ANA fire extinguisher wiring faults
Is it a single, remote double headed bottle then plumbs to either engine? Or does each engine have it's own bottle? is that bottle double headed to it's own engine for redundancy? [my bet
Last edited by tdracer; 17th Aug 2013 at 19:20.
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Actually you stated
so I took that your input was, as mine, supposition.
I don't work the 787, and I don't have any 'inside' info - what I know about this incident is what I've read in the news.
tdracer:
And this is a problem with systems such as these. Because the fire bottles are 'one shot' systems, one cannot do a complete end-to-end functional test of them. The aircraft wiring can be tested, usually with a test tool that breaks out the squib signals. But that requires additional steps in the manufacturing process: hook up the tool, run the test, remove the tool, etc. After that, the bottles must be connected. And that must be done without introducing errors.
There are system designs that can eliminate crossed connections and other such mistakes. Keyed electrical connectors and/or wiring harnesses that won't allow the left connector to reach the right squib, for example, can be employed. But a lot of these require an attention on the part of engineering to not only eliminate system failures in operation, but to account for possible manufacturing errors in their designs. And to cover most error cases with the proper combination of designing them out and functional test/maintenance procedures to eliminate others.
Unfortunately, the trend in aircraft design and manufacturing is to separate engineering from manufacturing, both within organizations and across different companies. What used to be a matter of engineering paying visits to the shop floor and getting feedback from the people actually putting things together now consists of official inter-company correspondence, design change paperwork and lots of extra charges.
The functional test at the aircraft level insures the aircraft wiring is correct. The fire bottle is an LRU - functional tests don't normally check the LRU. The vendor is supposed to verify the LRU wiring is correct.
There are system designs that can eliminate crossed connections and other such mistakes. Keyed electrical connectors and/or wiring harnesses that won't allow the left connector to reach the right squib, for example, can be employed. But a lot of these require an attention on the part of engineering to not only eliminate system failures in operation, but to account for possible manufacturing errors in their designs. And to cover most error cases with the proper combination of designing them out and functional test/maintenance procedures to eliminate others.
Unfortunately, the trend in aircraft design and manufacturing is to separate engineering from manufacturing, both within organizations and across different companies. What used to be a matter of engineering paying visits to the shop floor and getting feedback from the people actually putting things together now consists of official inter-company correspondence, design change paperwork and lots of extra charges.
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about wiring error
Interesting- RE the many news headlines based on supposition re wiring error, the eventual FACTS reveal a wrong ASSEMBLY error by the vendor.
Granted the 787 has had many electrical problems and some actual wiring errors or if not errors simple " what were they thinking " kinds of errors.
And of course the issue immdiately brought up the pundits re battery fiasco issue and the ELT issue- none of which are related to the fire bottle problem
Thus the legacy of the 787 will forever be " wiring " . . .
Which will be repeated for any problem- CFIT, runway overruns, solid clouds, etc.
Its like a lawyer friend once told us in class- when you read in the news about a case or a court opinion, you can be assured it is only partially correct as reported. IF you really want the details and facts - read the court documents.
Granted the 787 has had many electrical problems and some actual wiring errors or if not errors simple " what were they thinking " kinds of errors.
And of course the issue immdiately brought up the pundits re battery fiasco issue and the ELT issue- none of which are related to the fire bottle problem
Thus the legacy of the 787 will forever be " wiring " . . .
Which will be repeated for any problem- CFIT, runway overruns, solid clouds, etc.
Its like a lawyer friend once told us in class- when you read in the news about a case or a court opinion, you can be assured it is only partially correct as reported. IF you really want the details and facts - read the court documents.
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EEngr
So you expect the operator to carry out periodic operational or function checks on the system, but not Boeing during system testing prior to delivery?
No wonder then, British Airways third B787, B1 flight lasted less than 20 minutes.
No wonder then, British Airways third B787, B1 flight lasted less than 20 minutes.
So you expect the operator to carry out periodic operational or function checks on the system, but not Boeing during system testing prior to delivery?
The problem is that this is one of those functions that cannot be easily tested from end to end. because that would involve discharging the bottles. So some attention must be paid at the design stage to possible errors that could be introduced during the manufacturing or maintenance steps to ensure that the possibility of such errors are minimized. Basically, make things so there's only one way they can go together correctly. And this includes the suppliers of various components, like the fire bottles.
BTW, if some of you are wondering if Boeing selected some fly-by-night vendor to save a few buck, press reports indicate the vendor was Kiddie - probably the largest manufacturer of commercial aircraft fire detection and fire extinguishing systems.
I expect there will be an investigation of Kiddie to understand how they could have botched this bad. Depending on the results of that investigation, I won't be surprised if inspections extend beyond the 787 (as I also noted in my first post).
I expect there will be an investigation of Kiddie to understand how they could have botched this bad. Depending on the results of that investigation, I won't be surprised if inspections extend beyond the 787 (as I also noted in my first post).
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EEngr & tdracer
I am no avionics engineer but l know you can remove the plug and check that when you test the system, the signal you are sending to the R/H head does actually arrive at that head and not the other head.
With regards to Kiddie, Boeing normally has a choice for Fire Bottles on other types, but l believe the B787 has only Kiddie fitted, nine of them if my memory serves me.
So it will not only be other aircraft types being checked.
With regards to Kiddie, Boeing normally has a choice for Fire Bottles on other types, but l believe the B787 has only Kiddie fitted, nine of them if my memory serves me.
So it will not only be other aircraft types being checked.
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the vendor was Kiddie - probably the largest manufacturer of commercial aircraft fire detection and fire extinguishing systems.
As it's predominantly plastic and metal, I assume that it's a geographic ,as opposed to constituant reference
For at least 45 years, automotive and industrial wiring has routinely used non-interchangeable multiplugs A very basic safety-control on an unskilled or low-intelligence assembly-line. To improve speed even more, M-F connectors are often moulded in a unique colour,thus making it obvious if a forced mis-mate is attempted.
One has to question the sort of quality-control that allowed delivery of very expensive "rejects".
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MURPHY STRIKES AGAIN.
Sounds like another major aircraft tech problem which could have been arrested and stopped at the drawing board stage?
Eengr and others have nailed it with the speculation re the real engineers being fired and whizz-kids being employed who know the square root of
all about aeroplanes and how they work.
Ever since crossed control connections killed pilots, it was a rule that NO system should be able to be misconnected.
Yet the RAF managed to lose a Hawk pilot due to such a misdesign where the controls were crossed post maintenance and now here we are in the 21st century with mega-buck civil transport aircraft suffering similar glitches.
When will THEY ever learn??!!
Eengr and others have nailed it with the speculation re the real engineers being fired and whizz-kids being employed who know the square root of
all about aeroplanes and how they work.Ever since crossed control connections killed pilots, it was a rule that NO system should be able to be misconnected.
Yet the RAF managed to lose a Hawk pilot due to such a misdesign where the controls were crossed post maintenance and now here we are in the 21st century with mega-buck civil transport aircraft suffering similar glitches.
When will THEY ever learn??!!
Mr @ Spotty M
That's my recollection of the system as well. A simple test light can verify the cockpit to fire bottle wiring integrity. If Boeing can be bothered to spare two technicians and a couple of handheld radios. Likewise, proper routing of flexible Halon tubing can be verified with compressed air or dry nitrogen prior to installing squibs or burst discs. But that's a manufacturing step and the bean counters love eliminating those.
It might be the case that using keyed connectors is not possible due to the same model number fire bottle being used on too many different aircraft to retrofit a design change. However, I seem to recall that the layout of the electrical and halon plumbing on a fire bottle is such that the 'Left' plug is physically adjacent to the 'Left' Halon outlet. So fastening the plumbing and wiring in a simple clamp would prevent accidentally separating one system's connections.
A diagram of the bottles and 787 installation would help greatly.
I am no avionics engineer but l know you can remove the plug and check that when you test the system, the signal you are sending to the R/H head does actually arrive at that head and not the other head.
It might be the case that using keyed connectors is not possible due to the same model number fire bottle being used on too many different aircraft to retrofit a design change. However, I seem to recall that the layout of the electrical and halon plumbing on a fire bottle is such that the 'Left' plug is physically adjacent to the 'Left' Halon outlet. So fastening the plumbing and wiring in a simple clamp would prevent accidentally separating one system's connections.
A diagram of the bottles and 787 installation would help greatly.
DWS
Having been on the inside at Boeing, the legacy of practically every screw-up there seems to be "wiring". Wiring is one of the biggest configuration control problems in the manufacturing of any aircraft. It touches every other system, so any changes within one subsystem also affects the wiring.
The configuration control systems needed to track changes in the wiring systems are orders of magnitude more complex than any other aircraft subsystem. Add to that the large number of engineering, manufacturing, QA and vendor groups involved, each with their own organizational empires and fixing anything becomes a nightmare. Everyone seems to have their own work-arounds to plug holes in the official processes. Enforcing one way of doing business is a problem (Airbus has their own issues getting bundles to fit a few years back if I recall correctly).
Thus the legacy of the 787 will forever be " wiring " . . .
The configuration control systems needed to track changes in the wiring systems are orders of magnitude more complex than any other aircraft subsystem. Add to that the large number of engineering, manufacturing, QA and vendor groups involved, each with their own organizational empires and fixing anything becomes a nightmare. Everyone seems to have their own work-arounds to plug holes in the official processes. Enforcing one way of doing business is a problem (Airbus has their own issues getting bundles to fit a few years back if I recall correctly).
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The configuration control systems needed to track changes in the wiring systems are orders of magnitude more complex than any other aircraft subsystem.
I hope one of the 'lessons learned' from all this is the need for a system that can respond to the need to handle rapid change. To be blunt, the systems just didn't do that, so what then happens is folk everywhere are using their best efforts to 'do the right thing' to keep the program moving forward - because there are a bunch of MBAs beating you with their schedules, spreadsheets and the really evil 'P4S' * - so it degenerates into a bit of a mare's nest.
* P4S or 'Plan for Success' seemed to be a management idea that stripped out every bit of contingency from your plan and thus enabled you to deliver earlier.
So, for instance, you plan to prototype of a bit of new and critical electronics then test it but allow for time to re-spin the circuit board if it didn't work quite right or failed EMC tests or whatever, P4S ensured that allowance would be pulled out at review and the plan assumed it would be 'right first time' - well guess what!
Still, you can tell it worked because we came in dead on schedule didn't we.....
...oh we didn't? That will be those pesky engineers again then.
Last edited by fenland787; 19th Aug 2013 at 21:20.
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was once involved with a spoiler defect on an Airbus A300-600 - the spoilers are primary roll control and FBW - where some of the servo valves and the indication system were wired up wrongly. The aircraft had been in service for at least a year and the fault was not apparent until a valve showed a failure on the ECAM but a physical check showed that it was a different spoiler that had failed.
The wiring had been assembled incorrectly at manufacture - symmetrically so no handling control problem ensued.It was kept very quiet at the time!
The wiring had been assembled incorrectly at manufacture - symmetrically so no handling control problem ensued.It was kept very quiet at the time!
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This thread set a train of thought in motion and I recalled another occasion when cooling #7 brake unit on a B747 with an air conditioning unit the temp indication stayed the same but #8 temp indication fell.The temp probes were cross connected.
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I have been concerned about Management style and attitude throughout business and industry for a number of years.
Nowadays it seems normal for managers NOT to know about the business itself, just how to make rules and create bureaucracy. This seems particularly so in UK and a recent TV series highlighted the far better management style in Germany.
This does not just apply to aviation or any one company, but Fenland's post about MBAs and P4S is exactly what concerned me when I first learned that Boeing's management had completely separated themselves from the actual business of making planes.
Developing and introducing a new airliner is such a complex affair, and to think of a remote management imposing rules and deadlines on the work, despite being hundreds of miles away and having little "hands-on" knowledge of it, just seems to me to be the wrong way to undertake any complex industrial project.
Nowadays it seems normal for managers NOT to know about the business itself, just how to make rules and create bureaucracy. This seems particularly so in UK and a recent TV series highlighted the far better management style in Germany.
This does not just apply to aviation or any one company, but Fenland's post about MBAs and P4S is exactly what concerned me when I first learned that Boeing's management had completely separated themselves from the actual business of making planes.
Developing and introducing a new airliner is such a complex affair, and to think of a remote management imposing rules and deadlines on the work, despite being hundreds of miles away and having little "hands-on" knowledge of it, just seems to me to be the wrong way to undertake any complex industrial project.
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a recent TV series highlighted the far better management style in Germany
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I agree that the opinion of a TV programme maker can be quite wide of reality, and as stated I was not aiming my remarks solely at Boeing!
From a lifetime of observation and experience I have seen that much British business has been "managed" into extinction!
From a lifetime of observation and experience I have seen that much British business has been "managed" into extinction!