FAA Grounds 787s
Joined: Jan 2004
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From: london,uk
Unfortunately with the 787 the chance of battery thermal run away was considerably less than 1 in 10 million
Mitigating this is Boeing claim that most failures were due to over discharge (which is obviously impossible as its basic preventative circuity requirement). And the less strenuous charging/discharging could make a huge difference - but they would have to find some method to proving this theory with a lot of testing
Last edited by peter we; 23rd March 2013 at 15:27.
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From: Seattle, WA
FlightPathOBN
The article was specific in noting that these reductions are for personnel working on change incorporation for early-build airframes to bring them up to specification. As the number of those airframes needing said work is reduced, the need for staff is reduced as well.
Heck, the IAM themselves said the reductions were "nothing to be alarmed about" because the demand in other aerospace industries for those workers is so strong they should quickly find new positions.
"Boeing said Friday it will lay off some 800 machinists by the end of this year as workforce needs on its newest jet programs, the 787 Dreamliner and 747-8 jumbo jet, are reduced.
Company spokesman Doug Alder said that other reductions will be made through attrition so that the total number of positions cut this year will be between 2,000 and 2,300."
Company spokesman Doug Alder said that other reductions will be made through attrition so that the total number of positions cut this year will be between 2,000 and 2,300."
Heck, the IAM themselves said the reductions were "nothing to be alarmed about" because the demand in other aerospace industries for those workers is so strong they should quickly find new positions.
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From: East Midlands
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“For every battery in service we have a manufacturing record, so we know how each one of the cells behaved when they were tested. We know today which cells will not pass the screening tests and when they return from the fleet we will reject those cells.
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From: South Korea
Huh? They know they have substandard battery cells on their aircraft?
ManaAdaSystem
The statement in the Aviation Week artical is a bit vague but I think you are correct. It seems Boeing have a "manufacturing record" for all cells in service so they can tell which cells will not pass the new tests.
Last edited by Cool Guys; 24th March 2013 at 12:54.
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From: Effin' Limbo
Call me stupid, but I don't get it. Boeing encases the battery in a box and voila! It is magically not only safe, but also exempt from any requrement to actually, you know - work, since the box doesn't address it's reliability in any shape or form.
Last edited by Max Stryker; 24th March 2013 at 16:33.
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From: toofaraway
Max
Joined: Jan 2013
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From: UK
@peterwe:
That is mathematical nonsense. Let me just replace your numbers with people and it's easy to see how crazy that statement is.
"Over a hundred people have died in less than 100 years, which gives a 1:100 years failure rate. In the first 10 years of life that is a 1:10 chance of dying."
Over a hundred batteries have failed in 50,000 hours, which gives a 1:500 hours failure rate. Over a 10 hour flight thats 1 in 50, the chance of both batteries failing is therefore for 50x50=1:2500. All year flying with a 500 aircraft fleet means 70 dual battery failures per year. And 3500 single battery failures per year.
"Over a hundred people have died in less than 100 years, which gives a 1:100 years failure rate. In the first 10 years of life that is a 1:10 chance of dying."
Joined: Jul 2002
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From: 40N, 80W
... Boeing encases the battery in a box and voila! It is magically not only safe, but also exempt from any requrement to actually, you know - work, since the box doesn't address it's reliability in any shape or form. ...
There two separate problems.
One is the battery problem, and how to make it reliable.
The second is the enclosure, and how to prevent the battery from damaging the aircraft. The enclosure is not intended to contribute to the reliability of the battery. The other changes are intended to take care of the battery problem.
But now we have a third task; how to ensure that the stainless steel enclosure is itself manufactured, assembled, and maintained adequately.
Cunning Artificer
Joined: Jun 2001
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From: The spiritual home of DeHavilland
The battery is being so heavily modified it isn't the same battery any longer:
1. Improved cell manufacturing process
2. Additional testing of completed cells.
3. Larger cell relief vents
4. Ceramic heat shielding between cells and between cells and battery case.
5. New intercell link nuts
6. Reduced maximum charge voltage limit combined with increased minimum cell discharge voltage
7. Modifications to the battery internal electronic monitoring logic that monitors cell balancing, charge levels and temperature.
8. Modifications to the battery charger, to accommodate the revised charge/discharge figures.
Then we come to the containment box.
3mm thick stainless steel case with the lid held on by 52 bolts! Scheduled battery changes now become a two hour job. Is it necessary? Will the public be reassured by a modification that includes putting a part of the aircraft into an explosion proof container, or will they assume that an unacceptable risk of serious failure remains?
I think the answer lies in many of the above answers by those unaware of the actual situation. This whole thing has been and remains a pR disaster.
1. Improved cell manufacturing process
2. Additional testing of completed cells.
3. Larger cell relief vents
4. Ceramic heat shielding between cells and between cells and battery case.
5. New intercell link nuts
6. Reduced maximum charge voltage limit combined with increased minimum cell discharge voltage
7. Modifications to the battery internal electronic monitoring logic that monitors cell balancing, charge levels and temperature.
8. Modifications to the battery charger, to accommodate the revised charge/discharge figures.
Then we come to the containment box.
3mm thick stainless steel case with the lid held on by 52 bolts! Scheduled battery changes now become a two hour job. Is it necessary? Will the public be reassured by a modification that includes putting a part of the aircraft into an explosion proof container, or will they assume that an unacceptable risk of serious failure remains?
I think the answer lies in many of the above answers by those unaware of the actual situation. This whole thing has been and remains a pR disaster.
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From: back of beyond
@FASRP
Peterwe's method of analysis is valid (I haven't checked the numbers) if you assume a constant failure rate, which is typical in mid-life of most objects subject to failure - including people.
The failure rate typically follows a "bathtub curve" with a high initial failure rate, a constant and (hopefully) low rate in mid-life, and then another increase due to old age.
The initial failures are normally screened off by factory stress testing or burn-in - one would hope that the parts Boeing are using have been sufficiently screened. The old-age failures would be avoided by mandating replacement before the bathtub curve starts rising.
From a reliability point of view, what we're seeing with these batteries is either an unexpectedly long infant mortality period, an elevated mid-life failure rate, or a premature ageing: we don't have the numbers to plot the graph and determine which, but Boeing certainly does, and has probably covered these bases with the proposed actions (the other two that don't get much mention here, not the containment vessel which is there just to keep the FAA happy).
Peterwe's method of analysis is valid (I haven't checked the numbers) if you assume a constant failure rate, which is typical in mid-life of most objects subject to failure - including people.
The failure rate typically follows a "bathtub curve" with a high initial failure rate, a constant and (hopefully) low rate in mid-life, and then another increase due to old age.
The initial failures are normally screened off by factory stress testing or burn-in - one would hope that the parts Boeing are using have been sufficiently screened. The old-age failures would be avoided by mandating replacement before the bathtub curve starts rising.
From a reliability point of view, what we're seeing with these batteries is either an unexpectedly long infant mortality period, an elevated mid-life failure rate, or a premature ageing: we don't have the numbers to plot the graph and determine which, but Boeing certainly does, and has probably covered these bases with the proposed actions (the other two that don't get much mention here, not the containment vessel which is there just to keep the FAA happy).
Last edited by fizz57; 24th March 2013 at 18:15.
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From: Rio de Janeiro
That is certainly correct. Boeing has failed to accept culpability in any meaningful way, and insists there never was a major problem. Denial, regardless of the facts, probably is not an optimal response in a situation in which the outcome depends on good will from the party that grounded the aircraft. Upsetting the NTSB is not the same thing at all, since the NTSB has no regulatory function.
Boeing, by intransigence, has given a PR festival to anti-Boeing forces. I wish they were better at such issues. Is has not helped their case that they have announced layoffs more than once since the grounding, insisting they're unrelated.
My opinion of Boeing has become negative since these events, less for the events themselves than for their actions since the grounding.
Boeing, by intransigence, has given a PR festival to anti-Boeing forces. I wish they were better at such issues. Is has not helped their case that they have announced layoffs more than once since the grounding, insisting they're unrelated.
My opinion of Boeing has become negative since these events, less for the events themselves than for their actions since the grounding.
Joined: Jun 2008
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From: U.K.
DuraReady or EverCell, the difference is?
Blacksheep, Quote:- "The battery is being so heavily modified it isn't the same battery any longer"
So a "different" battery that still requires a 3mm stainless steel case?
Doesn't show much confidence in the redesign, does it?
So a "different" battery that still requires a 3mm stainless steel case?
Doesn't show much confidence in the redesign, does it?
Usual disclaimers apply!
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From: EGGW
Doesn't show much confidence in the redesign, does it?
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From: Quayside
so one presumes this new fix and 'pr' box has been designed and approved by the exact same engineers using the exact same technology and the exact same oversight as the previos design that everyone said was perfect?
have the same fixes been applied to both batteries or just the ones that caught fire last time?
every RC hobbyist on the planet knows lithium batteries are an accident waiting to happen
i just hope it doesn't take a 787 Helderberg before boeing wakes up
have the same fixes been applied to both batteries or just the ones that caught fire last time?
every RC hobbyist on the planet knows lithium batteries are an accident waiting to happen
i just hope it doesn't take a 787 Helderberg before boeing wakes up