FAA Grounds 787s
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Turin,
thanks for the succinct clarification.
Getting back to the Laredo incident, IIRC, this had major electrical issues on approach and deployed the RAT to power basic instrumentation.
Did this affect the brakes? Even if they weren't working I'm assuming that the reverse thrust system was available?
thanks for the succinct clarification.
Getting back to the Laredo incident, IIRC, this had major electrical issues on approach and deployed the RAT to power basic instrumentation.
Did this affect the brakes? Even if they weren't working I'm assuming that the reverse thrust system was available?
As far as I know the battery powered emergency brakes worked as advertised.
T/reversers are hydraulic so unless there was a problem with the power to the control circuits (which are independent) they should have been fine.
T/reversers are hydraulic so unless there was a problem with the power to the control circuits (which are independent) they should have been fine.
If a combination of events cannot be shown to be extremely improbable (< 10^-9 per flight hour), then some backup system needs to be provided
I simply look at what is currently demonstrated over the last 20 years and judge according to that scale..
Usual disclaimers apply!
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Most of the batteries were removed for low charge state. ie the towing switch left on or extended tows using the lights and brakes.
A full charge of the batteries will give approx 1hr use of power to the ACP, exterior lights, flt deck dome light, and brakes. This drops significantly with a lower voltage state. (15mins at 29.7v)
IIRC One of the 'failed' batteries, the a/c had dispatched with a battery message (that was at the time a MEL item).
A full charge of the batteries will give approx 1hr use of power to the ACP, exterior lights, flt deck dome light, and brakes. This drops significantly with a lower voltage state. (15mins at 29.7v)
IIRC One of the 'failed' batteries, the a/c had dispatched with a battery message (that was at the time a MEL item).
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Brake electrical requirement
Mk 1:
From the public graphics of the brake system, a set of motor driven actuators compress and release a group of carbon disks. The worm gear drive appears to prevent movement except under power.
So if the brakes are applied to a certain pressure and corresponding braking torque, they will maintain that braking until the actuators are driven in the opposite direction.
The accompanying text says that the system gives "proportional control" of braking force.
If you wanted to, you could probably set the brakes before landing.
where is the energy that keeps the brakes applied? As the aircraft slows the RAT rotation slows ergo the power output decreases. Or are the brakes of the type that when engaged will 'lock' onto that position?
So if the brakes are applied to a certain pressure and corresponding braking torque, they will maintain that braking until the actuators are driven in the opposite direction.
The accompanying text says that the system gives "proportional control" of braking force.
If you wanted to, you could probably set the brakes before landing.
Last edited by inetdog; 7th Mar 2013 at 01:08.
lomapaseo;
A combination of failures that lead to the loss of the aircraft. But in general terms, it depends on what you are concerned with. The important thing is that the requirement is given in terms of events per flight hour. So the issue of ETOPS/non-ETOPS, flight duration or time to an alternate field doesn't enter into the calculation. If the system reliability doesn't meet requirements, no flights should be permitted.
Yes, I understand the problem people are having flying around with a battery on fire. Assuming that can be contained, and the aircraft can be flown safely, that still doesn't address the issue of the battery not providing its intended function. Fire or not.
I fear that Boeing is using some weasel words surrounding ETOPS just to get the airplanes back in the air for PR purposes.
It's not helpful to suggest a meaningless target rate (< 10^-9 per flight hour), unless you define what classifies as an "event".
Yes, I understand the problem people are having flying around with a battery on fire. Assuming that can be contained, and the aircraft can be flown safely, that still doesn't address the issue of the battery not providing its intended function. Fire or not.
I fear that Boeing is using some weasel words surrounding ETOPS just to get the airplanes back in the air for PR purposes.
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But, crucially, "due to the ongoing investigation no conclusions or recommendations will be offered at this time" (or words to the same effect).
Which makes me wonder whether the FAA will be comfortable signing off on Boeing's proposed "fix".
Which makes me wonder whether the FAA will be comfortable signing off on Boeing's proposed "fix".
Not too many surprises in the interim document but reading through the firemens' reports, I do wonder if we'd be dredging the ocean for the remains of a 787, had this occurred mid-flight. Must have used several hundred pounds of extinguishant and eventually had to hack the battery out of the aeroplane. 1hr 40mins to get it under control... 
One thing that seems to be developing is a split between the FAA and the NTSB, the Feds siding with Boeing, and the NTSB seeming to be coming to much more cautious views. I somehow get the impression that this also represents a split between the manufacturer and the purchasers/operators, along similar lines.
It really is surprising that Boeing still doesn't know the root cause, like why the battery shorted in the first place, and why the multiple safety systems then didn't work, which is what the NTSB seem to be gunning for, not so much the FAA. Has McNerney really outsourced everyone who might be expert in this ? De Havilland got to the root cause of the initially inexplicable Comet metal fatigue accidents when all the evidence was laying at the bottom of the Mediterranean. Boeing are fortunate that is not at all the case here.
It really is surprising that Boeing still doesn't know the root cause, like why the battery shorted in the first place, and why the multiple safety systems then didn't work, which is what the NTSB seem to be gunning for, not so much the FAA. Has McNerney really outsourced everyone who might be expert in this ? De Havilland got to the root cause of the initially inexplicable Comet metal fatigue accidents when all the evidence was laying at the bottom of the Mediterranean. Boeing are fortunate that is not at all the case here.
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After start, APU still needs battery to operate
Per the NTSB report, after the APU starts, the APU battery must continue to supply power to the APU control electronics. When the JAL battery failed, the APU shut down.
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I think that once the general public reads the fire fighters account...things will have a bit of a different flavor going forward..
Note that there are public hearings schedule for NEXT month...this appears far from over...
In reading the NTSB report, and the article below, this appears to paint a very different picture than we have heard before...
The fire fighters were not aware of Li nor were able to contain the fire...the peripheral damage is certainly cause for alarm, and as the battery for the avionics is a UPS, very much cause for alarm...
in flight..well damn..
From Seattle Times...
Boston airport firefighters encountered sizzling liquid and a hissing, “exploding” battery when they entered the 787 at the center of a two-month-long National Transportation Safety Board investigation, according to documents released Thursday.
The NTSB said Thursday it plans two public hearings next month, one to explore lithium-ion battery technology in general and another to discuss the design and certification of the Boeing 787 battery system.
The safety agency announced the hearings as it released an interim factual report and 499 pages of related documents on its investigation of the Japan Airlines 787 fire at the Boston airport on January 7.
Among the findings in the documents released Thursday:
• Boeing outsourced both the analysis and testing of the battery system’s safety, performed to get Federal Aviation Adminstration (FAA) certification, to its battery system subcontractor, Thales of France, and to the battery maker, GS Yuasa of Japan.
“Theses analyses and tests were performed by Thales/GS-Yuasa and reviewed by Boeing,” the NTSB states.
• The safety analysis by Thales and GS Yuasa determined that “overcharging was the only known failure mode” that could result in fire. Boeing therefore built safeguards into the system to “to ensure that the likelihood of occurrence of an overcharge event” was less than one in a billion — which is the usual FAA standard in providing for potentially catastrophic events.
However, there is no indication in the NTSB documents that the battery that caught fire was overcharged.
Investigators inspected a hefty electrical contactor — a relay switch — that is part of the battery management system and was designed to open the electrical points and disconnect the cells in the event of an overcharge.
The heavily blackened contactor was found to be “in the de-energized closed orientation,” meaning that no overcharge had registered with the system and the contactor had not disconnected the cells.
• The NTSB a month ago established that the fire instead started with an internal short circuit of a single cell in the eight-cell battery.
Boeing’s pre-certification testing did try to evaluate the effect of an internal short circuit. It chose to do so with a test that punctured a cell with a nail to induce a short circuit.
“This test resulted in venting with smoke but no fire,” the NTSB reported.
Boeing also consulted with other companies about their experience with the use of similar lithium battery cells and “based on this information, Boeing assessed that the likelihood of occurrence of cell venting would be about one in ten million flight hours.”
The 787 that caught fire in Boston had logged just 169 flight hours, the report states.
And the entire operational fleet of 787s had logged a total of 51,662 in-service hours, plus about 6,000 flight test hours.
• On the day of the Boston fire, the battery did not behave as Boeing or subcontractor Thales predicted.
The battery’s power discharge was “not at the constant rate described by the Boeing or Thales documents and included large changes and reversals of power within short periods of time,” according to the NTSB’s preliminary report.
• Sitting on a rack above the battery that burned was a smaller lithium ion battery, also supplied by Japanese manufacturer GS Yuasa, that is used to provide emergency power for the jet’s flight controls “for a minimum of 10 minutes when no other electrical power is available.”
Investigators found the exterior of this battery had been “lightly scorched” by the fire below and noted that its case had openings at the corners.
• No heat damage was found to any primary airplane structure.
However, the floor panel and carbon fiber floor support material, which are considered to be secondary structure, “were found to be heat damaged beneath where the APU battery had been installed.”
• The firefighters who were called to put out the fire did not know they were dealing with a lithium-ion battery, and had great difficulty putting out the intense fire.
When Capt. Mark Munroe of the airport’s aircraft rescue and firefighting (ARFF) unit entered the plane, he “saw heavy white smoke billowing through the floor” of the passenger cabin.
After locating the fire inside the electronics bay in the belly of the airplane, firefighters entered the compartment through dense smoke and applied shots of Halotron fire extinguisher to the battery.
Lt. David Hoadley of the ARFF unit reported that “It seemed like the fire did not want to go out, it kept rekindling.”
Then the battery “exploded,” according to Capt. Monroe.
“Capt. Munroe heard the battery hissing still and pushing white smoke or steam. There was liquid sizzling over the sides of the battery and still heavy smoke conditions. ... The battery continued to hiss before exploding.”
Monroe related that “he felt something hit him in the neck while he was in the airplane,” and he was sent out for medical treatment. “Something had burned his neck.”
Firefighters attempted to remove the battery from the jet, but found that the “quick disconnect” mechanism Boeing had included to allow mechanics to take out the battery for maintenance was “melted and un-recognizable” and a metal plate was preventing access.
The battery had to be cut out from the rack where it sat.
“With a hot battery and a gloved hand (Lt. Hoadley) could not access the bolts on the lower rails with tools. They attempted with pliers to remove the bolts for maybe 20 minutes. What looked like Teflon slides were burnt away and the battery would not move. There were 3 more screws that could not be removed.”
Firefighters cut away the metal plate, severed the battery wire, then “pried the battery loose with hydraulic spreaders and removed it.”
The battery was passed down to a firefighter and placed on the tarmac about 50 feet from the airplane.
The fire was declared under control an hour and forty minutes after the initial notification.
Boeing’s entire fleet of 787s has been grounded since a second battery incident during a flight in Japan, a week after the Boeing fire.
The company’s proposed fix for its battery system is currently under review by the FAA.
The agency expected to make an initial recommendation next week that will lay
NTSB: Boeing outsourced 787 battery safety analysis to subcontractors | Business & Technology | The Seattle Times
Note that there are public hearings schedule for NEXT month...this appears far from over...
In reading the NTSB report, and the article below, this appears to paint a very different picture than we have heard before...
The fire fighters were not aware of Li nor were able to contain the fire...the peripheral damage is certainly cause for alarm, and as the battery for the avionics is a UPS, very much cause for alarm...
in flight..well damn..
From Seattle Times...
Boston airport firefighters encountered sizzling liquid and a hissing, “exploding” battery when they entered the 787 at the center of a two-month-long National Transportation Safety Board investigation, according to documents released Thursday.
The NTSB said Thursday it plans two public hearings next month, one to explore lithium-ion battery technology in general and another to discuss the design and certification of the Boeing 787 battery system.
The safety agency announced the hearings as it released an interim factual report and 499 pages of related documents on its investigation of the Japan Airlines 787 fire at the Boston airport on January 7.
Among the findings in the documents released Thursday:
• Boeing outsourced both the analysis and testing of the battery system’s safety, performed to get Federal Aviation Adminstration (FAA) certification, to its battery system subcontractor, Thales of France, and to the battery maker, GS Yuasa of Japan.
“Theses analyses and tests were performed by Thales/GS-Yuasa and reviewed by Boeing,” the NTSB states.
• The safety analysis by Thales and GS Yuasa determined that “overcharging was the only known failure mode” that could result in fire. Boeing therefore built safeguards into the system to “to ensure that the likelihood of occurrence of an overcharge event” was less than one in a billion — which is the usual FAA standard in providing for potentially catastrophic events.
However, there is no indication in the NTSB documents that the battery that caught fire was overcharged.
Investigators inspected a hefty electrical contactor — a relay switch — that is part of the battery management system and was designed to open the electrical points and disconnect the cells in the event of an overcharge.
The heavily blackened contactor was found to be “in the de-energized closed orientation,” meaning that no overcharge had registered with the system and the contactor had not disconnected the cells.
• The NTSB a month ago established that the fire instead started with an internal short circuit of a single cell in the eight-cell battery.
Boeing’s pre-certification testing did try to evaluate the effect of an internal short circuit. It chose to do so with a test that punctured a cell with a nail to induce a short circuit.
“This test resulted in venting with smoke but no fire,” the NTSB reported.
Boeing also consulted with other companies about their experience with the use of similar lithium battery cells and “based on this information, Boeing assessed that the likelihood of occurrence of cell venting would be about one in ten million flight hours.”
The 787 that caught fire in Boston had logged just 169 flight hours, the report states.
And the entire operational fleet of 787s had logged a total of 51,662 in-service hours, plus about 6,000 flight test hours.
• On the day of the Boston fire, the battery did not behave as Boeing or subcontractor Thales predicted.
The battery’s power discharge was “not at the constant rate described by the Boeing or Thales documents and included large changes and reversals of power within short periods of time,” according to the NTSB’s preliminary report.
• Sitting on a rack above the battery that burned was a smaller lithium ion battery, also supplied by Japanese manufacturer GS Yuasa, that is used to provide emergency power for the jet’s flight controls “for a minimum of 10 minutes when no other electrical power is available.”
Investigators found the exterior of this battery had been “lightly scorched” by the fire below and noted that its case had openings at the corners.
• No heat damage was found to any primary airplane structure.
However, the floor panel and carbon fiber floor support material, which are considered to be secondary structure, “were found to be heat damaged beneath where the APU battery had been installed.”
• The firefighters who were called to put out the fire did not know they were dealing with a lithium-ion battery, and had great difficulty putting out the intense fire.
When Capt. Mark Munroe of the airport’s aircraft rescue and firefighting (ARFF) unit entered the plane, he “saw heavy white smoke billowing through the floor” of the passenger cabin.
After locating the fire inside the electronics bay in the belly of the airplane, firefighters entered the compartment through dense smoke and applied shots of Halotron fire extinguisher to the battery.
Lt. David Hoadley of the ARFF unit reported that “It seemed like the fire did not want to go out, it kept rekindling.”
Then the battery “exploded,” according to Capt. Monroe.
“Capt. Munroe heard the battery hissing still and pushing white smoke or steam. There was liquid sizzling over the sides of the battery and still heavy smoke conditions. ... The battery continued to hiss before exploding.”
Monroe related that “he felt something hit him in the neck while he was in the airplane,” and he was sent out for medical treatment. “Something had burned his neck.”
Firefighters attempted to remove the battery from the jet, but found that the “quick disconnect” mechanism Boeing had included to allow mechanics to take out the battery for maintenance was “melted and un-recognizable” and a metal plate was preventing access.
The battery had to be cut out from the rack where it sat.
“With a hot battery and a gloved hand (Lt. Hoadley) could not access the bolts on the lower rails with tools. They attempted with pliers to remove the bolts for maybe 20 minutes. What looked like Teflon slides were burnt away and the battery would not move. There were 3 more screws that could not be removed.”
Firefighters cut away the metal plate, severed the battery wire, then “pried the battery loose with hydraulic spreaders and removed it.”
The battery was passed down to a firefighter and placed on the tarmac about 50 feet from the airplane.
The fire was declared under control an hour and forty minutes after the initial notification.
Boeing’s entire fleet of 787s has been grounded since a second battery incident during a flight in Japan, a week after the Boeing fire.
The company’s proposed fix for its battery system is currently under review by the FAA.
The agency expected to make an initial recommendation next week that will lay
NTSB: Boeing outsourced 787 battery safety analysis to subcontractors | Business & Technology | The Seattle Times
Last edited by FlightPathOBN; 7th Mar 2013 at 20:07.
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toffeez,
I think that once the general public (ie Senators, Regulators, etc) reads the detailed account of the fire fighters, there will be a call for much higher scrutiny of the fix and certification moving forward. Technicalities aside, the first hand account was, to say the least, a bit alarming, and certainly something that no one wants to have happen (with themselves) on an aircraft.
There is also the issue of Boeing allowing other entities to perform the testing. This was specifically mentioned for a reason. While this may seem trivial, it is not trivial.
I also remember that early news releases stated that airport fire fighters were specifically trained with Li fires, but were unaware that the main batteries on the 787 were Li...this will add another level of equipage/training to the airport mix..
I think that once the general public (ie Senators, Regulators, etc) reads the detailed account of the fire fighters, there will be a call for much higher scrutiny of the fix and certification moving forward. Technicalities aside, the first hand account was, to say the least, a bit alarming, and certainly something that no one wants to have happen (with themselves) on an aircraft.
There is also the issue of Boeing allowing other entities to perform the testing. This was specifically mentioned for a reason. While this may seem trivial, it is not trivial.
I also remember that early news releases stated that airport fire fighters were specifically trained with Li fires, but were unaware that the main batteries on the 787 were Li...this will add another level of equipage/training to the airport mix..
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The fire was declared under control an hour and forty minutes after the initial notification.
Per the NTSB report, after the APU starts, the APU battery must continue to supply power to the APU control electronics. When the JAL battery failed, the APU shut down.
total "management" failure. imho.
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toffeez...
Note the latest 'news'
WASHINGTON (AP) — Firefighters and mechanics tried repeatedly to put out a battery fire aboard a Boeing 787 Dreamliner through smoke so thick they couldn't see the battery, according to documents released Thursday that portray the incident as more serious than previously described.
Boeing 787 battery fire was difficult to control - Yahoo! News
Note the latest 'news'
WASHINGTON (AP) — Firefighters and mechanics tried repeatedly to put out a battery fire aboard a Boeing 787 Dreamliner through smoke so thick they couldn't see the battery, according to documents released Thursday that portray the incident as more serious than previously described.
Boeing 787 battery fire was difficult to control - Yahoo! News