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#21
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Is the 787 a failure ?
"Daryl" wrote in message
... It sounds like they are being overcharged. That is prevented by a simple card addition that prevents it on only of overcharging but undercharging. Easy fix. Daryl The Lithium medical and electric vehicle packs I worked on were controlled by ICs that monitored and recorded individual cell voltage and overall charge and discharge current. Those are point measurements that are easy to do. What's harder is detecting unexpected hot spots away from the temperature sensors. Minor differences (improvements) between the acceptance sample and production devices can change heat flow paths. http://www.mpoweruk.com/lithium_failures.htm |
#22
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Is the 787 a failure ?
Vaughn wrote:
On 1/25/2013 6:17 PM, Transition Zone wrote: The last time a plane was grounded was what? 1979? That's a big deal. I remember the A320 had an early scuff-up when it started out, The A300 was certainly a candidate for grounding after one lost a vertical stabilizer in 2001 for no apparent reason. Vital parts failing, falling off, and causing a plane crash with 100% fatalities sounds a whole lot more difficult to fix that the 787's electrical problem. The fact that the NTSB enquiry showed that the fust officer had overstressed the stabilizer by aggressive alternate full rudder inputs at a relatively high airspeed was a pretty good candidate for an 'apparent reason' as was the fact that the A300 had flown into the wake turbulence of a JAL 747-400 Bottom line is that the pilot overstressed the airframe as his use of alternate full rudder inputs resulted in large angle of sideslip which tore off the stabilizer. The loads imposed by the sideslip were more than double the design limits. The FAA airframe engineer stated that for any aircraft " a maneuver with alternating rudder inputs was an extreme maneuver and that, if the maneuver were performed, loads would build that would exceed the current requirements. He further stated that, if two sets of alternating rudder inputs were performed, a series of dynamic maneuvers would start that could lead the airplane into a severe dynamic situation where, at the proper frequency, this continued application of this surface would allow the motion of the airplane to build up to the point where the sideslip would become excessive and overload the airplane " The flight data recorder and CVR showed exactly such a sequence of rudder inputs was made. Keith |
#23
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Is the 787 a failure ?
On 1/26/2013 6:00 AM, Jim Wilkins wrote:
"Daryl" wrote in message ... It sounds like they are being overcharged. That is prevented by a simple card addition that prevents it on only of overcharging but undercharging. Easy fix. Daryl The Lithium medical and electric vehicle packs I worked on were controlled by ICs that monitored and recorded individual cell voltage and overall charge and discharge current. Those are point measurements that are easy to do. What's harder is detecting unexpected hot spots away from the temperature sensors. Minor differences (improvements) between the acceptance sample and production devices can change heat flow paths. http://www.mpoweruk.com/lithium_failures.htm I can see a problem that is being addressed in Electric Vehicles. Heat and cold. On an electric vehicle, getting the battery too cold will (not can) result in a degrading of the performance of the cells. The fix is adding an "Electric Blanket" to keep the battery warm (not hot). The residual power required by the blanket is negligible. You get back much more than you lose. Heat. I can see problems with the Lipo batteries. The battery they chose is one that is not on the list of Vehicle safe batteries. It is the best, the highest output but with it comes problems. Lithium cobalt oxide (LCO), for vehicles, is listed as unstable compared to the rest. It's very suspeptable to heat. And sitting on the ground running up on a hot day, the battery compartment will sky rocket in heat. The safest to use is the lead acid but it's very short lived in this application. To use any Lipo battery, it requires a cooling and a heating system to keep the battery at an optimal temperature. The LCO is just the worst of the lot for overrunning (catching fire, generating Oxygen when it burns) than any other Lipo battery. The Fix? Get rid of the LCO and temperature control the battery compartment. Even a Lead Acid doesn't like excessive cold or heat. But it won't turn into a major oxygen fire. Sometimes, newer isn't better. But the various other Lipo batteries are safer than the LCO which has a proven track record of burning. BTW, the LCO isn't the cheapest by far. The LipoMG battery is the cheapest but it has a low service charge rate. The Lipo4 has a decent service rate and is what is primarily used in various vehicle applications. But, maybe, the old Lead Acids may be the way to go on this one. They are the most stable and the most safe if you keep them in a wide range of temperatures. Newer isn't always better. Daryl -- http://tvmoviesforfree.com for free movies and Nostalgic TV. Tons of Military shows and programs. |
#24
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Is the 787 a failure ?
On 1/26/2013 8:18 AM, Keith W wrote:
Bottom line is that the pilot overstressed the airframe as his use of alternate full rudder inputs resulted in large angle of sideslip which tore off the stabilizer. The loads imposed by the sideslip were more than double the design limits. None of which excuses the design. Pilots are taught from day one that full deflection of flight controls is generally permissible below a certain magic "maneuvering speed" without causing harm to the airframe. Given that the accident flight was in the climb phase, that plane was almost certainly below that speed. So this turned out to be a flight limitation that the pilots hadn't been told about and was nowhere in the flight manual. This DESIGN DEFECT was "fixed" by changing the flight manual to add new flight limitations and retraining pilots. To be fair, I know of no other similar accidents since then. Going back to my central point, the A300 easily survived that negative publicity, as will the 787. |
#25
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Is the 787 a failure ?
Vaughn wrote:
On 1/26/2013 8:18 AM, Keith W wrote: Bottom line is that the pilot overstressed the airframe as his use of alternate full rudder inputs resulted in large angle of sideslip which tore off the stabilizer. The loads imposed by the sideslip were more than double the design limits. None of which excuses the design. Pilots are taught from day one that full deflection of flight controls is generally permissible below a certain magic "maneuvering speed" without causing harm to the airframe. Given that the accident flight was in the climb phase, that plane was almost certainly below that speed. Trouble it was at that speed which at the altitude in question was 250 knots. When the stabilizer failed the speed was at 251 knots and the pilot had applied full power So this turned out to be a flight limitation that the pilots hadn't been told about and was nowhere in the flight manual. True to an extent but the issue was not in an Airbus flight manual but in an FAA document ( Title 14 CFR 25.1583, "Operating Limitations") This stated that Quote that full application of rudder and aileron controls, as well as maneuvers that involve angles of attack near the stall, should be confined to speeds below this value." Quote This was found to be ambiguous in that it implied that multiple full deflection inputs were safe at or below the safety speed. This the NTSB and FAA found was not true for most large transport aircraft and the FAA document was amended to inform operators that operating at or below maneuvering speed does NOT provide structural protection against multiple full control inputs in one axis or full control inputs in more than one axis at the same time After the accident Boeing issued the following clarification to its users. "Boeing aircraft are not designed to a requirement of full authority rudder reversals from an "over yaw" condition. Sequential full or nearly full authority rudder reversals may not be within the structural design limits of the aircraft, even if the airspeed is below the design manoeuvring speed. " The AA flight training centre was using faulty simulator training that encouraged the use multiple cyclic full rudder inputs to control wake roll problems and had fostered the mistaken belief that the rudder limiter would prevent any bad results from excessive inputs. The extent of the forces caused by the rudder inputs may be gauged from the fact that the flight data recorder showed they caused alternate lateral accelerations of between 0.3 and 0.4 G This DESIGN DEFECT was "fixed" by changing the flight manual to add new flight limitations and retraining pilots. To be fair, I know of no other similar accidents since then. Going back to my central point, the A300 easily survived that negative publicity, as will the 787. I am sure that it will, battery and charging system problems should be easy to resolve. Keith |
#26
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Is the 787 a failure ?
"Mr.B1ack" wrote: On Fri, 25 Jan 2013 22:21:55 -0600, F. George McDuffee wrote: When you want it really really bad, that's generally how you get it... ----------------------- On Fri, 25 Jan 2013 20:54:55 -0600, "Mr.B1ack" wrote: snip Now from a business point of view however ... snip These URLs may be of interest. If an emergency is defined as an event that was unanticipated in occupance and limited in duration, clearly this is no emergency. That's TECHNICAL ... "legal" ... has NOTHING to do with how potential passengers should act or react. Passengers are convinced the 787 is a death-trap. That's ALL it takes to destroy it. All planes are death traps. You can't pull over to a cloud & call for a tow, for any of them. |
#27
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Is the 787 a failure ?
On Jan 25, 9:00*pm, Too_Many_Tools wrote:
On Jan 10, 2:02*pm, Transition Zone wrote: Date: Thu, 23 Dec 2010 21:23:55 -0500 Local: Thurs, Dec 23 2010 9:23 pm JF Mezei wrote: On December 23rd, Boeing announced it is now resuming flight testing on ZA004. They have updated the power distrubution *software* and will test this, along with deployment of RAT before resuming normal testing for certification. So it appears that the hammer that was left in some electrical cabinet probably highlighted some software problems. Thankfully, updating software is less tedious than having to dismantly, change a part and reassemble the number of 787s already built. A Week Boeing Would Like To Forget By Alex Zolbert, CNN, updated 2:01 PM EST, Thu January 10, 2013 More concerns for Dreamliner - (CNN) -- Some passengers pay no attention to what type of airplane they'll be flying on. Others are obsessed. I'd put myself in the middle of the pack, mainly due to the new planes on offer from Airbus and Boeing. So I was in slightly better spirits this week, as I boarded the 11- hour United Airlines flight from Los Angeles to Tokyo this week. It was my first chance to fly on a Boeing 787 Dreamliner. But the trip quickly descended into -- certainly not a nightmare -- but definitely a headache. Dreamliner catches fire at airport It's a drill millions of travelers know all too well. After starting the taxi out to the runway Monday morning, we were informed that there was an issue with the computer system, and they were unable to start one of the plane's engines. We remained onboard for nearly 3 hours, as flight attendants sheepishly offered cups of water to frustrated passengers. Eventually we disembarked. A delay of four hours turned into five, then six, seven ... and the flight was eventually canceled. We then had the pleasure of spending the night at an airport hotel that seemed to have been last updated around the time commercial air travel started. It was then that I realized we weren't the only ones encountering issues with the Dreamliner on Monday. A Japan Airlines' 787 caught fire in Boston after passengers disembarked. Boeing said the fire was traced to a battery unit that helps to power electrical systems when the engines are idle -- typically while a plane is being serviced or cleaned. And the company says it's cooperating with investigators. As Tuesday morning arrived, we were back on board another United Airlines' Dreamliner in Los Angeles. But in a rather comical turn of events, the second plane never left the gate. We were told there was an issue with the paperwork filed with the FAA. More than a day late, many coffees, and very little sleep later, the third time finally proved to be the charm -- more than 24 hours after our scheduled departure. But as we finally took to the skies, more Dreamliner issues were unfolding. Another Japan Airlines' 787 in Boston had to scrap a takeoff on Tuesday due to a fuel leak. And an ANA Dreamliner flight was canceled in Japan on Wednesday, because of a glitch with its brake system. But Boeing is standing by its latest aircraft. The company's chief project engineer, Mike Sinnett, says he is "100% convinced the airplane is safe to fly." Analysts seem not to be alarmed, saying that new aircraft models often have "growing pains." But what is very clear is this was a week that Boeing would certainly like to forget. After a nearly 40-hour trip back home, I'll second that. --http://www.cnn.com/2013/01/10/business/dreamliner-los-angeles/ BIG problem. The batteries are obviously being overcharged..a system problem. To fix the problem and have the recertifications will take time..and BIG dollars until the plane files again. I suspect it is a failure to properly oversee system integration within Boeing. And where there is smoke there is fire...if the electrical system has not been properly reviewed it is a KEY signal that there are other similar oversights. Bottom line..if I were actively flying I would NOT fly the 787 for years...let someone else be the lab rat. Other planes have made bad splashes into the market or service and later fared better. Here, I think the battery system was being strained; i.e. being used without a diesel (jet fuel) powered main power unit, which all planes on the ground need. Probably human error. |
#28
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Is the 787 a failure ?
On Jan 25, 9:54*pm, "Mr.B1ack" wrote:
Strictly speaking, the 787 is not an engineering failure. Like anything complex and new it has a few issues. So far these issues haven't caused any fatalities. But, the then-new EU Airbus airliner (A320) did have mostly fatalities on an opening day mess-up, back on June 26, 1988, at Mulhouse-Habsheim Airport. Airbus's A380 had terrible delays, too. In a year or two, offer a "797" ... Beoing's 787 didn't have any fatalities. So, I'd say stick with the current program. (especially, if Airbus weathered and overcame their mistakes) |
#29
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Is the 787 a failure ?
On Jan 26, 11:28*am, "Michael A. Terrell"
wrote: "Mr.B1ack" wrote: On Fri, 25 Jan 2013 22:21:55 -0600, F. George McDuffee wrote: When you want it really really bad, that's generally how you get it.... ----------------------- On Fri, 25 Jan 2013 20:54:55 -0600, "Mr.B1ack" wrote: snip Now from a business point of view however ... snip These URLs may be of interest. *If an emergency is defined as an event that was unanticipated in occupance and limited in duration, clearly this is no emergency. * *That's TECHNICAL ... "legal" ... has NOTHING to do * *with how potential passengers should act or react. * *Passengers are convinced the 787 is a death-trap. * *That's ALL it takes to destroy it. * *All planes are death traps. No, this isn't the 1930's anymore. You can't pull over to a cloud & call for a tow, for any of them. Since then, you hardly ever have crashes because of all-weather designs, flight patterns and glide paths (in case you need to land). |
#30
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Is the 787 a failure ?
On Sat, 26 Jan 2013 01:42:01 -0600, "Mr.B1ack"
wrote: On Fri, 25 Jan 2013 22:21:55 -0600, F. George McDuffee wrote: When you want it really really bad, that's generally how you get it... ----------------------- On Fri, 25 Jan 2013 20:54:55 -0600, "Mr.B1ack" wrote: snip Now from a business point of view however ... snip These URLs may be of interest. If an emergency is defined as an event that was unanticipated in occupance and limited in duration, clearly this is no emergency. That's TECHNICAL ... "legal" ... has NOTHING to do with how potential passengers should act or react. Passengers are convinced the 787 is a death-trap. That's ALL it takes to destroy it. You are convinced passengers are convinced. There have been no deaths, no injuries, and only limitted damage to this point. A minor tweek will likely solve the battery problem. It appears to be a problem with the APU not knowing how to handle Lithium batteries, as the problem occurs when on the ground with the APU running the system. |
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