FAA Grounds 787s
Heard a good story last night and I'd be interested to have it confirmed. There is no mechanical stop on the flaps or slats on the 787 (wouldn't have happened if Bigpants or I had been on the design team). I understand a Thomson 787 slat jacks failed to stop recently and wound the slat completely off.
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On rotation, the face of the unprecedentedly-large fan and nacelle intake was tilted to the airflow, which caused unexpected changes to the engine.
Nothing should have been unexpected. .. surge at high alpha has always been a design case... and one particularly requiring flight test clearance!
Nasty and deadly surge on approach caused several fatals contributing to the record brraking protracted development of the F-111 I believe. ..
NB. Intake design is one thing that made Concorde so successful...
Comet problems were as much thinness of skin, type of rivetting & production inspection... as well as mis- understanding of fatigue laws in late '40s ...
Square windows (with very rounded corners) .. always used as an easy quote but very far from the prime factor in those unfortunate days
Yes, agree Volume
MBA's should be banned not just from the aviation industry but from banking post 2008 and best completely re-evaluated as a worthwhile qualification. .. certainly created a nasty tick box culture that allows 'managers' to know nothing at all about the business they're managing be it banking or running a brothel... aha! now that just might be their forte! Try time and motion studying that industry
Nothing should have been unexpected. .. surge at high alpha has always been a design case... and one particularly requiring flight test clearance!
Nasty and deadly surge on approach caused several fatals contributing to the record brraking protracted development of the F-111 I believe. ..
NB. Intake design is one thing that made Concorde so successful...
Comet problems were as much thinness of skin, type of rivetting & production inspection... as well as mis- understanding of fatigue laws in late '40s ...
Square windows (with very rounded corners) .. always used as an easy quote but very far from the prime factor in those unfortunate days
Yes, agree Volume
MBA's should be banned not just from the aviation industry but from banking post 2008 and best completely re-evaluated as a worthwhile qualification. .. certainly created a nasty tick box culture that allows 'managers' to know nothing at all about the business they're managing be it banking or running a brothel... aha! now that just might be their forte! Try time and motion studying that industry
On rotation, the face of the unprecedentedly-large fan and nacelle intake was tilted to the airflow, which caused unexpected changes to the engine.
Nothing should have been unexpected. .. surge at high alpha has always been a design case... and one particularly requiring flight test clearance! Nasty and deadly surge on approach caused several fatals contributing to the record brraking protracted development of the F-111 I believe.
Harryman, that surge had nothing to do with the inlet. It was related to distortion of the engine due to the various G and gyroscopic forces the engine experiences at rotation, which in turn distorted the compressor case resulting in a compressor stall. Pratt claimed afterward that they did have a ground test scheduled that would have uncovered the problem...
That being said, Boeing now has documented procedures that dictate flying test bed testing will be completed prior to installing new (or significantly modified) engines cross wing on a new airplane.
Nothing should have been unexpected. .. surge at high alpha has always been a design case... and one particularly requiring flight test clearance! Nasty and deadly surge on approach caused several fatals contributing to the record brraking protracted development of the F-111 I believe.
Harryman, that surge had nothing to do with the inlet. It was related to distortion of the engine due to the various G and gyroscopic forces the engine experiences at rotation, which in turn distorted the compressor case resulting in a compressor stall. Pratt claimed afterward that they did have a ground test scheduled that would have uncovered the problem...
That being said, Boeing now has documented procedures that dictate flying test bed testing will be completed prior to installing new (or significantly modified) engines cross wing on a new airplane.
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Ok! We live & learn
Being in the industry at the very time was told intake dynamics were behind it. .
And didn't that original intake profile change shape
Being in the industry at the very time was told intake dynamics were behind it. .
And didn't that original intake profile change shape
Last edited by HarryMann; 26th Mar 2014 at 21:41.
And didn't that original intake profile change shape
Nope. The engine in question had a pre-production inlet (i.e. not produced using the production tooling), but the design inlet lines never changed.
BTW, I was on the 777 Propulsion team at the time.
Nope. The engine in question had a pre-production inlet (i.e. not produced using the production tooling), but the design inlet lines never changed.
BTW, I was on the 777 Propulsion team at the time.
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Originally Posted by wikipedia
To address stall issues in certain parts of the flight regime, the engine inlet design was modified in 1965-66, ending with the "Triple Plow I" and "Triple Plow II" designs.[27] The F-111A achieved a speed of Mach 1.3 in February 1965 with an interim intake design.[20][27] Cracks in the F-111's wing attach points were first discovered in 1968 during ground fatigue testing - an F-111 crashed the following year due to this issue. The attach structure required redesign and testing to ensure adequate design and workmanship.[28] Flight testing of the F-111A ran through 1973.[29]
Are we talking about a different aircraft...?
I take it you're talking the F-111. A different kettle of fish (and supersonic capable inlets are a very difficult design challenge).
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manrow
It would appear so, yes:
http://www.faa.gov/about/plans_repor...port_Final.pdf
Back to my original concern: has the certification process for the 787 so far proven to be adequate?
http://www.faa.gov/about/plans_repor...port_Final.pdf
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Back to my original concern: has the certification process for the 787 so far proven to be adequate?
But if you can read English I suggest you dive into this report, it is long and very thorough, it compares 787 with similar aircraft in their initial stages of operation, it uses numbers (some nice graphs) not forums slogans, it addresses certification issues, quality control, redundancies, design architecture, outsourcing, etc. It has nothing on batteries as there will be a separate report about it.
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It is worth noting the following extract from the above report that clearly and unambiguously states that the problems were not due to the new technologies or processes per se, but due to poor implementation.
In each case, the CSRT determined that although the technology was novel, novelty did not cause the in-service issues that triggered the events and the associated challenges discovered during the deep-dive reviews. For example, the CSRT noted one case of internal short-circuiting on an electrical panel’s printed circuit boards. Although a design standard to prevent the short circuiting existed, the issue arose because the design standard was not followed. New technology did not cause the problem in this example; the cause was improper implementation of established design requirements...
The CSRT observed the B787’s use of composites for the primary fuselage and wing structures is unprecedented, but it noted the novel use of composites was not the source of the manufacturing issues it reviewed. Therefore, using the above examples and other similar instances from the deep dive process, the CSRT concluded that novel technology has not significantly contributed to the B787 in-service issues that prompted this review or compromised the safety of the airplane.
In each case, the CSRT determined that although the technology was novel, novelty did not cause the in-service issues that triggered the events and the associated challenges discovered during the deep-dive reviews. For example, the CSRT noted one case of internal short-circuiting on an electrical panel’s printed circuit boards. Although a design standard to prevent the short circuiting existed, the issue arose because the design standard was not followed. New technology did not cause the problem in this example; the cause was improper implementation of established design requirements...
The CSRT observed the B787’s use of composites for the primary fuselage and wing structures is unprecedented, but it noted the novel use of composites was not the source of the manufacturing issues it reviewed. Therefore, using the above examples and other similar instances from the deep dive process, the CSRT concluded that novel technology has not significantly contributed to the B787 in-service issues that prompted this review or compromised the safety of the airplane.
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Ntsb issues recommendations on certification of lithium-ion batteries and emerging te
NTSB release says:
WASHINGTON - The National Transportation Safety Board issued a series of recommendations today related to the evaluation and certification of lithium-ion batteries for use in aircraft systems, as well as the certification of new technology.
The five safety recommendations, all addressed to the Federal Aviation Administration, are derived from the NTSB's ongoing investigation of the January 7, 2013, fire event that occurred in a lithium-ion battery on a Boeing 787 that was parked at Boston Logan Airport.
Investigators found that the battery involved in the Boston 787 fire event showed evidence not just of an internal thermal runaway but that "unintended electrical interactions occurred among the cells, the battery case, and the electrical interfaces between the battery and the airplane."
The 12-page safety recommendation letter said that the processes used in 2006 to support the certification of the lithium-ion battery designed for the 787 were inadequate, in part, because there is no standardized thermal runaway test that's conducted in the environment and conditions that would most accurately reflect how the battery would perform when installed and operated on an in-service airplane.
Further, the NTSB said that because there is no such standardized thermal runaway test, lithium-ion battery designs on airplanes currently in service might not have adequately accounted for the hazards associated with internal short circuiting.
In its examination of the challenges associated with introducing newer technologies into already complex aircraft systems, the NTSB said that including subject matter experts outside of the aviation industry "could further strengthen the aircraft certification process" by ensuring that both the FAA and the aircraft manufacturer have access to the most current research and information related to the developing technology.
To address all of these issues, the NTSB asked the FAA to do the following:
"The history of commercial aviation is one in which emerging technologies have played a key role in enhancing flight safety," said NTSB Acting Chairman Christopher A. Hart. "This is why it's crucial that the process by which these technologies are evaluated and certified is as robust and thorough as possible. These recommendations will take us further in that direction."
The final report on the January 2013 Boston 787 battery fire investigation is estimated to be completed in the fall.
The full text of the safety recommendation letter to the FAA is available at http://go.usa.gov/8XaV.
All of the information and resources the NTSB has released for this investigation can be accessed from the following page: Accident Investigations - Boeing 787.
The five safety recommendations, all addressed to the Federal Aviation Administration, are derived from the NTSB's ongoing investigation of the January 7, 2013, fire event that occurred in a lithium-ion battery on a Boeing 787 that was parked at Boston Logan Airport.
Investigators found that the battery involved in the Boston 787 fire event showed evidence not just of an internal thermal runaway but that "unintended electrical interactions occurred among the cells, the battery case, and the electrical interfaces between the battery and the airplane."
The 12-page safety recommendation letter said that the processes used in 2006 to support the certification of the lithium-ion battery designed for the 787 were inadequate, in part, because there is no standardized thermal runaway test that's conducted in the environment and conditions that would most accurately reflect how the battery would perform when installed and operated on an in-service airplane.
Further, the NTSB said that because there is no such standardized thermal runaway test, lithium-ion battery designs on airplanes currently in service might not have adequately accounted for the hazards associated with internal short circuiting.
In its examination of the challenges associated with introducing newer technologies into already complex aircraft systems, the NTSB said that including subject matter experts outside of the aviation industry "could further strengthen the aircraft certification process" by ensuring that both the FAA and the aircraft manufacturer have access to the most current research and information related to the developing technology.
To address all of these issues, the NTSB asked the FAA to do the following:
- Develop an aircraft-level thermal runaway test to demonstrate safety performance in the presence of an internal short circuit failure
- Require the above test as part of certification of future aircraft designs
- Re-evaluate internal short circuit risk for lithium-ion batteries now in-service
- Develop guidance for thermal runaway test methods
- Include a panel of independent expert consultants early in the certification process for new technologies installed on aircraft
"The history of commercial aviation is one in which emerging technologies have played a key role in enhancing flight safety," said NTSB Acting Chairman Christopher A. Hart. "This is why it's crucial that the process by which these technologies are evaluated and certified is as robust and thorough as possible. These recommendations will take us further in that direction."
The final report on the January 2013 Boston 787 battery fire investigation is estimated to be completed in the fall.
The full text of the safety recommendation letter to the FAA is available at http://go.usa.gov/8XaV.
All of the information and resources the NTSB has released for this investigation can be accessed from the following page: Accident Investigations - Boeing 787.
'R-evaluate internal short circuit risk...' Sounds like the level of risk isn't known with confidence and may be significantly greater than current assessment. So how to deal with this in the current fleet?
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How to deal with lithium ion battery internal short circuit risk ?
Simple, the way it is nearly always done; ignore or obfuscate, better yet blame the pilots.
Dig thru Boeing history on 737 hardcover rudders.
Simple, the way it is nearly always done; ignore or obfuscate, better yet blame the pilots.
Dig thru Boeing history on 737 hardcover rudders.
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Or neurotoxins in cabin air, for that matter (ironically rectified in this very aircraft, but Boeing still adamantly refuse to acknowledge the problem, along with Airbus and all authorities). The industry has a very strong record of blaming crews and letting the manufacturers and authorities, ie. those with connections and money, do whatever they like and suppressing information.
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So how to deal with this in the current fleet?
They dealt with it by enclosing the battery in a steel container. It was tested to prevent any fire or leakages in case of worst thermal runaway or a short circuit.
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one step forward, two steps back?
which begs the question, now that the batteries are encased in steel and thus heavier, do they still provide an advantage over the prior battery technology?
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SKS777FLYER:
I expect thats only on posh 737s with full business class setups....
.......more usual fitting being a paperback rudder
Dig thru Boeing history on 737 hardcover rudders
.......more usual fitting being a paperback rudder
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do they still provide an advantage over the prior battery technology?
