold through a door in the partition wall between the aft cargo hold and the EE bay.
Of course if the hold is full of pallets/cans etc that is a no go.

The fwd EE bay is accessed either through a hatch in the lower fwd fuselage or from the cabin through a hatch in the floor. Ergo, it can be accessed in flight.

Chris Scott

8th Mar 2013, 15:22

Quote from FlightpathOBN (after photo, Feb 28th (http://www.pprune.org/rumours-news/505455-faa-grounds-787s-54.html#post7718259)):
"virtually ALL of the images of the 787 show the RAT deployed on ARR.."

My guess is that most of the photos will have been taken on acceptance flights. The RAT has to be tested, and it tends to be done towards the end of the flight, because of the buzz-saw noise (and maybe restrictions on other activities) once it is extended. That's what happens at Blagnac (Airbus).

Cows getting bigger

8th Mar 2013, 15:25

I have read this thread with great interest. A couple of thoughts:

It would be a very brave regulator that ignored the recommendations of the independent safety auditor. In the UK the CAA make great efforts in absolving themselves of any risk ownership and I can't imagine the FAA being any different.

I'm sure the battery problem will be solved one way or another. As others have said, the BIG question must be about the efficacy of the whole safety management process utilised in designing the aircraft. Boeing could be lucky and this event may be the only example of unsafe design, procurement or manufacture in the 787. On the other hand......

poorjohn

8th Mar 2013, 16:52

Cows: It would be a very brave regulator that ignored the recommendations of the independent safety auditor. In the UK the CAA make great efforts in absolving themselves of any risk ownership and I can't imagine the FAA being any different.In the US the NTSB makes recommendations. As an independent agency with its own body of expertise, the FAA sometimes does not follow them.

I'm sure someone will explain it better but I think the NTSB is decreed to be independent of improper outside influences and afaik does a good job of that. OTOH it seems to me that the FAA charter is not so saintly - its job is to keep airplanes flying safely, and not unlike other government agencies that touch on commercial interests it seems to have become more and more aligned with those interests over the decades.

This is the same body that, for instance, finds it difficult to mandate that our regional carriers hire well-trained pilots and pay them enough to assure they can afford a place to sleep at night and don't need a second job to raise their pay all the way up to our poverty level. I'll bet they're not having fun with this high-pressure situation - between a rock and a hard spot for them.

Kerosene Kraut

8th Mar 2013, 16:58

The NTSB announced to set up a public enquiry/hearing about topics from NiCad batteries to certification. This will ruin any possible quiet agreement beforehand. Smart move by Hersman if you want.

fgrieu

8th Mar 2013, 17:29

In their interim report, section 1.5.4, the NTSB reports having made Computed Tomography (CT) scans of both the APU battery that burnt, and "the main battery (that) was used as an exemplar battery for the radiographic studies". This sentence strike me: The CT scans for the main battery showed no anomalies outside the cells.
And, in the "Ongoing and planned investigation activities, this one: Document the results of the CT scans of the individual cells from the main battery.
Any interpretation of that?

inetdog

8th Mar 2013, 17:39

fgrieu:
Any interpretation of that?
To me, as I think to you, it suggests that they found what may be anomalies INSIDE the main battery cells.
Good catch!

saptzae

8th Mar 2013, 17:43

@fgrieu

Document the results of the CT scans of the individual cells from the main battery.

The Root cause - of the Primary failure (cell short) - remains undetermined, without any tangible progress apparent.

The state of damaged batteries precludes determination of the Root cause.

To look for clues in other batteries (across the fleet) seems to be a good bet.

vapilot2004

8th Mar 2013, 17:49

Aviation safety has moved on a lot since the 70's, while it's understandable to have teething problems when introducing new technology, both the carriers and their passengers did not sign up to become Beta testers.

It has thankfully, yes. My point was the hullabaloo slowly died down and the new technology (then NiCad) moved forward. I don't think it will be any different today.

Boeing's solution wouldn't have been acceptable in 1960 let alone 2013, the more you read the report the worse it gets.

I too question the certification process. Nothing turned up. These two incidents are apparently a complete surprise to the cosmopolitan group involved - the Japanese battery manufacturer, the French electrical system integrator, Boeing, and both the American and European regulators.

Boeing didn't design the plane to have a battery fire in flight, I'm also damn certain that their calculations are way off on the battery swap frequency, if there's a problem with the battery, resolve the problem so it doesn't occur.

Truth be told, the battery's case and surrounding structure were designed with a possible overheat and fire in mind. This was mandated by the FAA. Boeing, actually Thales, France, paid an enormous amount of attention to the volatility and other dangers associated with lithium battery technology and it was thought all bases were covered. As it turns out, something got round their collective thinking.

Your point about the multiple swaps is a good one. It was not so much a longevity issue, it seems there were problems that nobody understood and since the electronics and computer wizardry were given a pass, the remaining troublemaker left standing was apparently assigned to a series of failed battery packs.

I feel fairly certain the problem surely resides within either the battery or the charging-monitoring system. What else is there?

Momoe

8th Mar 2013, 18:23

There are aspects of the electrical system that aren't working as they should, the battery swap frequency makes me think that the Li-Ion infrastructure needs to be better understood before a solution can be implemented.

Is the battery QC that bad? I don't think so. There are other factors at work here which need to be understood.
Only when the fault is replicated consistently will it demonstrate that these factors are understood, hopefully this will pave the way to a passive solution rather than the incinerator on board proposal.

I haven't forgotten the UPS 747F which went down in Dubai with Li-Ion batteries as the suspected cause, also the Asiana 747F which went down in similar circumstances. If these were passenger flights maybe Li-Ion batteries would be viewed differently.

inetdog

8th Mar 2013, 20:43

Momoe:
I haven't forgotten the UPS 747F which went down in Dubai with Li-Ion batteries as the suspected cause, also the Asiana 747F which went down in similar circumstances. If these were passenger flights maybe Li-Ion batteries would be viewed differently.
Not necessarily. These Li-Ion batteries were carefully placed in secure blue boxes and monitored, which *should* have eliminated the earlier problems. They might have been viewed differently by the public, but I am not persuaded that the engineers and regulators would have acted any differently.

EastMids

8th Mar 2013, 23:07

The frequency of failure surely must be an issue. Whilst the regulators might be prepared to accept the better containment solution, are the 787's customers really going to do so, especially long term? How many times are 787s going to land somewhere with smoke coming out of vents or battery fluid dripping down the side, how many ETOPS diverts with hot batteries, and (even if the battery pack is a LRU) how many times will 787s be AOG for lengthy periods because there isn't a spare battery pack at some outstation, before airlines say to Boeing - fix the problem properly?

vapilot2004

8th Mar 2013, 23:26

Mids, I don't see the FAA clearing this aircraft for passenger service with just a containment option on the table. There must surely be at least a likely cause identified for the meltdowns before it can fly.

As stated in an earlier post, there are two possible culprits in my mind. Something in the battery manufacture or some bit of missed trickery in the computer coding or electronics boxes provided by Thales.

kilomikedelta

9th Mar 2013, 00:51

My guess is the software. It was probably written in C++. Computer code that crucial should be written in processor machine code. But maybe nobody knows that language anymore.

quentinc

9th Mar 2013, 08:29

The fact that the APU shutdown because a battery had failed seems odd. The APU is there to generate power and was running... Clearly the expectation of battery failure was low in the engineer's mind when the systems were designed. Later on, in testing and certification, the same assumptions must have been made, or this undesireable behaviour would have been caught before.

Now that we know that these batteries can and have failed... it might be an idea to think about and test, what other system are effected by the batteries going off-line...

Tu.114

9th Mar 2013, 08:49

Quentin,
it is not that uncommon for an APU to require a second source of power to run. This has been discussed in the other thread (http://www.pprune.org/tech-log/505695-787-batteries-chargers-45.html?) over at Tech-ops.

Even on the lowly DH8-300, switching off the main battery when running the APU (with no external power connected) would cause an instant APU shutdown.

quentinc

9th Mar 2013, 09:41

So its not a surprise.... Engineers have been designing systems, with the assumption that batteries are not going to fail. With the technology that we had... that was fine. Batteries didn't fail, so having a system that in this particular scenario, required the APU to run, to operate the vents, to control a fire... was fine.... because the battery wouldn't set on fire and go off line in the first place...

My point is that it is clearly not enough to simply insulate the batteries a little more and vent any fire out of the aircraft.... Thought has to be given to the implications of failure of batteries, that appears to have been a scenario not worth bothering about previously.

Walnut

9th Mar 2013, 09:51

The APU shut down when its battery failed because it needs an independant pwr supply to fire off its fire bottles if the unit (APU) catches fire. An APU frequently runs unmonitored on the ground.

programmerPax

9th Mar 2013, 10:10

As an experienced programmed with 30+ years exerience, writing anything in processor machine code increases the risk. Languages like C++, Ada, Forth et al, were deleveloped to both abstract the program away from the physical processor but to also allow the programmer to work at a higher level. The only time software is really required in machine code is when speed, critical sections and/or complete control over the hardware is required.

While at University studying Computer Science, one of my lecturers told us about his year sabbatical at Nasa working on Cat III landing projects. The problems they encountered were rarely the software being written in a high level language, but where two or more software processes made very sensible assumtptions (when viewed in isolation) "what if something goes wrong, do this...." actions, but when combined together made life terrifying for the poor pilot.

If software is to blame for these battery events, then it it will be down to two or more "assumptions" not lining up correctly.

Hi_Tech

9th Mar 2013, 10:27

The interim report has given a lot of points for discussion on info that was not available.
But I give below answers (as much as I know) for some of the questions raised by various, though some are irrelevant to this thread.

Land with locked wheels and no anti-skid?

Prior to landing brakes are selected on through the auto brake system. Pilot selects the deceleration rate depending on aircraft weight, runway length available, dry/wet condition etc. But the brakes are not applied till the air/gnd sensing circuit has sensed that the aircraft weight has come on wheels. The anti-skid system also plays a part in keeping the brakes released on most aircraft till that time. This is true on all aircraft from B747 on wards.

Was the battery switched off on purpose or did was it drained in just the 53 seconds?

The recording is actually of some one turning off the Main battery switch in the cockpit. It was probably done by the engineer to de-power the aircraft completely as there was a fire in one zone. Such action is normal.

The fact that the APU shutdown because a battery had failed seems odd

On most aircraft I know, APU fire protection is through the APU battery. So it could be same here, (I have not seen the WDM for this plane). You do not want to run an APU on ground without the fire protection. Do you?

Is there no smoke/fire alarm in the E/E compartment ? Do we have smoke alarms in each readily accessible aircraft toilet, but not in inaccessible compartments full of high energy technical devices ?

This aircraft and most Boeing types are fitted with a smoke detector in the duct that carries the cooling air out of the electronics bay. That way all the electronic boxes etc are monitored. It is like fitting a smoke alarm near the exhaust fan of a room than any one location inside the room. These equipment are force cooled, so this arrangement is possible.

quentinc

9th Mar 2013, 11:38

You do not want to run an APU on ground without the fire protection. Do you?

You are right. I don't want this but I also don't think its wise to have the smoke handling systems for the APU battery, require the APU to keep running... If that can't be achieved with the APU battery off-line... Last paragraph of page 34.... As I said... someone needs to think through the implications of battery failures.

Mark in CA

9th Mar 2013, 11:46

Here's another opinion piece on the Boeing 787 situation, and it says many of the things already posted on this forum. What's interesting is that the author comes from the financial industry, yet still reaches many of the same conclusions.

Annals of quantitative overconfidence, Boeing edition | Felix Salmon (http://blogs.reuters.com/felix-salmon/2013/03/08/annals-of-quantitative-overconfidence-boeing-edition/)

syseng68k

9th Mar 2013, 12:47

Mark in Ca:

How about: "Selective generalisations of the facts to support his case, from someone
who obviously has no idea what he's talking about, but may have his own agenda".

Sorry, but it needs to be said. There's enough scaremongering over this already...

Hi_Tech

9th Mar 2013, 15:21

quentec

I also don't think its wise to have the smoke handling systems for the APU battery, require the APU to keep running.

When Boeing conceived and designed B787 some of the legacy system design was almost same as the older Boeing planes. What we have on this aircraft is not a smoke evacuation system, but an equipment cooling, by drawing air from the cabin by using a fan to blow the air through the electronic racks. This air is exhausted on ground to the outside. In flight this air which is warm, is ducted in to the cargo compartment to conserve the heat energy. A smoke detector is there only to divert this air when a smoke is detected in these ducts. In flight, by opening valves air and smoke is vented outside through the same port which is used on ground. Diff air pressure will do the job. No point in dumping the smoke in to the cargo.
This design is the same from B747 classic of 1960s design. When Boeing designed the B787 they had no idea that their battery will go up in smoke in violent fashion. They stuck to the legacy design as the battery fire was not in their mind then.
When APU shuts down, the venting also stops (on ground) as the Fan blowing the air will also stop, and there is no diff pressure. Functionally, I doubt if this vent duct can with stand a lithium overheated discharge. Now Boeing is coming out with a strong box and external venting. Details are unknown, and I am sure it will not be through the existing ducts which are very thin fiber material. It will require a re-design as well. watch this space.

fc101

9th Mar 2013, 17:07

My guess is the software. It was probably written in C++. Computer code that crucial should be written in processor machine code. But maybe nobody knows that language anymore.

and how would using x86 or whatever processor being used make any difference? What you'd end up with is a much harder job of writing code. As it is C/C++, PL/1, Ada etc have code-checkers, well defined, certified compilers, assertion libraries which make writing in these high(er) level langauges MUCH safer than writing at the level of bare metal.

syseng68k

9th Mar 2013, 17:48

language isn't the issue, since the language is simply there to express
a solution to a problem. After all, you want to program solutions to the
problem, not get a first in processor architecture :8. The more that the
problem can be expressed in high level structured form, the better and
assembler is just too low level and non portable to be of any use. It's also
much more bug prone and difficult to maintain.

Speaking as an ancient 6502 bod from 1977 vintage and one who still programs
things like startup code in assembler, I would much rather be programming in
C, but agree wholeheartedly that C++ is a step too far for any critical
embedded work, irrespective of how fashionable it is. There are good reasons
as well...

JohnMcGhie

9th Mar 2013, 23:54

@Turin:

My greater concern is not that these batteries catch fire, but that they fail! On a fly-by-wire aircraft, that gives a whole new meaning to the term "dead stick". Yes, I know almost everything else has to fail before this matters. But consider Sully's celebrated ditching:

He lost both engines. His APU was not running. If his batteries had failed, and his aircraft had been a 787, he would have had no flight controls. At all.
The 787 also has individual back up batteries for the three ACEs (Actuator Control Electronics-part of the fly by wire system) they are also Li-Ion. The 777 is similar.

According to Ben Sandilands, they nearly fried the Flight Control backup battery as well:Dreamliner crisis: JAL 787 was at risk of 2nd battery fire | Plane Talking (http://blogs.crikey.com.au/planetalking/2013/03/09/dreamliner-crisis-jal-787-was-at-risk-of-2nd-battery-fire/)

The Firebox would seem like a good idea, essential in my opinion, if you want to fly Li-Ion batteries.

But as I said before, my problem with Li-Ion batteries is not that they catch fire, but that they fail. I don't think Lithium Ion batteries are sufficiently reliable for safety-critical aviation service.

Cheers

JohnDixson

10th Mar 2013, 01:10

APU: Unsung hero of the engine world
Print
By: JOHN CROFT WASHINGTON DC 12:00 5 Oct 2010 Source: Flight

Auxiliary power units (APUs) do their dull and dirty work hidden away in aircraft tailcone compartments, unlike their turbine engine brethren connected to the wings or empennage.

On occasion however, the tables get turned.

On a bitterly cold Thursday in January 2009, the Honeywell 131-9A APU in the tailcone of a US Airways A320 that had just departed New York's LaGuardia airport came to the rescue after the aircraft struck a flock of geese. With both CFM56 turbofans damaged and the associated electrical generators eventually knocked off line, the APU during the final seconds of the ditching provided the power needed to keep the flight controls, displays and envelope protections in place to allow the pilot to touch down in the Hudson River in control and at the lowest possible airspeed.

dabrat

11th Mar 2013, 22:09

“This test resulted in venting with smoke but no fire,” the NTSB reported.

Boeing also consulted with other companies about their experience with the use of similar lithium-battery cells and “based on this information, Boeing assessed that the likelihood of occurrence of cell venting would be about one in ten million flight hours.”

Yet all of this analysis badly missed the mark. The probabilities proved to be off by a factor of 200.

The 787 that caught fire in Boston had logged just 169 flight hours.

And the entire operational fleet of 787s had logged a total 51,662 in-service hours, plus about 6,000 flight-test hours.

On the day of the Boston fire, the battery did not behave as predicted.

The battery’s power discharge was “not at the constant rate described by the Boeing or Thales documents and included large changes and reversals of power within short periods of time,” the report states.

The fire that day was small but intense.

Boston airport firefighters encountered heavy smoke in the passenger cabin and had to forcibly extract a smoking, hissing, popping, chemical-spewing battery from the belly of the plane.

Interviews by the NTSB revealed the firefighters did not know they were dealing with a lithium-ion battery, and they had great difficulty putting out the fire.

When Capt. Mark Munroe of the airport’s aircraft rescue and firefighting unit entered the plane, he “saw heavy white smoke billowing through the floor” of the passenger cabin.

After locating the fire inside the electronics bay in the belly of the airplane, firefighters entered the compartment through dense smoke and applied shots of Halotron fire extinguisher to the battery.

Lt. David Hoadley of the firefighting unit reported that “it seemed like the fire did not want to go out, it kept rekindling.”

Then the battery, in munroe’s words, “exploded.”

“Capt. Munroe heard the battery hissing still and pushing white smoke or steam. There was liquid sizzling over the sides of the battery and still heavy smoke conditions. ... The battery continued to hiss before exploding.”

Munroe related that “he felt something hit him in the neck while he was in the airplane,” and he was sent for medical treatment. “Something had burned his neck.”

Firefighters attempted to remove the battery from the jet but found the “quick disconnect” mechanism Boeing had included to allow the battery to be removed for maintenance was “melted and unrecognizable” and a metal plate was preventing access.

The firefighters cut away the metal plate, severed the battery wires, then “pried the battery loose with hydraulic spreaders and removed it.”

The battery was passed down to a firefighter and placed on the tarmac about 50 feet from the airplane.

100 minutes

The fire was declared under control an hour and 40 minutes after the initial notification.

Still, for all the intensity, no one was badly hurt and details in the report suggest it could have been worse.

NTSB investigators found no heat damage to any primary airplane structure — that is, any part of the airframe critical to flight.

Only the floor panel and carbon-fiber floor support material, which are considered to be secondary structure, “were found to be heat damaged beneath where the APU battery had been installed.”

And sitting on a rack above the battery that burned was a smaller lithium-ion battery, also supplied by Japanese manufacturer GS Yuasa, that is used to provide emergency power for the jet’s flight controls for 10 minutes or more “when no other electrical power is available.”

Investigators found the exterior of this battery had been “lightly scorched” by the fire below and noted its case had openings at the corners.

The firefighters suppressed the fire before it could spread to that second battery.

By Dominic Gates
Seattle Times aerospace reporter

Cyrano

11th Mar 2013, 22:19

FlightPathOBN

11th Mar 2013, 22:46

Boeing assessed that the likelihood of occurrence of cell venting would be about one in ten million flight hours.”

Aaarrrggh...everything the FAA does requires a statistical probably of 10-9 RELATED to itself, or the system.

Cell venting is a DEPENDENT variable, not independent, so the relationship is based on the CUMULATION of ALL events related to the battery, takeoff/landing, startup, charging/discharging, BMS, etc.

The issue is not 1 in 10 million flight hours, but a statistical relationship of all of the related events, and that the statistical average of ALL of the events to happen at the same time is 10 to the minus 9.

Of course, just so you are aware, your aircraft has a 10 -9 capability to stay within the selected RNP level... :ok:

edit..and really, quoting Gates???..

WHBM

12th Mar 2013, 07:52

Boeing Marketing V-P says the 787 proposal is a "permanent fix"

UPDATE 1-Boeing confident has permanent 787 battery fix-exec | Reuters (http://www.reuters.com/article/2013/03/11/boeing-idUSL1N0C33FP20130311)

They just don't get it, do they ? Having the Sales & Marketing department making the public pronouncements on the 787 fix. It's not only that many informed observers in the industry don't buy the proposal for one second (see above), let alone what the customer airlines think, but the overbearing dominance of the sales-led management over the design and engineering side was what got them into this in the first place.

What is surely needed is for the CEO and their competent electrical engineers (Boeing must have a few left) to stand up and say what the issue is, what the correction is, and all the technical detail needed for informed observers to understand what has been done. Instead we seem to have "Hey, it's fixed, I'm tellin' ya. Just gimme the certificate back so we can ship the iron and get the billing done ......".

barrieh

12th Mar 2013, 09:36

I'm a professional electrical engineer. I don't work in aviation. I have just read the NTSB Interim and I am horrified.

We (the overall engineering sector) have know for a long time that Li Ion batteries don't play well with others. They are have an *inherent* tendency to get hot and catch on fire if they are at all mis-treated (over-charge, over-discharge, sudden changes in rates of charge).

The standard solution is always to provide an old-style circuit breaker (or fuse) and an old-style over-temp breaker. By old style I mean "mechanical".

Boeing chose to use a "contactor" do both jobs, based on software calculations performed by the BCU. This is just plane (no pun intended) poor engineering. I have written thousands of lines of controller code in my career, I would never support a decision to protect a Li Ion battery with a breaker which makes decisions based on software (Even if I had written it).

This is a blatant failure of good engineering governance and a failure to apply good sense. (And putting a firebox around what is essentially a bomb still leaves you with a bomb, I don't know of any material which would have contained the fire which happened at BOS).

So I guess Boeing need a good, safe, sound, sensible solution. My suggestion is a slow-blow circuit breaker and an over temp fuse, placed in series. I know that this combination may limit the performance envelope of the battery but I think that's what needs to be done.

sky9

12th Mar 2013, 12:16

You would have thought that Boeing would have taken this down by now
Batteries and Advanced Airplanes - Boeing 787 Updates (http://787updates.newairplane.com/787-Electrical-Systems/Batteries-and-Advanced-Airplanes)

Their latest news statement is on the 9th February. Not bad for a website that is supposed to keep everyone up to date on the 787.
Latest Statements - Boeing 787 Updates (http://787updates.newairplane.com/Latest-Statements/)

EEngr

12th Mar 2013, 16:44

sky9 (http://www.pprune.org/members/7001-sky9)

Their latest news statement is on the 9th February. Not bad for a website that is supposed to keep everyone up to date on the 787.Which makes me wonder about this:

Boeing Marketing V-P says the 787 proposal is a "permanent fix"

UPDATE 1-Boeing confident has permanent 787 battery fix-exec | Reuters (http://www.reuters.com/article/2013/03/11/boeing-idUSL1N0C33FP20130311)
Its possible that this V-P may have gone 'off reservation' to soothe the customers. Or there is a deeper split within company ranks over the strategy for handling this issue. Its all just guessing from where I sit.

Boeing always liked to present a unified face to regulators, the press, customers, etc. This might be one reason why we are not seeing the breadth of investigation that I'd expect on this topic. They can't have multiple teams of engineers pursuing various hypothesis. That would look like uncertainty. And that could undermine their image as the ultimate technical authority for all things flying.

One way or another, rest assured that Boeing is expending quite a bit of energy to maintain their public image and legal liability. Sadly, probably a lot more than their engineering budget.

vapilot2004

12th Mar 2013, 17:46

The surprising thing to me is the battery, made by a Japanese company, the charging system electronics, made in Arizona USA under the direction of the French company Thales, who is in turn in charge of power electronics for the 787, have all never been fully tested as an integrated package.

Word has it the NTSB, Boeing, Thales and the rest of the gang now have a bench setup where all the various bits will be wired together and put through the paces in hopes of finding what went wrong.

Was it battery abuse caused by or ignored by improper, inadequate, or shortsighted computer programming electrickery? That's where my money is.

WHBM

12th Mar 2013, 17:55

Boeing always liked to present a unified face to regulators, the press, customers, etc. This might be one reason why we are not seeing the breadth of investigation that I'd expect on this topic. They can't have multiple teams of engineers pursuing various hypothesis. That would look like uncertainty. And that could undermine their image as the ultimate technical authority for all things flying.
No, that's just a PR perspective of the world. Only one face (their own, approved, one of course, which makes the PR team feel important). But in reality, if you can't get to the bottom of the situation, as here, it's actually good to see one team trying to recreate it to see if there's a basic flaw, another designing and testing a conventional battery solution, another doing the firebox, and then all coming up with the pros and cons, and the top management making the right choice between them. The customer airlines don't want marketing-autospeak, they want whatever the right engineering solution is.

Nobody here wants Boeing to go down an inappropriate path, it is so disappointing that the general feeling is that they are doing so. I really can't see any professional in the business going ya-ha-ha if they drop back to a previous generation of battery. OK, it didn't work out, right fix applied, on we go. Big boys stuff.

Momoe

12th Mar 2013, 19:18

Like the bench test idea, providing it accurately reflects the actual operating conditions. I also hope the FAA is invited so that all relevant parties can have input, although I suspect that the NTSB and FAA won't be buying each other lunch.

There's probably scope for rerunning some of the previous tests to see if the results are the same, be a tad interesting if the test rig throws up different results for tests carried out by the individual suppliers.

In fairness, all suppliers should have tested to known criteria and the results will be on record.

Just glad that there's some progress.

FlightPathOBN

12th Mar 2013, 19:20

Its OJT...

(not On the Job Training)

On the Job Testing....

HighWind

12th Mar 2013, 20:38

Barrieh,# 1232
I'm a professional electrical engineer. I don't work in aviation. I have just read the NTSB Interim and I am horrified.Quite understandable..

We (the overall engineering sector) have know for a long time that Li Ion batteries don't play well with others. They are have an *inherent* tendency to get hot and catch on fire if they are at all mis-treated (over-charge, over-discharge, sudden changes in rates of charge).Yes, and some some of them might even fail even if they are operated within specification.

The standard solution is always to provide an old-style circuit breaker (or fuse) and an old-style over-temp breaker. By old style I mean "mechanical".

Boeing chose to use a "contactor" do both jobs, based on software calculations performed by the BCU. This is just plane (no pun intended) poor engineering. I have written thousands of lines of controller code in my career, I would never support a decision to protect a Li Ion battery with a breaker which makes decisions based on software (Even if I had written it).I don't completely agree.
A mechanical circuit breaker is a reliable component, and would be the first choose for sort circuit and thermal overload protection.
But circuit breakers can fail, and nobody would detect it, and I have hard about several fires in my industry due to malfunctioning circuit breakers. (From a leading European manufacture)

If you really know what you are doing, a better protection can be achieved by contactors, and electronics. It would be possible to design a system that is fault tolerant, and have selftest to prevent dormant faults.

cldrvr

12th Mar 2013, 20:42

AP just reported the FAA signed off on Boeings proposed plans for a "fix", I have no further details.

Finn47

12th Mar 2013, 20:47

Seattle Times article here:

FAA gives OK to 787 test flights for battery fix | Business & Technology | The Seattle Times (http://seattletimes.com/html/businesstechnology/2020542493_787faaxml.html)

Momoe

12th Mar 2013, 20:52

Official

Link to FAA web
Press Release – FAA Approves Boeing 787 Certification Plan (http://www.faa.gov/news/press_releases/news_story.cfm?newsId=14394)

DozyWannabe

12th Mar 2013, 21:33

language isn't the issue, since the language is simply there to express a solution to a problem. After all, you want to program solutions to the problem, not get a first in processor architecture :8.

+1

As long as the language can be broken down into predictable blocks of assembler, it's not a problem. Most of the issues one runs into with compiled languages has to do with the libraries used, not the language itself.

Real-time coding is a very specific discipline that is at best only obliquely comparable to the processes used by the rest of us mere mortals!

Speaking as an ancient 6502 bod from 1977 vintage

Which means you've been around and working at least as long as the processor. I wonder what the world would have been like if Jack Tramiel hadn't inadvertently scattered that team to the winds...

barit1

13th Mar 2013, 00:47

Investor confidence is reflected in Boeing stock price of $84.16 -- a five-year high. :eek:

fgrieu

13th Mar 2013, 07:19

Quoting the FAA
Press Release – FAA Approves Boeing 787 Certification Plan (http://www.faa.gov/news/press_releases/news_story.cfm?newsId=14394)

> The battery system improvements include a redesign of the internal battery components to minimize initiation of a short circuit

Seems good news to me. Wish we had details on that one. I'm ready to swallow the whole plan if it solves both a probable cause of the incidents, and the most damaging consequences of a fire, that will remain conceivable with Lithium-Oxyde chemistry.

Full disclosure: I'm an engineer, there's electrical engineering written on my diploma, but I made most of my professional life in electronics applied to systems where "security" means resistance to hacking.

peter we

13th Mar 2013, 08:00

FAA gives OK to 787 test flights for battery fix | Business & Technology | The Seattle Times

FAA says its an improvement to the battery system, not a fix.

The redesign has been approved for testing, a design that should been used from the start.

Doesn't mean the 787 is much closer to flying with paying passengers, for that they have to identify the problem.

ozaub

13th Mar 2013, 09:53

From Press Release – FAA Approves Boeing 787 Certification Plan (http://www.faa.gov/news/press_releases/news_story.cfm?newsId=14394) the good news is:
1. “The plan establishes specific pass/fail criteria, defines the parameters that should be measured, prescribes the test methodology and specifies the test setup and design. FAA engineers will be present for the testing and will be closely involved in all aspects of the process.” AND
2. “The certification plan is the first step in the process to evaluate the 787’s return to flight and requires Boeing to conduct extensive testing and analysis to demonstrate compliance with the applicable safety regulations and special conditions.” All Special Certification Conditions must be met. Put simply that mean batteries must not burn, except possibly once or twice during the lifetime of the entire 787 fleet. If batteries do overheat or burn, any fire must be safely contained within the battery enclosure and any harmful fumes must be vented overboard.
All of this should have been proven much more cautiously first time around. In fact NTSB Airworthiness Report at http://www.ntsb.gov/investigations/2013/boeing_787/docket_documents/787_docket_doc13.pdf shows that certification assumptions and testing were woefully inadequate. Battery system components were tested in isolation, not even connected together! This time the job will be done better because there will be independent scrutiny.
My bigger concern is that NTSB gives us an insight into the inadequacies of Boeing self-certification but we have no idea what other tests were fudged elsewhere on the plane.

Golf-Sierra

13th Mar 2013, 13:11

I would expect any certification of this solution will at least involve taking the plane up to some high altitude airport, start one engine, pressurize the cabin to get the air flowing, short circuit the battery and wait 180 minutes or whatever ETOPS time is required and see what happens.

I would also advocate placing some kind of animals in the cabin to see if the exposure to fumes within that time frame will not prove hazardous - though I do hope there is some more humane way of assessing this particular risk.

The whole experiment could of course be filmed and then published on the web - actually seeing it work will convince people it can be trusted.

syseng68k

13th Mar 2013, 14:06

HighWind, #1239

If you really know what you are doing, a better protection can be achieved by contactors, and electronics. It would be possible to design a system that is fault tolerant, and have selftest to prevent dormant faults.

Circuit breakers can fail, but imho, an electronic solution driving a contactor
is not enough on it's own, since the contactor coil drive transistor itself can
fail short circuit, not to mention the possibility of other hardware or software
failures.

For such a safety critical design, belt and braces, using a normally open
contactor and a mechanical circuit breaker or hrc fuse, would provide
disimilar solution redundancy that covers either circuit failure.

I'm a bit disappointed about the lack of real meat in the proposed solution as
well, in that it's only discussed in general terms. The really sad thing is
that Boeing had to be kicked so very hard to get their act together and do the
job properly. The bean counters will still think they were right though. They
will probably see the whole exercise in terms of damage limitation and will
learn nothing from it at all :ugh:...

Momoe

13th Mar 2013, 16:02

Syseng68k,

Good post, especially last paragraph.

Boeing stock being at a 5 year high on the back of this is ironic!
There will be a bottom line to this, it's just not been written yet, let's see if the stock market is as enthusiastic then.

dervish

13th Mar 2013, 16:47

FlightPathOBN

13th Mar 2013, 17:52

Looks like it worked (for Boeing stock that is)

"Some analysts said the high-tech plane, which was grounded worldwide in January, might be flying passengers again as early as May, after the Federal Aviation Administration on Tuesday approved Boeing's plan to certify the battery system."

Boeing tests prompt analysts' upgrades, but risks still lurk - Yahoo! Finance (http://finance.yahoo.com/news/boeing-tests-prompt-analysts-upgrades-170933043.html)

RobertS975

13th Mar 2013, 21:26

Not exactly sure what the fix is here... but assuming that the batteries are enclosed in some kind of fireproof "safe", what kind of added weight do we foresee here? Is any extra weight simply going to cancel out the weight savings of these batteries in the first place?

FlightPathOBN

14th Mar 2013, 00:48

The following are the markups to the “revised” FAA Special Conditions:
In lieu of the requirements of 14 CFR 25.1353(c)(1) through (c)(4), the following special conditions apply. Lithium ion batteries must be designed and installed as follows:
(1) Safe cell temperatures and pressures must be maintained during any foreseeable charging or discharging condition and during any failure of the charging or battery monitoring system not shown to be extremely remoteimprobable. The lithium ion battery installation must preclude explosion in the event of those failures. (working group to refine).
(2) Design of the lithium ion batteries must preclude the occurrence of self-sustaining, uncontrolled increases in temperature or pressure. (this may be met with requirement (1) - working group to refine).
(3) No explosive or toxic gases emitted by any lithium ion battery in normal operation, or as the result of any failure of the battery charging system, monitoring system, or battery installation not shown to be extremely remoteimprobable, may accumulate in hazardous quantities within the airplane. (this may be redundant with (1)).
(4) Installations of lithium ion batteries must meet the requirements of 14 CFR 25.863(a) through (d). (may also need to include parts 23, 27, & 29).
(5) No corrosive fluids or gases that may escape from any lithium ion battery may damage surrounding structure or any adjacent systems, equipment, or electrical wiring of the airplane in such a way as to cause a major or more severe failure condition, in accordance with 14 CFR 25.1309(b) (also 23, 27, & 29) and applicable regulatory guidance. We may want to give other means of compliance such as venting gases off-board, containment enclosure, etc.
(6) Each lithium ion battery installation must have provisions to prevent any hazardous effect on structure or essential systems caused by the maximum amount of heat the battery can generate during a short circuit of the battery or of its individual cells. NOTE: Need to add a requirement to report maximum temperature reached during the RTCA/DO-311 Short circuit test. The equivalent UN 38.3 short circuit test states that testing occur at 55 deg C. DO-311 2.3.12 – External Short Circuit With Protection Disabled: states to report maximum temperature.
Test is run at 23 deg C. (7) Lithium ion battery installations systems must have a system means to control the charging
rate of the battery automatically, so as to prevent battery overheating or overcharging, and,
(i) A battery temperature sensing and over-temperature warning system with a means for automatically disconnecting the battery from its charging source in the event of an over- temperature condition, or,
(ii) A battery failure sensing and warning system with a means for automatically disconnecting the battery from its charging source in the event of battery failure.
(8) Any lithium ion battery installationsystem whose function is required for safe operation of the airplane must incorporate a monitoring and warning feature that will provide an indication to the appropriate flight crewmembers whenever the state of charge of the batteries has fallen below levels considered acceptable for dispatch of the airplane. (this is a new requirement that is applicable to Li-ion batteries/systems).
(9) The Instructions for Continued Airworthiness required by 14 CFR 25.1529 must contain maintenance requirements for measurements of battery capacity at appropriate intervals to ensure that batteries whose function is required for safe operation of the airplane will perform their intended function as long as the battery is installed in the airplane. The Instructions for Continued Airworthiness must also contain procedures for the maintenance of lithium ion batteries in spares storage to prevent the replacement of batteries whose function is required for safe operation of the airplane with batteries that have experienced degraded charge retention ability or other damage due to prolonged storage at a low state of charge. (this requirement is already required to meet compliance to 1529).

Willoz269

14th Mar 2013, 02:13

So correct me if I am wrong please, but they still dont know what the cause is (and probably never will), so the "fix" from Boeing is to "contain" a runaway battery, ie contain and released fluids and thermal damage inside a stronger box, not stop it from happening in the first place, am I correct?

ozaub

14th Mar 2013, 03:57

Willoz269; put simply the battery must not burn except perhaps once or twice during entire life of 787 fleet. If battery does overheat or burn, fire must be contained and emissions safely vented. Of course Boeing was supposed to comply with all of that in the first place. NTSB report already reveals some rash assumptions and skimpy testing that led Boeing to self-certificate a dangerous battery system. Better luck next time!

vapilot2004

14th Mar 2013, 05:36

Standard practice!

Certainly not good practice, is it?

Willoz269

14th Mar 2013, 05:37

Thanks ozaub, amazing it took a kick in the pants before they did the correct thing. It is still concerning that such a "rare event" will remain unresolved for the time being.

vapilot2004

14th Mar 2013, 05:43

Willoz, I find it rather hard to believe as well. I am hopeful the bench testing of the system will turn something up. Meanwhile, I find it unconscionable that the battery and computerized charging/monitoring electronics in this aircraft could be re-certified without finding the problem that caused the meltdown. Surely there will be no FAA stamp of approval without discovering the flaw(s) in the system.

inetdog

14th Mar 2013, 06:41

ozaub:
... skimpy testing...
Are you implying that driving a nail through a single cell in open air is not just as comprehensive a test as doing the same while it is in a closed box with other cells and connected to the charging unit? Boy you are picky!

dfstrottersfan

14th Mar 2013, 07:48

Willoz269
"So correct me if I am wrong please, but they still dont know what the cause is (and probably never will), so the "fix" from Boeing is to "contain" a runaway battery, ie contain and released fluids and thermal damage inside a stronger box, not stop it from happening in the first place, am I correct? "agree amazing conclusions. What about pressure build up in the containment should the worst occur? And at that point you don't have the battery. I don't see how this helps half way across the Pacific or Atlantic.

green granite

14th Mar 2013, 08:18

So, are Boeing going to have to prove that the new container will work at 40,000ft empirically, or will the back of a fag packet calculations be accepted?

The thought of a trial set up to deliberately abuse the battery so that thermal runaway occurs in flight is an intriguing one.

Baron 58P

14th Mar 2013, 08:38

Having flown below FL300 in propeller driven aircraft for most of my life I have seen St Elmo in all his glory, many, many times, and on occasion have listened to, and seen him, on the radio and other instruments. This lead me to wonder whether static electricity build up and/or magnetic induction could not have played a role in the 787 saga. In an aluminium can we have never had any problems but I remember that Beechcraft had some issues in isolating their avionics in the first plastic pusher that they built in the 1980s. Both static buildup and strong military radar caused some problems, if my memory serves. Any thoughts from the specialists?

cockney steve

14th Mar 2013, 10:02

I don't see the containment kludge being an issue. the outlet of the container could have a 2-way valve,,, venting out if internal pressure raises above standard and normalising (venting inward)when the aircraft drops below cabin-altitude oressure. the vent could discharge into a simple baffle-trap (think sink-waste) and final discharge could be arranged tat the tip of the tail-cone.
the sales-goons could promote this feature as "jet augmentation" to get you to safety quicker,if the battery failed :} any fluids not caught by the trap would discharge into the slipstream clear of structure. (maybe a hazard on the ground, but you can't have everything on the wish-list when bodging!

As these "standby" batteries are clearly NOT just that, the 2 controllers could "talk " to each other....should ground-staff over-discharge* either battery, the other could automatically start the APU which would then recharge BOTH to meet despatch requirements.....
*(over-discharge means reduced reserve BUT STILL ABOVE ON-BOARD RECHARGING-LEVEL.
back to battery construction......the coiled,"swiss-roll" method would still suffer similar stresses to folded construction...plates swelling would pressurise the seperator-membrane, shrinkage leave voids. linear expansion would "shuffle" them ,one agains another "wiping" the paste into uneven clumps....not saying this doesn't happen with present folded-construction, but simply restating my opinion that wound circular cells have weaknesses as well.

many posts back, i suggested,- each subcell in a thermal/electrically insulating pot tails of fusible material connecting to an internal busbar to main-cell stud.
thus, any individual subcell going T.U. would self-isolate allowing the cell to carry on delivering full voltage at 2/3 capacity.
An aditional safeguard would be to make the inter-cell straps as fusible-links....the problem there is that current sufficiently high to melt them would mean the battery was already unserviceable , so this would be s "stable-door" action.

Every sub-cell should be monitored...24 delicate devices linked together with the only control being on batches of 3 ,doesn't and hasn't worked.
Any of the millions of model-aircraft and Heli. hobbyists, who ,as a matter of course, run Lipo's to the edge, could have told the boeing bean-counters and engineers that their design was fatally flawed. (not to mention the cellphone and laptop manufacturers who'se products are used by totally untrained and non-technical consumers.....other than ONE recall, BILLIONS of active-service hours...and they don't charge 16K for a laptop-battery, charger and control-system!

IMHO, this is another short-term kludge to get the revenue rolling again before the liability takes them down.