noistar
Final Assembly Line stage 2
Posts: 388
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Post by noistar on Jan 17, 2014 0:14:49 GMT 1
I do not think aircraft manufacturers deliberately accept unnecessary safety risks, but every decision is a trade-off. No aircraft is 100 % safe, even on the ground ! Your immediate concern seems to be the 787, but I do not think any of its designers ever thought the aircraft might be exposed to fire risks as a consequence of battery-related problems, they just happened to overlook the need for some essential steps ... The fix certainly was more costly than any design change at an early stage. My reference to and concern about the B787 is obviously driven by the high-profile nature of the problem. It has merely become a trigger for 'tip of the iceberg' thoughts. There are Air Mail restrictions on Lithium batteries as I found when trying to get camera batteries I can't source in Thailand, sent from the UK. The potential for issues with similar batteries being used continually in a flight-environment could surely have been anticipated, at least to a degree. A comparison might be: How less economic is the 'fix'? How less economic is the proven technology? Is it a fact that a major manufacturer has chosen to and been allowed to, continue production of a flawed design? I seem to recall fire-related incidents during the B787 flight tests - mind you, I also seem to recall Boeing pointing the finger at a non-US (British?) supplier of the guilty components. Not Boeing's fault !! Anyway, the battery issue is on the radar. My main concern remains things which are not on the radar. I believe we are now at a fundamental review stage. The A350 has the benefit of time. The B787 does not have that luxury. Will manufacturers therefore use the B787 and A350 as a checkpoint, before taking potentially dangerous decisions with the B797 and A360? Will organizations tasked with ensuring safety, now start to become more pro-active and demanding when being requested to certify the airworthiness of a design? I was informed in this forum that such organizations cannot be expected to understand the complexities of modern aircraft design. Perhaps they ought to. Presumably someone ticked the Lithium Batteries check box. In hindsight the B787 situation could have been anticipated - at least in my opinion. The facts were there I believe. How much could be achieved by employing lighter cabin crew - not as flippant as it sounds. The crew employed by EVA and Thai are significantly 'less bulky' than those I have witnessed on BA and Virgin  |
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philidor
in service - 6 years
Posts: 8,950
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Post by philidor on Jan 17, 2014 10:39:09 GMT 1
The crew employed by EVA and Thai are significantly 'less bulky' than those I have witnessed on BA and Virgin The same difference also characterised women I met in quite different circumstances ...  |
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Post by fanairbus on Jan 17, 2014 17:48:27 GMT 1
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noistar
Final Assembly Line stage 2
Posts: 388
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Post by noistar on Jan 17, 2014 23:40:29 GMT 1
I was under the impression the batteries for the B787 WERE needed. The Norwegian spokesman seems to be under a misapprehension that B787 batteries are a backup. I seem to recall an Airbus comment that in-flight the engines produce more than enough electrical power for 'nothing', whereas in the B787, Boeing took this onerous task off the engines and gave it to the bank of new, light batteries. I wait to be corrected, but this was my understanding. |
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philidor
in service - 6 years
Posts: 8,950
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Post by philidor on Jan 18, 2014 2:50:38 GMT 1
No, sorry to correct you, the fact that the 787 uses much more electric power than other aircraft does not mean that this power is supplied by its batteries !
The 787 enjoys several redundant power generation systems. The batteries are far from the most important of them, and they are therefore not the intended substitute for bleed air. They are mainly used to start the APU (the first step before starting the engines, unless airport services are used). Their new and specific task on the 787 is to power the brakes. This is by no means trivial, but I think they are only used as a back-up - I am not sure).
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noistar
Final Assembly Line stage 2
Posts: 388
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Post by noistar on Jan 21, 2014 12:20:33 GMT 1
No, sorry to correct you, the fact that the 787 uses much more electric power than other aircraft does not mean that this power is supplied by its batteries ! The 787 enjoys several redundant power generation systems. The batteries are far from the most important of them, and they are therefore not the intended substitute for bleed air. They are mainly used to start the APU (the first step before starting the engines, unless airport services are used). Their new and specific task on the 787 is to power the brakes. This is by no means trivial, but I think they are only used as a back-up - I am not sure). Thanks for the correction, which brief homwework (May-I-Google-That-For-You) confirms 787updates.newairplane.com/787-Electrical-Systems/787-Electrical-Systeminterested in the line "... Boeing goes further, assuming failure will occur and designing for the proper protections. Boeing also designs so that no single failure will cause an accident" not sure how you can accept a plane catching fire in-flight as NOT an SPF  |
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philidor
in service - 6 years
Posts: 8,950
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Post by philidor on Jan 21, 2014 13:12:40 GMT 1
interested in the line "... Boeing goes further, assuming failure will occur and designing for the proper protections. Boeing also designs so that no single failure will cause an accident" not sure how you can accept a plane catching fire in-flight as NOT an SPF You are right, their initial 787 battery design was not to their self-proclaimed standard, or to FAA's regulations, and that is why they got grounded and had to improve that design. Basically, the initial design failed both in terms of battery failure rate (which happened to be much higher than predicted by Boeing), and in terms of containment of any fallout from these failures (gases and liquids vented from failed batteries were shown not to be properly contained). The new design intended to address both issues by making failures less likely (the battery charging program has been changed to decrease the load in each battery) and better containing the consequences (a stronger battery box was designed and a new venting system now allows gases and liquids to be vented overboard). So far, the changes seem to have worked properly. |
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noistar
Final Assembly Line stage 2
Posts: 388
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Post by noistar on Jan 21, 2014 18:08:50 GMT 1
interested in the line "... Boeing goes further, assuming failure will occur and designing for the proper protections. Boeing also designs so that no single failure will cause an accident" not sure how you can accept a plane catching fire in-flight as NOT an SPF You are right, their initial 787 battery design was not to their self-proclaimed standard, or to FAA's regulations, and that is why they got grounded and had to improve that design. Basically, the initial design failed both in terms of battery failure rate (which happened to be much higher than predicted by Boeing), and in terms of containment of any fallout from these failures (gases and liquids vented from failed batteries were shown not to be properly contained). The new design intended to address both issues by making failures less likely (the battery charging program has been changed to decrease the load in each battery) and better containing the consequences (a stronger battery box was designed and a new venting system now allows gases and liquids to be vented overboard). So far, the changes seem to have worked properly. Let's keep our fingers crossed. However, despite appearances to the contrary, my safety concerns do not start and end with the B787! Were the A380 wing-rib-bracket cracks due to the design requirements or manufacturing? (things like over-tightening or stressing bolts/rivets). Do they fall-in the 'push for efficiency' category which concerns me? I have a rather wordy post lurking on my ipad which I composed en-route from Thailand. However I need to wait before I can retrieve it. Watch This Space  |
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Post by FabienA380 on Jan 21, 2014 18:46:51 GMT 1
Were the A380 wing-rib-bracket cracks due to the design requirements or manufacturing? There had been LOOONG discussions about this in the old forum............ Fabien |
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noistar
Final Assembly Line stage 2
Posts: 388
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Post by noistar on Jan 21, 2014 19:27:59 GMT 1
Were the A380 wing-rib-bracket cracks due to the design requirements or manufacturing? There had been LOOONG discussions about this in the old forum............ Fabien willco !!! |
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