Streak: wasn't the Alaska accident due to a ball-screw actuator that went to full extension and stuck there? What can a pilot do to overcome that sort of failure?
Well, you don't fly it inverted like Denzel Washington did in the movie. The wings are designed to generate lift in one direction to great effect, the other direction, not so much.
Many fellow pilots thought about the problem. The DC-9 Stab is controlled normally by a flight tab. ie airflow over the small wing on the stab forces the stab up and down.
Boeing did not make use of control tabs, they now hydraulically move the control surface using input from the yoke and rudder pedals from the pilot. (anyone remember the rudder hard-over problems/crashes?)
samfp1943 Boeing has already said they are moving the 787's production to South Carolina Not really. The 787 was already built in SC. What Boeing said is that they are no longer going to build the 787 in both Washington State and South Carolina.
Boeing has already said they are moving the 787's production to South Carolina
Not really. The 787 was already built in SC. What Boeing said is that they are no longer going to build the 787 in both Washington State and South Carolina.
The 787-10 was always built in SC. The -8 and -9 versions were built at Everett. The reason the -10 version wasn't built in the state of Washington is that the Dreamlifter could not carry the center barrel section of the 787-10 which is made in an autoclave in SC, and Boeing did not investigate any other mode of transporting this large part to Washington. This would have made a sizeable high-wide load for railroads to handle. [see, railroads] The official reason to consolodate factories is airlines aren't taking deilveries or ordering enough to keep two busy. The unoffical reason is to avoid the unions in Washington State.
MCAS was a poorly thought-out implimentation to add bigger more powerful engines on an existing frame. One (actually several) large customer demanded that Boeing make the MAX fly on the same certificate as the planes they already owned so they would not have to re-train their pilots for one a/c in their fleet. MCAS was created to make the MAX handle in flight exactly like the previous models of 737.
Paul Milenkovic Overmod I was under the understanding that the issue with the MAX was in poorly/incompletely evaluated software and training, not in any jammed actuator issue, and that the fixes to make the aircraft nominally 'airworthy' were relatively slight. This ignores the much greater issue whether any commercial passenger aircraft that is known dynamically unstable in any aspect of normal flight should be granted an airworthiness certificate in the first place -- perhaps it's fortunate for Boeing I don't have a say in this, because I would not, even though I could design all sorts of better ways to kinda-sorta assure operating safety most of the time. It is obvious to me that Boeing would divorce itself as thoroughly from MAX in future marketing as GM might from 8-6-4. Even if touting the same functional advantage for the same reasons. Streak: wasn't the Alaska accident due to a ball-screw actuator that went to full extension and stuck there? What can a pilot do to overcome that sort of failure? There is nothing dynamically or otherwise unstable about the MAX. The software "fix" was to give the same "control feel" to the pilots at high angle of attack near the stall. This would save the airlines who own early 737 models money on retraining pilots for the MAX. There was nothing wrong with the software, either. It was a design choice, however, to let the software feed in a large amount of downward pitch into the elevator trim, which on a jet like this is provided by tilting the whole horizontal stabilizer plane with something called a "jack screw." The reason for doing this with planes that fly close to the sound barrier dates back to Chuck Yeager's first supersonic flight, where he was able to retain control of the plane that lost "elevator effectiveness" at the sound barrier by adjusting the tail-plane "trim." How the designers of Chuck Yeager's plane knew to offer this option may have to do with wind-tunnerl data. It was also a design choice to let the software to repeat and add even more downward pitch. What got messed up is that the software was designed to rely on input from only a single angle-of-attack vane to determine if the plane was near a stall and even needed this correction. That sensor went bad on the two fatal flights. Once this condition happens, I am told, the pilots have seconds to react to this, use the elevator trim switch to countermand the "MCAS" computer system/algorithm and then switch off the electric trim adjustment. On a flight preceding the fateful Lion Air flight, a more experienced pilot who was along for a ride in the cockpit had the presence of mind to order the other pilots to take the corrective action. On the fateful Ethiopian flight, the pilots carried out this action, but they left the engines at full takeoff power, creating a condition where they could not level off even with the electric elevator trim and the MCAS nose-down commands disabled. The whole thing appears to be a combination of sensitivity to a single-point failure in an angle-of-attack vane, giving both the system and the pilots a false stall indication, the what-were-the-engineers-thinking to allow the system to make such large and repeated nose-down corrections, and perhaps, and I stress perhaps, the Ethiopian crew being so overloaded with a false stall warning while they were plummeting to the ground to have the presence of mind to cut engine power. To my knowledge, there has not been on official publication of an accident report on either the Lion Air or Ethiopian aviation disasters. Until then, you, me, and the entire cast of characters on the Web are just guessing. I do have a sense that there might be an "easy" fix -- a combination of looking for agreement of both angle-of-attack sensors, or angle-of-attack agreement with airspeed or some other indication to confirm a stall, a somewhat less aggressive plan for adding nose-down trim, and added crew training. But both Boeing and the FAA are under the microscope of outside scrutiny that it seems "nobody can move."
Overmod I was under the understanding that the issue with the MAX was in poorly/incompletely evaluated software and training, not in any jammed actuator issue, and that the fixes to make the aircraft nominally 'airworthy' were relatively slight. This ignores the much greater issue whether any commercial passenger aircraft that is known dynamically unstable in any aspect of normal flight should be granted an airworthiness certificate in the first place -- perhaps it's fortunate for Boeing I don't have a say in this, because I would not, even though I could design all sorts of better ways to kinda-sorta assure operating safety most of the time. It is obvious to me that Boeing would divorce itself as thoroughly from MAX in future marketing as GM might from 8-6-4. Even if touting the same functional advantage for the same reasons. Streak: wasn't the Alaska accident due to a ball-screw actuator that went to full extension and stuck there? What can a pilot do to overcome that sort of failure?
I was under the understanding that the issue with the MAX was in poorly/incompletely evaluated software and training, not in any jammed actuator issue, and that the fixes to make the aircraft nominally 'airworthy' were relatively slight.
This ignores the much greater issue whether any commercial passenger aircraft that is known dynamically unstable in any aspect of normal flight should be granted an airworthiness certificate in the first place -- perhaps it's fortunate for Boeing I don't have a say in this, because I would not, even though I could design all sorts of better ways to kinda-sorta assure operating safety most of the time.
It is obvious to me that Boeing would divorce itself as thoroughly from MAX in future marketing as GM might from 8-6-4. Even if touting the same functional advantage for the same reasons.
There is nothing dynamically or otherwise unstable about the MAX. The software "fix" was to give the same "control feel" to the pilots at high angle of attack near the stall. This would save the airlines who own early 737 models money on retraining pilots for the MAX.
There was nothing wrong with the software, either. It was a design choice, however, to let the software feed in a large amount of downward pitch into the elevator trim, which on a jet like this is provided by tilting the whole horizontal stabilizer plane with something called a "jack screw." The reason for doing this with planes that fly close to the sound barrier dates back to Chuck Yeager's first supersonic flight, where he was able to retain control of the plane that lost "elevator effectiveness" at the sound barrier by adjusting the tail-plane "trim." How the designers of Chuck Yeager's plane knew to offer this option may have to do with wind-tunnerl data.
It was also a design choice to let the software to repeat and add even more downward pitch. What got messed up is that the software was designed to rely on input from only a single angle-of-attack vane to determine if the plane was near a stall and even needed this correction. That sensor went bad on the two fatal flights.
Once this condition happens, I am told, the pilots have seconds to react to this, use the elevator trim switch to countermand the "MCAS" computer system/algorithm and then switch off the electric trim adjustment.
On a flight preceding the fateful Lion Air flight, a more experienced pilot who was along for a ride in the cockpit had the presence of mind to order the other pilots to take the corrective action. On the fateful Ethiopian flight, the pilots carried out this action, but they left the engines at full takeoff power, creating a condition where they could not level off even with the electric elevator trim and the MCAS nose-down commands disabled.
The whole thing appears to be a combination of sensitivity to a single-point failure in an angle-of-attack vane, giving both the system and the pilots a false stall indication, the what-were-the-engineers-thinking to allow the system to make such large and repeated nose-down corrections, and perhaps, and I stress perhaps, the Ethiopian crew being so overloaded with a false stall warning while they were plummeting to the ground to have the presence of mind to cut engine power.
To my knowledge, there has not been on official publication of an accident report on either the Lion Air or Ethiopian aviation disasters. Until then, you, me, and the entire cast of characters on the Web are just guessing.
I do have a sense that there might be an "easy" fix -- a combination of looking for agreement of both angle-of-attack sensors, or angle-of-attack agreement with airspeed or some other indication to confirm a stall, a somewhat less aggressive plan for adding nose-down trim, and added crew training. But both Boeing and the FAA are under the microscope of outside scrutiny that it seems "nobody can move."
https://www.youtube.com/watch?v=TlinocVHpzk
Never too old to have a happy childhood!
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
samfp1943 7j43k From the NTSB report on Alaska Flight 261 (January 31, 2000): "The National Transportation Safety Board determines that the probable cause of this accident was a loss of airplane pitch control resulting from the in-flight failure of the horizontal stabilizer trim system jackscrew assembly's acme nut threads. The thread failure was caused by excessive wear resulting from Alaska Airlines' insufficient lubrication of the jackscrew assembly. "https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR0201.pdf Ed We are sort of 'wandering out into the weeds' on this Thread. Specifically, the "Problems' with the B737 MAX type aircraft, came out of two crashes of the type. First was in October of 2018 and involved a Lion Air Flt.610[189 souls died]. Second was March of 2019 and involved an Ethopian Air Line Flt.302[157 souls died] . In the aftermath, of these two (type-8)crashes; use of these aircraft was put on hold. Of course there was a 'media storm' and the finger pointing began. The FAA was sighted for being 'too cozy' with Boeing in the certification process, and Boeing caught much 'flak' for the apparent failure of their 'MCAS' systems. FTL[below] :"...After the second tragedy, the 737 Max was grounded by regulators because an anti-stall system known as the Maneuvering Characteristics Augmentation System (MCAS) was implicated in both crashes..."* *Linked from https://www.independent.co.uk/travel/news-and-advice/boeing-737-max-crash-aircraft-stall-grounded-pilots-blamed-a9111646.html author:Travel Correspondent @SimonCalderFriday 20 September 2019 07:25 Mr. S. Calder is a former pilot and makes the case that 'Pilot Training' was a major issue with the aircraft. Another issue thaqt surfaced at Boeing/Spirit was that the MCAS system was poorly engineered, and that wound up costing several company execs their jobs. After a couple of 'false starts' it was a good thing to see them moving those partially completed aircraft out.. Now hopefully, some of the many laid off workers can go back to work, and the area economy will start to bounce back? Here is a linked article from the NYTimes @ https://www.nytimes.com/interactive/2019/business/boeing-737-crashes.html It was not under a paywall when I put the link in.
7j43k From the NTSB report on Alaska Flight 261 (January 31, 2000): "The National Transportation Safety Board determines that the probable cause of this accident was a loss of airplane pitch control resulting from the in-flight failure of the horizontal stabilizer trim system jackscrew assembly's acme nut threads. The thread failure was caused by excessive wear resulting from Alaska Airlines' insufficient lubrication of the jackscrew assembly. "https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR0201.pdf Ed
From the NTSB report on Alaska Flight 261 (January 31, 2000):
"The National Transportation Safety Board determines that the probable cause of this accident was a loss of airplane pitch control resulting from the in-flight failure of the horizontal stabilizer trim system jackscrew assembly's acme nut threads. The thread failure was caused by excessive wear resulting from Alaska Airlines' insufficient lubrication of the jackscrew assembly.
"https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR0201.pdf
Ed
We are sort of 'wandering out into the weeds' on this Thread.
Specifically, the "Problems' with the B737 MAX type aircraft, came out of two crashes of the type. First was in October of 2018 and involved a Lion Air Flt.610[189 souls died]. Second was March of 2019 and involved an Ethopian Air Line Flt.302[157 souls died] .
In the aftermath, of these two (type-8)crashes; use of these aircraft was put on hold. Of course there was a 'media storm' and the finger pointing began. The FAA was sighted for being 'too cozy' with Boeing in the certification process, and Boeing caught much 'flak' for the apparent failure of their 'MCAS' systems.
FTL[below] :"...After the second tragedy, the 737 Max was grounded by regulators because an anti-stall system known as the Maneuvering Characteristics Augmentation System (MCAS) was implicated in both crashes..."*
*Linked from https://www.independent.co.uk/travel/news-and-advice/boeing-737-max-crash-aircraft-stall-grounded-pilots-blamed-a9111646.html
author:Travel Correspondent @SimonCalderFriday 20 September 2019 07:25
Mr. S. Calder is a former pilot and makes the case that 'Pilot Training' was a major issue with the aircraft. Another issue thaqt surfaced at Boeing/Spirit was that the MCAS system was poorly engineered, and that wound up costing several company execs their jobs.
After a couple of 'false starts' it was a good thing to see them moving those partially completed aircraft out.. Now hopefully, some of the many laid off workers can go back to work, and the area economy will start to bounce back?
Here is a linked article from the NYTimes @ https://www.nytimes.com/interactive/2019/business/boeing-737-crashes.html
It was not under a paywall when I put the link in.
If you wanted to wander out into YOUR weeds about the 737 crashes (an excellent choice), why did you quote my out in the weeds comment about the crash of 261?
Should you not have quoted something referring to your own weed excursion?
"The National Transportation Safety Board determines that the probable cause of this accident was a loss of airplane pitch control resulting from the in-flight failure of the horizontal stabilizer trim system jackscrew assembly's acme nut threads. The thread failure was caused by excessive wear resulting from Alaska Airlines' insufficient lubrication of the jackscrew assembly."
https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR0201.pdf
samfp1943 Boeing has already said they are moving the 787's production to South Carolina
An "expensive model collector"
Overmod Streak: wasn't the Alaska accident due to a ball-screw actuator that went to full extension and stuck there? What can a pilot do to overcome that sort of failure?
Unfortunately fly at speed that you can control aircraft. But then slowing for landing ? ? ?
The stab does have a hydralic assist for stab down only that is checked by pre departure flight control check. An annunciator notes stab full down. So if stab does not return to normal you cannot lift off on takeoffs, I believe that there has been a couple aborted take offs due to jammed stabs.
The aerilons and rudder also have flight tabs. We considered system very robust and not subject to hydraulic operation. Very safe. Most Boeings use hydraulic control.
Runaway stablizers is one of the more critical emergency situations a pilot can have happen. Jammed stab at high speeds can be another. Alaska air DC-9 jammed stab accident. The controls for moving the stab are pickle switches on each poilot's yoke and usually on the center console. As well usually some kind of manual way to move the stab.
Douglas had 2 suitcase handle moved together to operate hydraulic. Boeing had a manual wheel on pedesal each side that pilot could use to move or grab when a runaway started. But trim power was slow on auto pilot and pilot pickel switches fast. Pilot could grab wheel to stop runaway until CB could be pulled.
Early 737s have wheel but not sure about max. Just a guess but appears not. I do not like that concept at all.
kgbw49 Apparently the "737-8" could be certified to fly as early as November. https://onemileatatime.com/boeing-737-8/
Apparently the "737-8" could be certified to fly as early as November.
https://onemileatatime.com/boeing-737-8/
From the link provided by kgbw49 FTL:"...I would imagine that this was coordinated with Boeing, though at the time Boeing’s press release continued to use the full “MAX” branding. To my knowledge this Enter Air press release is the first one where Boeing specifically mentions the new branding.
If Boeing were to rebrand the 737 MAX, the new naming convention makes a lot of sense. It’s the same as how the 787 variants are known as the 787-8, 787-9, and 787-10. Similarly, the new 737 variants could be known as the 737-7, 737-8, 737-9, and 737-10 (while older generation 737s were the 737-700, 737-800, 737-900, etc.)..."
THanks, kgbw49 for the linkled story Living in the Wichita area, we are effected constantly by the employment vaugeries of Spirit Aviation Corp's (nee: Boeing Corp) 'roller coaster' of hiring cycles. As a result of all the recent 'problems' surrounding the 737 ( and its varients) . This area has been riding an economic roller coaster, which always seems to be one of the problems within the Aviation sector (?).
So any sign of a change in that sector is always welcome. Specifically, the 737's fuselages riding out of town on their specialty transport cars, can be a welcome sign that things here are picking up (Spirit's employees, when the plant is active, amount to several thousands, on the job.)
Spirit has also has built the cockpit section of the 747's; which is winding down; the 787's cockpits are also built here, and either flown out,(on the 'Dreamlifter' fleet of freighters) or shipped out in special rail cars (?) So with their local railservicer as BNSF, it is an integral part of Spirit/Boeing's aircraft production supply operation. Not to mention a point of interst to local rail fans.
Went past the Spirit Aviation Plant this morning; Looked like about 5 fuselages were loaded and in position to move out; first time in a long time that there have been multiple outbound.
After months of seeing their production just going under tarps; and a large number under 'tarps' along the runways at McConnell. It was gratifying to see them starting to move them out. There have been no public announcements of how their production will start up, or when?
The one thing about it; they'll all need a trainride to Northwest before they actually fly. Or maybe, they'll do something different with them?
Boeing has already said they are moving the 787's production to South Carolina...So who knows, how the renewed production on the 737's will shake out. Since the late 1960's the Boeing aircraft have been a component of traffic on BNSF.
Will be interesting to see how it all will work out, and on which railroads?
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