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Old 28th Feb 2013, 14:01   #1061 (permalink)
 
Join Date: Dec 2001
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Quote:
engine bleed was reliable power source
Engine bleed is expensive to maintain, leaks are common and potentially dangerous. Interflug lost an Il-62 due to a bleed air leak causing a fire.
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Old 28th Feb 2013, 14:19   #1062 (permalink)
 
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The Interflug Il-62 crashed back then because of a leaky bleed air pipe crossing the little known cargo compartment between the engines burned through insulation and some electrical wiring which ignited some barrel of deicing fluid that was carried there (not permitted per regs). And all that led to a fire, loss of control, inflight breakup and loss of all lives.
The type received modifications afterwards.

ASN Aircraft accident Ilyushin 62 DM-SEA Knigs Wusterhausen

Last edited by Kerosene Kraut; 28th Feb 2013 at 15:54.
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Old 28th Feb 2013, 14:28   #1063 (permalink)
 
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Agree

Quote:
The RAT has absoulutely nothing to do with pressurizing the aircraft. It simply does not have the capability to power the CACs
It is like attempting to start your car with two AA batteries.
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Old 28th Feb 2013, 14:34   #1064 (permalink)
 
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Quote:
Engine bleed is expensive to maintain,
Only time will tell how expensive these CACs and power conversion equipment are to maintain.
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Old 28th Feb 2013, 16:23   #1065 (permalink)
 
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Kiskaloo,

Agreed, in that Boeing don't design batteries. They would have looked at the energy density values and at the design stage, Lithium-Ion would have been a no-brainer.

Yuasa's expertise in battery design is beyond reproach, however at this moment it's uncertain what caused the battery pack to ignite. While it may have been a faulty battery, we don't know if the cell spacing exacerbated the problem or if the charge/discharge algorithms were faulty or if it was an as yet unknown factor.

What is clear is that Boeing pretty much went all in on 'Electric plane' concept and this made the Lithium battery a commitment rather than a contribution.

I'm still slightly surprised that there were no indications of potential battery problems during the testing/flight testing regime, these normally take each system to the edge of the envelope, yet no issues reported?
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Old 28th Feb 2013, 17:08   #1066 (permalink)
 
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Kiskaloo,

Agreed, in that Boeing don't design batteries. They would have looked at the energy density values and at the design stage, Lithium-Ion would have been a no-brainer.

Yuasa's expertise in battery design is beyond reproach, however at this moment it's uncertain what caused the battery pack to ignite. While it may have been a faulty battery, we don't know if the cell spacing exacerbated the problem or if the charge/discharge algorithms were faulty or if it was an as yet unknown factor.

What is clear is that Boeing pretty much went all in on 'Electric plane' concept and this made the Lithium battery a commitment rather than a contribution.

I'm still slightly surprised that there were no indications of potential battery problems during the testing/flight testing regime, these normally take each system to the edge of the envelope, yet no issues reported?
Hang on a minute shouldn't the design be "Fail Safe"? I wouldn't fancy flying 8 hours with a fire in the cabin. Just redesign the battery.
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Old 28th Feb 2013, 17:14   #1067 (permalink)
 
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I'm still slightly surprised that there were no indications of potential battery problems during the testing/flight testing regime, these normally take each system to the edge of the envelope, yet no issues reported?
Business & Technology | Electrical fire forces emergency landing of 787 test plane | Seattle Times Newspaper You been asleep for a few months? How on Earth did it get certified when a test A/C burst into flames?
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Old 28th Feb 2013, 17:29   #1068 (permalink)
 
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Have there been many (any?) total electrical power failures that haven't been caused by loss of the engines too? I can't think of any.
Qantas B744 Total electrical failure? [Archive] - PPRuNe Forums

The 747-400s APU cannot be started inflight, apparently as failure of all 4 gens was thought impossible.
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Old 28th Feb 2013, 19:40   #1069 (permalink)
 
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Business & Technology | Electrical fire forces emergency landing of 787 test plane | Seattle Times Newspaper You been asleep for a few months? How on Earth did it get certified when a test A/C burst into flames?
Was the actual cause of that fire during test ever released? Was it perhaps a battery incident???
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Old 28th Feb 2013, 20:32   #1070 (permalink)
 
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Ex Cargo Clown, inetdog

As it was a test flight, the incident has not been logged by the NTSB : List by Month
Therefore, no "official" report has been established by an independent body.
"Common" knowledge is that some FOD made its way in the aft electric panel and the whole thing burned down !
Flightblogger published a quite comprehensive summary of that incident No split over similar-looking wingtips - FlightBlogger - Aviation News, Commentary and Analysis
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Old 28th Feb 2013, 21:24   #1071 (permalink)
 
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Do you have any references for that, toffeez.
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Old 28th Feb 2013, 21:37   #1072 (permalink)
 
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glad rag

Just type "like Radio Shack" in the Seattle Times search engine and you'll get the source
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Old 28th Feb 2013, 21:45   #1073 (permalink)
 
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Thank you.
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Old 28th Feb 2013, 22:27   #1074 (permalink)
 
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OT

@llagonne66
Thank you, the Flight blogger link you provided, links to an interesting article The Seattle Times: Making It Fly on the 757 cert effort, dated 20 days before I flew out to HK.

It seems one had more time then to write up things like that, as well as to check things out thoroughly, in proportion to the complexity, that is.

Last edited by saptzae; 28th Feb 2013 at 22:38. Reason: Link
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Old 1st Mar 2013, 00:11   #1075 (permalink)
 
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It's happened before!

Mention of the 757 makes it opportune to note Boeing's difficulties with the introduction of aramid (KEVLAR) reinforced plastics on the 757/767. Aramid composites were chosen (in preference to carbon) on lightly loaded structure like trailing edge panels. Worked fine during certification but in real life temperature cycles caused aramid components to crack and absorb moisture within 4000 flight hours. All had to be sealed then replaced. A hugely expensive mistake. Service Bulletin 767-51-0008, April 1985 refers.
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Old 1st Mar 2013, 00:54   #1076 (permalink)
 
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Momoe;

Quote:
I'm still slightly surprised that there were no indications of potential battery problems during the testing/flight testing regime, these normally take each system to the edge of the envelope, yet no issues reported?
Not so close to the edge during flight tests. Subsystems are usually pushed much harder during bench (lab) testing. And therein lies a possible problem. With much of the testing being done by the subsystem vendors, the interactions between different subsystems may not have been tested adequately.

Its more likely* that Thales loaded the battery system down with a resistive load bank to simulate an APU start rather than actually obtaining production DC-AC converters and an APU starter/generator.

*Disclaimer: I wasn't there. But this has been my experience with past subsystem tests.
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Old 1st Mar 2013, 00:56   #1077 (permalink)
 
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An email doing the rounds at the moment
Quote:
For one thing the problem may not be with the batteries themselves, but with the control system that keeps the charge on them at a given level. And the 'battery problem" is just one problem in many. Last week I had my regular monthly lunch with 5 fellow Boeing engineers (all but one retired) and we talked at length about what we call the "nightmare liner". We all agreed we will not book a flight on one. The one engineer still working (at age 74!!) says the news from inside is not good, and that there are no quick fixes for the multitude of problems that the 787 has.

The disaster began with the merger with McDonnell-Douglas in the mid-90s. The McD people completely took over the Board and installed their own people. They had no experience with commercial airplanes, having done only "cost-plus" military contracting, and there are worlds of difference between military and commercial airplane design. Alan Mulally, a life-long Boeing guy, was against outsourcing as President of Boeing Commercial Division, but instead of making him CEO after he almost single-handedly saved the company in the early 90s, the Board brought in Harry Stonecipher from McDonnell-Douglas, who was big on outsourcing. Stonecipher was later fired for ethics violations, and then the Board brought in Jim McNerney, a glorified scotch tape salesman from 3M and big proponent of outsourcing, to develop the 787. (Alan Mulally left to become CEO of Ford and completely rejuvenated that company.) A McNerney and his bean-counting MBAs thought that instead of developing the 787* in-house* for about $11 billion, they could outsource the design and building of the airplane for about $6 billion. Right now they are at $23 billion and counting, three years behind in deliveries, with a grounded fleet. That's typical for military contracting, so McNerney and the Board probably think they are doing just fine. But it will destroy Boeing's commercial business in the same way McDonnell wrecked Douglas when they took over that company decades ago. Boeing had a wonderfully experienced team of designers and builders who had successfully created the 707, 727, 737, 747, 757, 767, and 777 in-house, always on-time, and mostly within budget, and with few problems at introduction. That team is gone, either retired or employed elsewhere. (I took early retirement after the McD takeover of Boeing because I knew the new upper management team was clueless.) The 787 was designed in Russia, India, Japan, and Italy. The majority of the airplane is built outside the US in parts and shipped to Seattle and Charleston for assembly. *Gee, what could possibly go wrong? * Answer: just about everything. Because the McD people that now run Boeing don't believe in R&D, the structure of the airplane will be tested *inservice*.

Commercial airplanes in their lifetime typically make ten times as many flights and fly ten times as many flight hours as military airplanes, so the argument that composite structure has been "tested" because of the experience of composite military airplanes is just so much BS. So structure is a big issue. The airplane is very overweight. The all-electric controls have the same lack-of-experience issue that the structure has. The only good news for me is that the Boeing pension plan is currently fully funded, although it may not stay that way as the 787 catastrophe develops.
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Old 1st Mar 2013, 05:13   #1078 (permalink)
 
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And the grounding continues.....

From the newswires....

Japan Airlines has further extended the suspension of its Boeing 787 operations to 31 May, three days after a similar announcement from its peer All Nippon Airways.
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Old 1st Mar 2013, 06:54   #1079 (permalink)
 
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Ex Cargo Clown

You been asleep for a few months?


Sharpen up mate! I was specifically referring to battery issues, the Laredo incident wasn't battery related or only indirectly in that if you short out the electrics by leaving an unsecured tool in the electrical bay you're asking for trouble.
Embarassing, yes. But it's nowt to do with the Lithium-Ion design issues.
Certification process is under scrutiny, but you can't expect any certifying agency to look at this incident and somehow extrapolate that the battery design is suspect.

Boeing accept that the current battery design isn't fail-safe, which is why they're proposing a fix. What most of the community on here are concerned about is the perceived nature of that fix, in that it's not appropriate for the job.

Last edited by Momoe; 1st Mar 2013 at 09:50.
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Old 2nd Mar 2013, 07:52   #1080 (permalink)
 
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Momoe

"you can't expect any certifying agency to look at this incident and somehow extrapolate that the battery design is suspect."


No, but there is a link which the FAA is aware of: the behaviour of the composite fuselage structure when exposed to extreme heat.

In the Laredo incident the fuselage insulating blankets caught fire, but the plane diverted quickly.

Boeing's battery "fix" allows the possibility of flying up to 3 hours with a very hot steel box under the floor. 1500 miles to the nearest firefighter.

Sure, the composite's fire resistance has been tested, but so were the batteries.
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