FAA Grounds 787s
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The Japanese culture of what constitutes acceptable design and production risk was then infinitely more refined than anything contemplated by the U.S manufacturers.
history repeats.
I remember when Olympus introduced the Gastro-Camera to the world
Their engineering and attention to detail was amazing.
I have maintained from the outset that the GS-Yuasa product will be beyond reproach and i stick by that.
The failure lies in the interface with the aircraft and it's monitoring-charging system....the cells have been operated outside their safe limits.
Over a hundred changed-out batteries since release to service bear testimony to that abuse and Boeing's wilful denial until the smokescreen got too thick.
If the FAA turn it down, I would expect McNerney would have to resign. For this reason alone, I would have thought they would go to extreme lengths to ensure it was completely acceptable before it was submitted. But if the proposal, as currently understood, is accepted, then it seems the whole of the knowledgeable aviation community, let alone the customer airlines, are going to rise up against it.
Interesting times.
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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?
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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?
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I have maintained from the outset that the GS-Yuasa product will be beyond reproach and i stick by that.
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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?
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
Batteries and Advanced Airplanes - Boeing 787 Updates
Are there any other applications of the LVP65 cell on commercial aircraft or is this new territory for the manufacturer?
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
Last edited by deptrai; 26th Feb 2013 at 13:59.
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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 
Last edited by deptrai; 26th Feb 2013 at 15:01.
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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
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
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Ex Cargo Clown said:
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.
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 )
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Where are/were the pilots? Post #929
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?
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?
If two of the main drivers for the battery are APU start and brakes, why wasn't air considered?
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EEngr
I'm just waiting to see if the firebox solution, once signed off by the FAA, doesn't become the long term fix.
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.
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Why stop at LiMn? LiFePO4 is even more inherently safe and has lots of accumulated use experience in abusive situations.
Lithium cobalt oxide - Wikipedia, the free encyclopedia
Last edited by FlightPathOBN; 26th Feb 2013 at 21:32.
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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.