FAA Grounds 787s
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@syseng68k
Well, I did re-read your post of yesterday, and in the clear light of day I can't understand why I thought you had accidentally confused NC with NO. I have to stop posting at 3 in the morning-- time for the red face...
I did go back and read your #902 post again. At the time I read it rapidly, but I recalled then noting that your position was that the coil circuit of this contactor should be carrying current with the aircraft in service. This is the general practice, and there are good reasons for it.
In my comment about the latching (to hold the NC contactor open without continued coil current), I was aware that no one had pointed out this possibility, and wanted to explain that it was possible to operate the contactor arrangement without having it drain the battery. I may have left the impression I thought this was a great idea-- but to the contrary I am just trying to understand the design philosophy operating at Boeing.
At the time I wrote, I had just that day ferretted out information on the size of the two alternator-starters on the APU (not small); and just today I've further determined that there has to be a large DC load on the APU battery bus when the APU is running (not just starting). The contactor coil current was posted today on the Tech board (2.6 amps IIRC, holding I presume), noted as being enough to drain the battery in about a day. I don't know the amps of the large DC load, but it would be rather substantially more, I'd think.
Over on Tech, mm43 today also posted that he thought some form of contactor latching had to be involved, possibly on the overcharge end of the range as well, and perhaps some form of electric unlatching (perhaps if the supervisory board draw bleeds off excess charge?).
If you look at the schematic in the ntsb report, it's quite clear that the
contactor is drawn with normally closed contacts, which is the contactor state
with the coil / solenoid unenergised. While it may be latching to the open
state, there's no evidence for this and in fact, the contactor looks fairly
standard in that respect, but yes, it could be latching to the contacts open
state.
I originally brought this up in tech log, (#902), which might better explain why this isn't a very good idea..
contactor is drawn with normally closed contacts, which is the contactor state
with the coil / solenoid unenergised. While it may be latching to the open
state, there's no evidence for this and in fact, the contactor looks fairly
standard in that respect, but yes, it could be latching to the contacts open
state.
I originally brought this up in tech log, (#902), which might better explain why this isn't a very good idea..
I did go back and read your #902 post again. At the time I read it rapidly, but I recalled then noting that your position was that the coil circuit of this contactor should be carrying current with the aircraft in service. This is the general practice, and there are good reasons for it.
In my comment about the latching (to hold the NC contactor open without continued coil current), I was aware that no one had pointed out this possibility, and wanted to explain that it was possible to operate the contactor arrangement without having it drain the battery. I may have left the impression I thought this was a great idea-- but to the contrary I am just trying to understand the design philosophy operating at Boeing.
At the time I wrote, I had just that day ferretted out information on the size of the two alternator-starters on the APU (not small); and just today I've further determined that there has to be a large DC load on the APU battery bus when the APU is running (not just starting). The contactor coil current was posted today on the Tech board (2.6 amps IIRC, holding I presume), noted as being enough to drain the battery in about a day. I don't know the amps of the large DC load, but it would be rather substantially more, I'd think.
Over on Tech, mm43 today also posted that he thought some form of contactor latching had to be involved, possibly on the overcharge end of the range as well, and perhaps some form of electric unlatching (perhaps if the supervisory board draw bleeds off excess charge?).
Are "we" confusing battery bus and hot battery busses here?
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I recently did some work on a Japanese 360* tracked-excavator .
the boom could be shifted from it's central-position...control was a mechanically- latching relay- in essence, like a domestic pull-cord light-switch.
short pulse to change-over contacts..another short pulse to revert to previous state..... IIRC the relay was made in some Eastern-Bloc country, not noted for it's high-tech industries.
@ mickjoebill..... they claim they haven't the room ,or the weight- penalty is too high to add a third battery/ increase the capacity of the current two fitments /change to a more stable technology......
But they can find capacity for a glorifird Victorian steam-boiler!!
the boom could be shifted from it's central-position...control was a mechanically- latching relay- in essence, like a domestic pull-cord light-switch.
short pulse to change-over contacts..another short pulse to revert to previous state..... IIRC the relay was made in some Eastern-Bloc country, not noted for it's high-tech industries.
@ mickjoebill..... they claim they haven't the room ,or the weight- penalty is too high to add a third battery/ increase the capacity of the current two fitments /change to a more stable technology......
But they can find capacity for a glorifird Victorian steam-boiler!!
Old Engineer, #1505
I'm just a grumpy old engineer as well and didn't mean to offend, just to
clarify what I said.
I used to have the highest respect for aviation tech, but after the system
design issues exposed by the AF447 accident and the current 787 woes, i'm
really not sure anymore. How could Boeing, with such a long history of
technical excellence and doing it right get it so very wrong ?. First with the
battery subsystem and now it seems, the power panels. There are so many design
issues with the battery subsystem that should have been obvious to seasoned
engineers. It's so much less hassle to do it once, do it right, fit and forget.
The more worrying thing is that these issues are just those that have leaked
out. Who knows what other gotchas will be exposed as time goes by ?. Very,
very sad...
I'm just a grumpy old engineer as well and didn't mean to offend, just to
clarify what I said.
I used to have the highest respect for aviation tech, but after the system
design issues exposed by the AF447 accident and the current 787 woes, i'm
really not sure anymore. How could Boeing, with such a long history of
technical excellence and doing it right get it so very wrong ?. First with the
battery subsystem and now it seems, the power panels. There are so many design
issues with the battery subsystem that should have been obvious to seasoned
engineers. It's so much less hassle to do it once, do it right, fit and forget.
The more worrying thing is that these issues are just those that have leaked
out. Who knows what other gotchas will be exposed as time goes by ?. Very,
very sad...
Paxing All Over The World
syseng68k
Many possible answer are in this thread, you can read about:
Boeing are just more than lucky that no one has died, thus far.
How could Boeing, with such a long history of technical excellence and doing it right get it so very wrong ?
- the new CEO and his performance at previous companies.
- the CEO's preference to talk to office types not engineers
- moving the HQ 2,000 miles away from the engineers
- introducing a radical change of development strategy - with their newest and most complex aircraft with a multitude of new technologies. Rather than keep that at home with the expertise and move a lower risk project into the outsourcing world
- Their regulators probably believed that Boeing knew what it was doing.
- Bear in mind that companies (and Boards of Mgmt) that have been doing extremely well for some decades always presume that they know what they are doing and that - since it's gone well for 20 years, they must be very clever. So they can't make mistakes, can they?
Boeing are just more than lucky that no one has died, thus far.
I used to have the highest respect for aviation tech, but after the system design issues exposed by .....the current 787 woes, i'm really not sure anymore......There are so many design
issues with the battery subsystem that should have been obvious to seasoned engineers. It's so much less hassle to do it once, do it right, fit and forget....
issues with the battery subsystem that should have been obvious to seasoned engineers. It's so much less hassle to do it once, do it right, fit and forget....
I've seen comments that the large number of 787 battery failures are down to ground tug staff overusing the battery supply during towing (battery needed for the electric brakes), and it's all down to useless ramp crews. I seem to recall exactly the same being said about that DC-10 door, that ground crew should never be so stupid as to mislatch it......
Boeing noted that currently, 25% of their workforce is eligible for retirement,
Back in the old days, Boeing used to build furniture just to keep their skilled carpenters busy during downturns. And hydrofoils, windmills, paving equipment, software, etc., etc. Not because they thought they could do a better job than the incumbents, but to keep some income coming in to help cover their pay.
Back in the late '90s, we (at Boeing) were shown a graph of commercial aircraft production, Boeing vs Airbus. The Boeing production rates swung wildly as demand ebbed and flowed while the Airbus rates were a smooth ramp, heading upwards. Management was complaining about the expense involved with having to staff up every time their was an uptick in production. Their solution: Push that problem out the door to their supplier chain.
Now, with this 787 egg on their face and some recent screw-ups involving electromagnetic compatibility issues and portable computing devices, I'm wondering which engineers would want a career at Boeing in the future.
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Boeing now is a marketing corporation not an engineering establishment. The focus of the MBA's in management and on the board of directors in Chicago is solely to provide an increase in shareholder value with respect to time. Once the slope of that graph is negative, they will be golden parachuted and immediately hired by other corporations because they have 'management experience'. Engineering for the business schools is a fungible commodity. Practitioners of spin medicine are much more valuable.
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EE,
to me it seems like they are trying to push out the older more expensive people...
appears to me the Union is good with that as well, as there is a potential for 2 dues paying members for the price of one....
to me it seems like they are trying to push out the older more expensive people...
appears to me the Union is good with that as well, as there is a potential for 2 dues paying members for the price of one....
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There's a little more to it than that. The infamous "Applegate memo" which came from within Convair and explained the dangerous relationship between a cargo door latching failure, floor collapse and loss of hydraulics was actually withheld by Convair's own management, not MD's. Where MD were culpable was that they knew of the cargo door latching failure - in isolation - during their own tests.
EEngr, #1512:
Not forgetting, the need to keep critical *group* skillsets alive and within
the company, which can take years to build up. Perhaps a little
altruism as well, in terms of keeping the workforce in wages. Some companies
were and still are much more clued up in that respect...
Back in the old days, Boeing used to build furniture just to keep their
skilled carpenters busy during downturns. And hydrofoils, windmills, paving
equipment, software, etc., etc. Not because they thought they could do a
better job than the incumbents, but to keep some income coming in to help
cover their pay.
skilled carpenters busy during downturns. And hydrofoils, windmills, paving
equipment, software, etc., etc. Not because they thought they could do a
better job than the incumbents, but to keep some income coming in to help
cover their pay.
the company, which can take years to build up. Perhaps a little
altruism as well, in terms of keeping the workforce in wages. Some companies
were and still are much more clued up in that respect...
Last edited by syseng68k; 2nd Apr 2013 at 21:03.
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we (at Boeing) were shown a graph of commercial aircraft production, Boeing vs Airbus
EEngr: at the same time Airbus management was showing staff the same chart. The message: less hiring & firing means better qualified, more experienced, workers and superior quality for the customer.
Last edited by toffeez; 2nd Apr 2013 at 21:06.
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Back in the late '90s, we (at Boeing) were shown a graph of commercial aircraft production, Boeing vs Airbus. The Boeing production rates swung wildly as demand ebbed and flowed while the Airbus rates were a smooth ramp, heading upwards. Management was complaining about the expense involved with having to staff up every time their was an uptick in production.
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In theory all this obsession with weight and aircraft design is explained by the projection of carrying 1 extra kilo, or part thereof, per sector km, per annum, over the lifetime of the airframe and calculating the operating cost penalty in fuel etc of that extra weight, sorry, mass being the new buzzword for weight!
However, the sight of the slim Jack/Jaqui Spratt being robbed of hard currency at check-in, just because their baggage is 1 kilo over the airline limit, whilst the the blubber mountain behind them in the queue with "legal" baggage limit is allowed through unpenalised, is totally illogical if the same cost per kg/km rule is applied.
Maybe Samoan Airlines will start a trend, rapidly followed by M'OL, Squeezy and the rest?
One can discuss technical fixes til hell freezes over, viz big clunky switches, protections various against hot batteries, overloads, high drainage rates, essential power supplies and all the other tech stuff which seems to excite some of our profession.
Let's wake up and smell the coffee, or the acrid fumes of burning Li-ion batteries! This whole exercise, if not proposed by an EADS "mole" to scupper the 787 project, was undertaken to shave off the very last kilo of bare weight as required by the beancounters, who obviously don't have a clue as to the anthropometric weight {mass if you insist!} trend of the SLF we see daily and which will only get worse in the forseeable future.
Stop looking for exotic "techie" fixes, put in a decent set of type/time proven batteries, accept the penalty in operating costs over the lifetime of the airframes, which is probably limited anyway by the alleged delamination of the carbonfibre wing and put the whole thing down to bitter experience.
Whatever happened to the K I S S principle in aviation design? Is the industry being run by whippersnappers with the latest I-device but precious little commonsense when it comes to engineering? The lessons of AF447 and the design philosophy are still being debated and yet the USA's 'best' allows this sort of idea to pass the drawing board and get to the metal-cutting and prototype stage.
All I can say is, as an old-timer with a few professional flynig hours behind me, shame on you! The Comet, DC-10 and other designers must be turning in their graves if they only knew the direction their 21st century successors were heading, blinded by the arrogance which comes with overconfidence.
However, the sight of the slim Jack/Jaqui Spratt being robbed of hard currency at check-in, just because their baggage is 1 kilo over the airline limit, whilst the the blubber mountain behind them in the queue with "legal" baggage limit is allowed through unpenalised, is totally illogical if the same cost per kg/km rule is applied.
Maybe Samoan Airlines will start a trend, rapidly followed by M'OL, Squeezy and the rest?
One can discuss technical fixes til hell freezes over, viz big clunky switches, protections various against hot batteries, overloads, high drainage rates, essential power supplies and all the other tech stuff which seems to excite some of our profession.
Let's wake up and smell the coffee, or the acrid fumes of burning Li-ion batteries! This whole exercise, if not proposed by an EADS "mole" to scupper the 787 project, was undertaken to shave off the very last kilo of bare weight as required by the beancounters, who obviously don't have a clue as to the anthropometric weight {mass if you insist!} trend of the SLF we see daily and which will only get worse in the forseeable future.
Stop looking for exotic "techie" fixes, put in a decent set of type/time proven batteries, accept the penalty in operating costs over the lifetime of the airframes, which is probably limited anyway by the alleged delamination of the carbonfibre wing and put the whole thing down to bitter experience.
Whatever happened to the K I S S principle in aviation design? Is the industry being run by whippersnappers with the latest I-device but precious little commonsense when it comes to engineering? The lessons of AF447 and the design philosophy are still being debated and yet the USA's 'best' allows this sort of idea to pass the drawing board and get to the metal-cutting and prototype stage.
All I can say is, as an old-timer with a few professional flynig hours behind me, shame on you! The Comet, DC-10 and other designers must be turning in their graves if they only knew the direction their 21st century successors were heading, blinded by the arrogance which comes with overconfidence.
Does any else agrees that Boeing tried to do too many new things (composite, all electircs, outsourcing) at once on the 787 project and failed to co-ordinate them?
Each element individually is fine,managable and safe but all together put the company in a difficult position.
Rwy in Sight
Each element individually is fine,managable and safe but all together put the company in a difficult position.
Rwy in Sight
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That might be true, RWY in sight.
Yet, I myself have a feeling (I said "feeling", and I may well be proven wrong in the years to come, and should I say, I even wish to be wrong?):
I think that the underlying truth of this whole story is that we are witnessing that battery evolution is coming to its end. This because of the intrinsic limits of the involved electro-chemistry that have been underestimated.
In paralell to the problems in aviation (that will be solved by alternate existing technology at great expense and big loss of the dreamliner's performance) battery-based individual automobiles as means of mass transportation may prove to be another dead end.
We'll see.....
Yet, I myself have a feeling (I said "feeling", and I may well be proven wrong in the years to come, and should I say, I even wish to be wrong?):
I think that the underlying truth of this whole story is that we are witnessing that battery evolution is coming to its end. This because of the intrinsic limits of the involved electro-chemistry that have been underestimated.
In paralell to the problems in aviation (that will be solved by alternate existing technology at great expense and big loss of the dreamliner's performance) battery-based individual automobiles as means of mass transportation may prove to be another dead end.
We'll see.....
Paxing All Over The World
Certainly with regard to battery powered automobiles - very few consider them to be the long and wide solution. Whilst they can be great in cities, it is reckoned the fuel cell is the main game.
As to did Rwy in Sight's question: Certainly. They over reached themelves spectacularly. The company (it's Board of Mgmt) lost sight of the basics and thought they were cleverer than they were. But that is the long, long story of human beings. We have seen countless examples of this before in history and countless more will follow. Mostly, the gamble pays off but Boeing will be paying the price for this for a decade.
As to did Rwy in Sight's question: Certainly. They over reached themelves spectacularly. The company (it's Board of Mgmt) lost sight of the basics and thought they were cleverer than they were. But that is the long, long story of human beings. We have seen countless examples of this before in history and countless more will follow. Mostly, the gamble pays off but Boeing will be paying the price for this for a decade.
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think that the underlying truth of this whole story is that we are witnessing that battery evolution is coming to its end.
No, seriously I think we are just in the middle of a revolution in battery technology. And we aint see nothing yet. Maybe even battery powered passenger transport aircraft, recharged in 45 Minutes, will be the post mineral oil reality, in 20 years. At the moment this looks more realistic to me than hydrogen...
I don't think we are at the end of battery evolution, but if you consider
that all the push has been towards higher energy densities in smaller
and lighter packages, so is there increased potential for serious trouble
when something fails.
There will always be risk and the only way to mitigate the safety issues
is via the use of smarter battery management techniques...
that all the push has been towards higher energy densities in smaller
and lighter packages, so is there increased potential for serious trouble
when something fails.
There will always be risk and the only way to mitigate the safety issues
is via the use of smarter battery management techniques...