FAA Grounds 787s

[RR_NDB]

Teething or incompetence?

NWA SLF:

Pilots saving our engineering asses.

If the investigation concludes the Li Ion batteries were operating with excessive voltage each cell (> 4,2 V or so) you still will consider that is reasonable transfer the issue to the pilots?

In AF447 case do you consider reasonable the pilots received a non fault tolerant and non gracefully degraded aircraft after encountering ice particles disabling the illusory redundancy created by the design and "maintained" by the carrier and authorities?

Pilots are paid to work operating machines that give chances to them in the event of failures.

A subsystem (battery + charger) in a highly sophisticated and advanced plane presenting this consequences (threatening the program) with smoke, electrolyte spill (inside an electronic bay) fire (BOS), emergency landing (TAK) and evac, IMO is a SHAME.

A redundant and safe DC supply (charger + battery) is an "ancient subsystem" and failures like the ones occurred are unacceptable. Boeing, Yuasa or Thales grounded the Dreamliner creating a Nightmare for everybody involved with the issue.

Something is VERY WRONG. This is very basic: A DC supply (from gennies), a battery and a load (the plane consumption). Difficult to manage?

I hope for a charger issue. Hardware, software, whatever. And FAST!

[DaveReidUK]

No I think he meant what he said which was that the design REQUIRED these batteries.

When the electrical system had been designed (requiring something like 1 MW of power!) the high energy density provided by use of Li-Ion technology was the only system which could provide such power at a reasonable size and weight.

Semantics.

Yes of course aircraft designers always want to save weight and space, and Li-Ion tops the list on those criteria, but that's not the same as saying that the 787 could not have been built without that particular battery technology.

Of course hindsight is a wonderful thing ...

[green granite]

To be able to charge a battery from a circuit powered by that battery then you would have invented perpetual motion, aircraft batteries, like car batteries, are only there to power circuits until the engines are running after which the engine(s) generator(s) take over all the power requirements. With your laptop it's not the battery powering it it's the mains PSU.

Presumably these batteries have to be isolated from the buss by a blocking diode otherwise uncontrolled charging will take place which will cause the battery to overheat. Could it be that there are some nasty spikes on the buss that takes the blocking diode out?

[wooski]

most laptops power from both the Batt and Ac (not 100% of the time though). as the AC adaptor cant provide all the power required, eg a 65watt power brick cant provide full load to a laptop when the laptop is running at 100% and will also take power from the batt if available, if its not, then it will change the cpu/gpu to a lower power mode. If you run your laptop batt flat and plug in the charger, do something cpu/gpu intensive and you will notice the laptop will stop charging and use the full 65watts and then the batt as well (if there is any capacity) . So im guessing the 787 works similar, rather then float charging the li-on all the time , unless there is some special way to float charge a li-on.

any idea if they charge the batt from the 115Vac ? or from the 270Vdc ? on the 787 ? im guessing its easier(cheaper?) to covert from 115Vac to anything that the charger needs, rather then a DC to DC converter ?

[SaturnV]

New York Times article suggests 787s may not quickly be flying again.

Airbus executives have expressed sympathy for their rival’s current woes and said they were confident Boeing would get to the bottom of the problem. But some acknowledged that an extensive review of the battery technology could set off costly delays in Airbus’s rival program, the A350-XWB, which uses the same type of batteries and is scheduled to enter service in late 2014.

Problems with lithium-ion batteries in the aviation world are not new and have contributed to dozens of fires aboard airplanes in recent years. Cessna was forced to replace lithium-ion batteries on its CJ4 business jet with nickel-cadmium after a battery fire on the plane in 2011. The CJ4 was certified under special conditions similar to the 787’s.

http://www.nytimes.com/2013/01/19/bu...r.html?hp&_r=0

[Terego]

Here is another link from Ars technica on this issue:
Boeing’s Dreamliner batteries “inherently unsafe”

The issue to stress is that these batteries are impossible to put out because they generate oxygen when in thermal runaway. Hence the spectacular roman candle video of what they can do. The safe technology based on LiFePO4 is unfortunately going to result in an approximate doubling of battery weight according to a battery specialist I talked to about this. How much do the batteries of the 787 weigh, so what would be the 'added weight of the solution?

[keesje]

Dreamliner 787 battery fires burn FAA and media too

Dreamliner 787 battery fires burn FAA and media too

The FAA and media come out looking foolish or institutionally corrupt as the 787 issues force regulatory responses, because there are other major question marks over this airliner and its certification as safe.

Dreamliner 787 battery fires burn FAA and media too | Plane Talking

[hetfield]

As reported by the Wall Street Journal, the FAA outsourced one of the fundamentals of its responsibilities for testing and approving the batteries in the 787 back to Boeing, the maker of the airliner which it was supposed to be certifying as safe.

Unbelievable.....

[John Farley]

hetfield

unbelievable

I thought such practices were the norm. The FAA just does not have appropriate staff to enable it to do otherwise.

Bit like the NTSB who also have to pull in company specialists with many accidents.

[poorjohn]

If a battery can't be both charged and discharged, how can both my laptop and phone be on and under load when plugged in to charge and the battery still gets charged while the system is running?

Not to belabor the point but at a moment when your device is operating and the battery is being charged, the charger is doing all the work.

[KBPsen]

I thought such practices were the norm.

As does anyone with more than a superficial knowledge of the certification process. There is nothing new, special or unbelievable here.

Sandilands appear to be looking for publicity by artificial controversy.

[Lyman]

No one expects FAA to keep expertise on staff. Their use of Boeing staff is bizarre.

In commercial construction, the authority can require additional or adjunct expertise at will; it does so utilizing independent sources, to avoid obvious conflict. And the engineering is underwritten by the builder.

And it has been that way for years...

Nothing Boeing does is so mysterious or proprietary that they must become the authority on duty of care. Or what constitutes regulation, or best practice.

It is inexcusable in aerospace that it should be this way.

[sb_sfo]

some more detail about ANA trouble

Boeing 787 battery in Japan sprayed hot chemicals | Business & Technology | The Seattle Times

[hetfield]

How much did the FAA pay BOEING to do the job?

[RR_NDB]

Going deeper

wooski

So im guessing the 787 works similar, rather then float charging the li-on all the time , unless there is some special way to float charge a li-on.

We will go deeper to address the issue.

[Machaca]

Washington Post reports:

Overcharging of batteries likely culprit in Boeing 787 fires, aviation and battery experts say

see Tech Log for more details and discussion.

[RR_NDB]

Uncontained failures

sb_sfo

"... two inside the battery and two external, would prevent any serious battery incident."

With this degree of redundancy we may think she (batteries) are operating a little bit above safe levels (during recharge at BOS and TAK). I assume in both cases the Systems were recharging her. To higher current levels in Logan. (rear batt used to start APU and being fast charged by APU gennies)

This may lead to a much better scenario: No major design issues, no defective parts, just the need of tweaking. Critical devices normally presents this in their teething. A Li Ion battery is such.

Finger crossing.

[cwatters]

An investigator in Japan, where a 787 made an emergency landing earlier this week, said the charred insides of the plane’s lithium ion battery show the battery received voltage in excess of its design limits

This investigator may have inside information but I very much doubt anyone can tell the cause from just looking at photos of the burnt remains!

Overdischarge can also cause problems for some Li cells when it's next charged. This is just one of the things that the charging circuit will check (eg that it's not too empty to be charged safely).

NPO19897 :: NASA Tech Briefs

"..overdischarge can result in dissolution of a metal current collector in the anode of a cell, with consequent internal short-circuiting of the cell..."

[RR_NDB]

Single Main Battery Li Ion specs (same for APU)

Terego

How much do the batteries of the 787 weigh, so what would be the 'added weight of the solution?

There are 8 LVP65 cells inside a metal case with two protection circuitry in the battery. Ea cell 2,75 Kg (look for LVP65-MSDS.pdf at web).

Estimating: Around 60 pounds

[RR_NDB]

More benign scenario?

cwatters,

This is just one of the things that the charging circuit will check (eg that it's not too empty to be charged safely).

And additionaly, a tweaking of the algorithms is likely to be required to increase the reliability of the Battery System (Battery + management System)

This may explain severity of BOS incident and characteristics of TAK one. What was common to both? The battery type. (probably the management system too).

Excellent link you found