FAA Grounds 787s

[Lyman]

And the 787 has two genset per side. That means at least two will be available, plus the RAT. When is 'redundant' beyond the pale?

Did Boeing 'miss' pushing for elimination of the standby power rule? Could they simply apply for offline Battery? Did they bite off a bit much in 'sampling' Lithium technology? Or did FAA deny such a proposal?

If batt is standby, why can't it be isolated in flight, even thirty minutes prior to and post flight?

ANA and JAL problems happened at TO and post parking. This problem may not be as critical as it might have seemed....

"INERTING" the batteries as part of the solution? It does say "STANDBY" in the regs.

Maybe someone who is not "uneducated" could respond?

[DaveReidUK]

Adding 200lbs to the OEW of a commercial airliner is not hugely significant.

I suspect you have never sat on either side of the table in an airline/manufacturer negotiation, or indeed in a design review meeting.

Weight always comes at a cost.

[Lyman]

Absolutely. 200 Pounds is a seat. The argument will not be, "You will not have a full aircraft every time, so we'll just discount its elimination..."

It will be, "That seat is five hundred dollars iost in revenue per leg."

"And that is two hundred thousand dollars every year...." conservatively...

[harpf]

Drom what I know of

All MC (small) batteries are made in China, Larger batteries(Car, Truck) are still made in the USA

[harpf]

Cost of 200lb

x 20 years 2M/200 rule of thumb, serveral $1,000 per / pound is what will be paid to get a pound out of a large aircarft (per aircarft). Or 1M could invested in engieering, to get a pound out of new deisgn were several K will be produced. So if 200 pounds of batteries = 50M in egeering and 10K per aircraft is no brainer to go for it.

[toffeez]

"I suspect you have never sat on either side of the table in an airline/manufacturer negotiation"

I did exactly that for several years.

[Golf-Sierra]

Is there someone her more knowledgeable who might be able to answer this question:

Is it usually the case that there is just one type of battery fitted across a particular type of airliner? Would this differ by version (i.e. also say a -800 vs. a -900) and by customer spec?

What I am driving at is that it would be very shortsighted of the manufacturer to build a charger compatible with only one specific battery type - be it chemistry or capacity. So perhaps retrofitting a different type of battery as an interim measure with weight penalty is a straightforward option?

I presume what Boeing is struggling to do at the moment is work out what actually did go wrong as the issue might not be in the battery itself.

[WHBM]

Originally Posted by Lyman

Absolutely. 200 Pounds is a seat. The argument will not be, "You will not have a full aircraft every time, so we'll just discount its elimination..."

It will be, "That seat is five hundred dollars iost in revenue per leg."

"And that is two hundred thousand dollars every year...." conservatively...

Indeed. But that's just a negotiating ploy, which, presuming Boeing do have some aeronautical professionalism left, they should be able to competently rebut. Of course, the manufacturers have only themselves to thank for this perception that seat-mile costs are the be-all and end-all of life, as if every seat on every flight 24x365 can be filled with revenue pax at full fare (and, following on with the Boeing 787 marketing guff, as if there is no potential market any more for anything under 7,000 miles range - I wonder what they make of All Nippon using their 787s on domestic flights !)

[toffeez]

To put the weight issue into perspective ...

Between October 2005 and August 2008 the Manufacturer's Empty Weight of the 787-8 increased by 12500 lb.

[DaveReidUK]

the manufacturers have only themselves to thank for this perception that seat-mile costs are the be-all and end-all of life

I've never come across an airline that laboured under that misapprehension. If they did, they would all be flying A380s. There are some circumstances when SMC is the most relevant metric, and other circumstances where aircraft-mile cost matters more.

That said, almost all airlines calculate their yield on a seat-mile/passenger mile basis.

[Jando]

Originally Posted by Sober Lark

... I'm finding it difficult to understand why the aircraft had to be grounded by the FAA rather than pilots or their representative bodies taking the initiative and refusing to fly them first.

Please note that - although many posters here only talk about the FAA - half the fleet was already grounded by their respective operators before the FAA grounded it.

[Sober Lark]

Thank you Jando

[Temp Spike]

What's the big deal with this Lithium-Ion battery? Don’t they have a Liquid Ni-Cad certified to replace it? Type Certificate Data Sheets? What a dumb idea to utilize a new concept battery without a ready replacement.

TCDS - T000215E

Lit Bat - Special Conditions - 25-359-SC

Any Body have 25-359-SC details?
I can't find it.

[Chris Scott]

APU Start, and ETOPS

Quote from cod liver oil:

“Power source for B787 APU starting may be airplane battery, a ground power source, or an engine-driven generator.
Wouldn't engine-driven generator be used as primary power source for APU in-flight lightup?”

Probably not. I cannot quote the ETOPS/EROPS requirements, but suspect one of the scenarios they address is likely to be that of complete electrical-generation failure. That MAY mean that the ability to start the APU is mandatory for some or all ETOPS legs. I doubt it would be acceptable to rely on the RAT and its limited generation capability to provide essential services for several hours (although I stand to be corrected).

However, as an interim measure, it might be acceptable to start the APU as a pre-emptive measure prior to commencing the part of the sector where the ETOPS rules apply. If the APU failed to start (due to cold-soak, or whatever), you would have to divert somewhere. So it might make sense to leave it running on departure (off-load), and not shut it down until the ETOPS leg has been completed. The fuel-flow on an idle APU at high altitude is relatively modest.

FOOTNOTE
Wouldn't it be nice to have full schematics of the B787 electrical systems in the public domain, nearly 18 months after this civil aircraft entered service? In April 1988, when we started airline ops on the cutting-edge A320, no one put any pressure on line pilots to treat the contents of the FCOM as sensitive commercial information. Why is Boeing so shy of divulging its engineering achievements?
In the present circumstances, public rumour and speculation becomes all the more rampant when hard facts are so thin on the ground.

[Rory166]

Weight penalty

There do seem to be some wild figures being mentioned in this thread with regard to weight penalty. What we do know for a fact is that the 8 cells used weigh 22 Kg in total. Now multiply that by whatever factor you have for the existing approved technology subtract 22 and you have the weight penalty.

My fear in this instance is that the very fact of the approval process has in this case led to the use of a fundamentally less safe chemistry because it is already approved for aerospace use. The assumption being that the numerous fires that have occurred with LiCo batteries are down to careless use and this would not happen in aviation.

There can be no doubt that the charging arrangements include individual cell voltage monitoring and temperature monitoring seems most likely.

I think the idea mentioned in a much earlier post of isolating the battery during flight has merit as a wokaround solution. After all these batteries are only a standby and have negligible self discharge rates. So charge the batteries on the ground then switch off charging, continue to monitor cell temp and voltage during flight.

[DozyWannabe]

Originally Posted by Chris Scott

pressure on line pilots to treat [engineering documents] as sensitive commercial information

Are we sure that's the case here, or could it just be that the materials are a bit thin on the ground at the moment? Agree totally with your point though.

[Chris Scott]

Rory166,

The problem with banning battery charging in flight is that, for profitable long-haul operations, turnrounds are so short and infrequent, and flights so long...

[Chris Scott]

DozyW,

Am going partly on what TURIN wrote a few days ago.

However, there must be a fair number of grounded B787 crews at the moment, who are kicking their heels and presumably surfing the forums to see what is being speculated. Have you found something I've missed?

[TopBunk]

@Chris Scott

The following link has a basic overview of the electrical architecture in it. Worth noting the Boeing publication os from 2005, so it may well have changed since then!

B787 Systems and Performance

Hope that is of some use.

[Chris Scott]

TopBunk,

Thanks, I had that one. It does something to whet the appetite. A bit like Eiffel's sketch on the paper tablecloth...

Chris