737 Stuck Manual Trim Technique
Thread Starter
You cannot remove the fact that this procedure was once published, that is an established fact. Removal of it from recent manuals cannot change the reality that is already proven. History tells us there never was anything seen wrong with the trim system or it's procedures in the 60 years before this - suddenly finding something there now is far too close to 20/20 far-too-clever hindsight.
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Total topsy-turvey irrational logic, typical of so much of the irrational criticism here.
You cannot remove the fact that this procedure was once published, that is an established fact. Removal of it from recent manuals cannot change the reality that is already proven. History tells us there never was anything seen wrong with the trim system or it's procedures in the 60 years before this - suddenly finding something there now is far too close to 20/20 far-too-clever hindsight.
You cannot remove the fact that this procedure was once published, that is an established fact. Removal of it from recent manuals cannot change the reality that is already proven. History tells us there never was anything seen wrong with the trim system or it's procedures in the 60 years before this - suddenly finding something there now is far too close to 20/20 far-too-clever hindsight.
At the end of the day we don't know why it was removed so it's speculation on both sides.
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[QUOTE=MurphyWasRight;10447583]Interesting experiment would be run the scenario and see if AND does work, which my understanding is that it should not due to column cutout switches. If it does the SIM has this backwards somewhere. Also to notice is whether electrical trim re-appears all at once or begins to work slowly at some point.
Useful discussion of stab screwjack loading here: https://www.satcom.guru/2019/04/stab...and-range.html
Would suggest that the effect we observed was correct for stab in (gross mis trimmed) AND position (stab leading edge UP) and aft elevator applied. We didn't try AND electric trim, just ANU electric to avoid impending terrain impact with our particular scenario.
During the described scenario, the reactivation or 'release' of the stab trim wheels was 'progressive' as the aft elevator back pressure/position from aft stop was released, certainly not a 'switch' like effect.
An aside, both the devices mentioned also have a faults for 'stab trim brake failure', this runs the stab according to aerodynamic loading on the stabiliser. A slow and insidious failure... requires NNC memory item for 'if runaway continues' ... stab trim wheel 'grasp and hold', very easily stopped with the palm of the hand on the opposite trim wheel for this simulated fault. I note this in passing, as not all FFS that I've used have such an expansive fault list.
Useful discussion of stab screwjack loading here: https://www.satcom.guru/2019/04/stab...and-range.html
Would suggest that the effect we observed was correct for stab in (gross mis trimmed) AND position (stab leading edge UP) and aft elevator applied. We didn't try AND electric trim, just ANU electric to avoid impending terrain impact with our particular scenario.
During the described scenario, the reactivation or 'release' of the stab trim wheels was 'progressive' as the aft elevator back pressure/position from aft stop was released, certainly not a 'switch' like effect.
An aside, both the devices mentioned also have a faults for 'stab trim brake failure', this runs the stab according to aerodynamic loading on the stabiliser. A slow and insidious failure... requires NNC memory item for 'if runaway continues' ... stab trim wheel 'grasp and hold', very easily stopped with the palm of the hand on the opposite trim wheel for this simulated fault. I note this in passing, as not all FFS that I've used have such an expansive fault list.
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MurphyWasRight
To their credit, I would assume that the runaway trim procedure was written considering the entire flight envelope. Statistically this would be more likely to occur at altitude, rather than close to the ground, where the aircraft spends a limited time. Not a great assumption, but in the normal scenario, there would be more time for recovery procedures.
The fact that MCAS triggered shortly after takeoff, made the outcome diabolical, when the other factors came into play. If MCAS triggered at altitude, the outcome would probably be more benign, with time for the yo-yo unloading technique.
Perhaps this lack of foresight led to the blandness of the emergency AD. Prior to ET302, almost nobody would have believed that the same outcome could be triggered by two consecutive AOA sensor failures at the same stage of flight, and disaster still not be prevented by the suggested actions.
Agreed, before Lion Air suggesting that a new undocumented feature relying on a single sensor would have a death wish would have indeed been laughable.
Truly tragic is the CYA manner the AD was written, rather than simple and forcefull checklist for MCAS misbehave.
Would be interesting to hear why mention of the 'yo yo' technique was removed along the way.
Additional point:
A true trim runaway (stuck relay/whatever) at high speed could get into this state before the pilots recognized and cut out the trim motors, so hard to see how this is unimaginable. About 5 seconds or so appears to do the trick.
Truly tragic is the CYA manner the AD was written, rather than simple and forcefull checklist for MCAS misbehave.
Would be interesting to hear why mention of the 'yo yo' technique was removed along the way.
Additional point:
A true trim runaway (stuck relay/whatever) at high speed could get into this state before the pilots recognized and cut out the trim motors, so hard to see how this is unimaginable. About 5 seconds or so appears to do the trick.
The fact that MCAS triggered shortly after takeoff, made the outcome diabolical, when the other factors came into play. If MCAS triggered at altitude, the outcome would probably be more benign, with time for the yo-yo unloading technique.
Perhaps this lack of foresight led to the blandness of the emergency AD. Prior to ET302, almost nobody would have believed that the same outcome could be triggered by two consecutive AOA sensor failures at the same stage of flight, and disaster still not be prevented by the suggested actions.
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MurphyWasRight
To their credit, I would assume that the runaway trim procedure was written considering the entire flight envelope. Statistically this would be more likely to occur at altitude, rather than close to the ground, where the aircraft spends a limited time. Not a great assumption, but in the normal scenario, there would be more time for recovery procedures.
The fact that MCAS triggered shortly after takeoff, made the outcome diabolical, when the other factors came into play. If MCAS triggered at altitude, the outcome would probably be more benign, with time for the yo-yo unloading technique.
Perhaps this lack of foresight led to the blandness of the emergency AD. Prior to ET302, almost nobody would have believed that the same outcome could be triggered by two consecutive AOA sensor failures at the same stage of flight, and disaster still not be prevented by the suggested actions.
To their credit, I would assume that the runaway trim procedure was written considering the entire flight envelope. Statistically this would be more likely to occur at altitude, rather than close to the ground, where the aircraft spends a limited time. Not a great assumption, but in the normal scenario, there would be more time for recovery procedures.
The fact that MCAS triggered shortly after takeoff, made the outcome diabolical, when the other factors came into play. If MCAS triggered at altitude, the outcome would probably be more benign, with time for the yo-yo unloading technique.
Perhaps this lack of foresight led to the blandness of the emergency AD. Prior to ET302, almost nobody would have believed that the same outcome could be triggered by two consecutive AOA sensor failures at the same stage of flight, and disaster still not be prevented by the suggested actions.
Takeoff/landing is much more dynamic than cruise so more likely for something to fail so statistics could be misleading.
Sadly the AOA sensor failures were not at same stage of flight, Lion Air had a bad sensor for the entire penultimate flight, which if corrected would have prevented the Lion air accident.
ET had an event at takeoff, either a bird strike or a latent fault literally shaken loose.
Both of course lead to disaster shortly after takeoff when MCAS was unleashed.
Hard to get past the feeling that the 'blandness' (good description btw) was part of an effort to preserve the "no changes no training" company line on the MAX.
Thread Starter
"Blandness"
It is surely essential that checklists and ADs are bland, that is part of their nature. It is not appropriate to used nuanced language in these, just bare statements of fact. It is up to pilots to nuance them, where they do it in crewroom discussion or in flight.
The AD following the Lionair accident has been criticised for understating the effects and environment caused by the associated additional warnings, a 'mere' list of contrary indications, stick shaker, apparently unconnected warnings etc understating the confusion and bedlam of the real event.
Guys, we're Professional pilots, it's up to us to use our Professional systems knowlege and imagination to read past Boeing's list of cold facts to picture what the reality is like. It is most certainly not appropriate for Boeing to go injecting emotions or human preceptions/reactions into a checklist.
Surge-Limit-Stall doesn't start with 'If there's a big scary noise from the engine that makes you jump...' does it? Where is the nuanced language in the V1 reject actions? Or a rapid depressurisation? It's just a list of facts. If you're not imaginative enough to read between the lines and visualise and prepare for the BANG! and WHOOOSH! deafening noise and agonising barotrauma that might go with it then stick to reading the daily mail on a train, why would/should Boeing patronise you with emotional language?
To be fair I suspect most of those calling for such explanations aren't Professional pilots. At least, I sure hope so!
It is surely essential that checklists and ADs are bland, that is part of their nature. It is not appropriate to used nuanced language in these, just bare statements of fact. It is up to pilots to nuance them, where they do it in crewroom discussion or in flight.
The AD following the Lionair accident has been criticised for understating the effects and environment caused by the associated additional warnings, a 'mere' list of contrary indications, stick shaker, apparently unconnected warnings etc understating the confusion and bedlam of the real event.
Guys, we're Professional pilots, it's up to us to use our Professional systems knowlege and imagination to read past Boeing's list of cold facts to picture what the reality is like. It is most certainly not appropriate for Boeing to go injecting emotions or human preceptions/reactions into a checklist.
Surge-Limit-Stall doesn't start with 'If there's a big scary noise from the engine that makes you jump...' does it? Where is the nuanced language in the V1 reject actions? Or a rapid depressurisation? It's just a list of facts. If you're not imaginative enough to read between the lines and visualise and prepare for the BANG! and WHOOOSH! deafening noise and agonising barotrauma that might go with it then stick to reading the daily mail on a train, why would/should Boeing patronise you with emotional language?
To be fair I suspect most of those calling for such explanations aren't Professional pilots. At least, I sure hope so!
came across this thread, relevant quote from it below. Obviously no way of knowing if genuine or not, but given what else has been posted on the difficulty of operating the manual trim wheel, it does sound plausible.
Shutdown caused Boeing crash. - Page 4 - International Skeptics Forum
Quote...
"I agree it's a flawed design. And I used to work there. I'm glad I don't now.
Regarding the trim wheels: When the NG was being introduced, I happened to be the Lead Engineer in charge of them and a whole lot of other stuff. There were some issues. The new display system created a pinch point between the dash and the wheel. We had to make the wheel smaller. And the new trim motor resulted in the wheel, which is directly connected to the stabilizer by a long cable, springing back when electric trim was used. It was an undamped mass on the end of a spring. We had to add a damper.
Result: Depending on the flight conditions, the force to manually trim can be extremely high. We set up a test rig and a very fit female pilot could barely move it.
As I said, I'm glad I'm no longer there."
Alchad
https://www.pprune.org/rumours-news/619272-ethiopian-airliner-down-africa.html#post10453797
Shutdown caused Boeing crash. - Page 4 - International Skeptics Forum
Quote...
"I agree it's a flawed design. And I used to work there. I'm glad I don't now.
Regarding the trim wheels: When the NG was being introduced, I happened to be the Lead Engineer in charge of them and a whole lot of other stuff. There were some issues. The new display system created a pinch point between the dash and the wheel. We had to make the wheel smaller. And the new trim motor resulted in the wheel, which is directly connected to the stabilizer by a long cable, springing back when electric trim was used. It was an undamped mass on the end of a spring. We had to add a damper.
Result: Depending on the flight conditions, the force to manually trim can be extremely high. We set up a test rig and a very fit female pilot could barely move it.
As I said, I'm glad I'm no longer there."
Alchad
https://www.pprune.org/rumours-news/619272-ethiopian-airliner-down-africa.html#post10453797
Last edited by FlexibleResponse; 23rd Apr 2019 at 23:20.
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"Blandness"
It is surely essential that checklists and ADs are bland, that is part of their nature. It is not appropriate to used nuanced language in these, just bare statements of fact. It is up to pilots to nuance them, where they do it in crewroom discussion or in flight.
The AD following the Lionair accident has been criticised for understating the effects and environment caused by the associated additional warnings, a 'mere' list of contrary indications, stick shaker, apparently unconnected warnings etc understating the confusion and bedlam of the real event.
Guys, we're Professional pilots, it's up to us to use our Professional systems knowlege and imagination to read past Boeing's list of cold facts to picture what the reality is like. It is most certainly not appropriate for Boeing to go injecting emotions or human preceptions/reactions into a checklist.
Surge-Limit-Stall doesn't start with 'If there's a big scary noise from the engine that makes you jump...' does it? Where is the nuanced language in the V1 reject actions? Or a rapid depressurisation? It's just a list of facts. If you're not imaginative enough to read between the lines and visualise and prepare for the BANG! and WHOOOSH! deafening noise and agonising barotrauma that might go with it then stick to reading the daily mail on a train, why would/should Boeing patronise you with emotional language?
To be fair I suspect most of those calling for such explanations aren't Professional pilots. At least, I sure hope so!
It is surely essential that checklists and ADs are bland, that is part of their nature. It is not appropriate to used nuanced language in these, just bare statements of fact. It is up to pilots to nuance them, where they do it in crewroom discussion or in flight.
The AD following the Lionair accident has been criticised for understating the effects and environment caused by the associated additional warnings, a 'mere' list of contrary indications, stick shaker, apparently unconnected warnings etc understating the confusion and bedlam of the real event.
Guys, we're Professional pilots, it's up to us to use our Professional systems knowlege and imagination to read past Boeing's list of cold facts to picture what the reality is like. It is most certainly not appropriate for Boeing to go injecting emotions or human preceptions/reactions into a checklist.
Surge-Limit-Stall doesn't start with 'If there's a big scary noise from the engine that makes you jump...' does it? Where is the nuanced language in the V1 reject actions? Or a rapid depressurisation? It's just a list of facts. If you're not imaginative enough to read between the lines and visualise and prepare for the BANG! and WHOOOSH! deafening noise and agonising barotrauma that might go with it then stick to reading the daily mail on a train, why would/should Boeing patronise you with emotional language?
To be fair I suspect most of those calling for such explanations aren't Professional pilots. At least, I sure hope so!
Totally agree that emotional language has no place in a checklist.
However proficiency at reading between the lines might be especially difficult for pilots with English as a second language,certainly hard to test for.
I believe that lack of systems knowledge is a key issue, to train and test the ability to apply it in real situations is a thorny problem.
It is probably up there with lack practice of manual flying skills as real concerns.
.
The 'blandness' comment on the emergency AD had to do with the possible attempt to minimize the MCAS issue to maintain the claim that existing procedures were sufficient.
What was missing was the clear 'list of facts' and actions, with some of the critical items presented as a note at the end.
I am not at all a pilot but have a lot of experience in analysing problems from an outsider viewpoint.
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737 Max simulator revised for better simulation of manual trim
On 2019-09-15, AFP quotes Boeing as stating:
Do we have an authoritative source on if the changes make the simulator's wheel harder or softer, by what amount, and what part of the flight envelope are affected?
Boeing has made corrections to the 737 MAX simulator software and has provided additional information to device operators to ensure that the simulator experience is representative across different flight conditions
changes will improve the simulation of force loads on the manual trim wheel
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I can confirm that Mechatronix NG simulator we have does not have loading to the trim wheels. Very disconcerting when you try the scenario and the F/O can wind in full Nose down on you.
And no, it's not recoverable in that state. Very sobering.
And no, it's not recoverable in that state. Very sobering.
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I know, test flights are there to collect parameters that you can analyze, replicate in the sim, and so on.
But given that MCAS was (not) really tested before and nobody even knew it was a new thing, I hope that Boing has gone to the limits to prove that it is fixed and that all those "undertrained, third world, below average, slow procedure followers" will be able to "just keep flying" if MCAS is active again. Or, even worst, it doesn't activate anymore when it was necessary (since I consider it existed to do something important and wasn't created just to keep engineers doing something in the spare time).
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Also practiced this when transitioning to the B737-200
but this practice was not in the programme when transitioning to the B737-400 and B737-800
‘Also practiced this when transitioning to the B737-200
but this practice was not in the programme when transitioning to the B737-400 and B737-800.’
Would the procedure have worked in the simulation of the later aircraft, perhaps not #90. If not then why no questions / safety report to Boeing ; who knew, when, and why no FAA intervention; certification or training. What are the effects of increased tail area on this drill.
Would - will the procedure work in later aircraft; i.e. would crew’s in these aircraft have similar difficulties in managing a trim runaway, as did those in the Max accidents when using the runaway drill for MCAS trim problems.
but this practice was not in the programme when transitioning to the B737-400 and B737-800.’
Would the procedure have worked in the simulation of the later aircraft, perhaps not #90. If not then why no questions / safety report to Boeing ; who knew, when, and why no FAA intervention; certification or training. What are the effects of increased tail area on this drill.
Would - will the procedure work in later aircraft; i.e. would crew’s in these aircraft have similar difficulties in managing a trim runaway, as did those in the Max accidents when using the runaway drill for MCAS trim problems.
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Flight crew error statistics support your statement, but what is the cure?
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Pretty much the same aircraft as the MAX, same type rating, no extra flight crew training required, about same price, similar size and load capability, etc. etc.
Rate of flight crew error (well proven over two decades) causing non-survivable crash is roughly two orders of magnitude lower than that of the MAX. Flew for a decade without a crew-error crash.
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If we're looking at statistics, might I suggest the 737-NG as the cure ?
Pretty much the same aircraft as the MAX, same type rating, no extra flight crew training required, about same price, similar size and load capability, etc. etc.
Rate of flight crew error (well proven over two decades) causing non-survivable crash is roughly two orders of magnitude lower than that of the MAX. Flew for a decade without a crew-error crash.
Pretty much the same aircraft as the MAX, same type rating, no extra flight crew training required, about same price, similar size and load capability, etc. etc.
Rate of flight crew error (well proven over two decades) causing non-survivable crash is roughly two orders of magnitude lower than that of the MAX. Flew for a decade without a crew-error crash.
Last edited by Fly Aiprt; 23rd May 2019 at 20:52. Reason: Typo
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https://www.seattletimes.com/busines...-within-weeks/
FAA will move first to approve the Boeing 737 MAX to fly again, possibly within weeks
May 23, 2019 at 4:00 pm Updated May 23, 2019 at 4:35 pm
By Dominic Gates
Seattle Times aerospace reporter
FORT WORTH, TEXAS — During a break from an international gathering of air safety regulators from around the world, the head of the Federal Aviation Administration (FAA) made clear Thursday that his agency will move first to lift the order grounding Boeing’s 737 MAX and that such clearance could come as early as late June.
“When we get to the point where we can lift this order, we will do it alone,” said Acting FAA Administrator Dan Elwell, explaining that because the U.S. certified the original design, it must be first to certify the Boeing software fix for the flight control system that went awry on the fatal Lion Air and Ethiopian Airlines flights.
Safety regulators elsewhere will make their own decisions after looking at the FAA’s data, he said. Some will accept it, while “other countries have already decided they will not only review our work but look at some other things of interest to them.”
Relations between foreign aviation-safety agencies and the FAA have been strained by two MAX crashes in five months, the FAA’s slowness to ground the planes and subsequent questions about the rigor and independence of the agency’s certification process.
“There will be some kind of lag,” he said. “Every country has their own process. They never just blindly accept what we do.”
Ali Bahrami, the FAA’s head of aviation safety, said some countries are seeking more detail on the basis of the assumptions that go into the FAA’s system safety analysis.
Elwell said the FAA must finish its system safety analysis of the problematic flight control system, called MCAS (Maneuvering Characteristics Augmentation System), and conduct a series of flight tests followed by a “robust analysis” of the data the test flights generate.
He resisted citing any timeline for this work, saying that “the safety of the 737 MAX, that’s my only target.”
However, he also said that once Boeing submits its finalized software update, “we generally think our work should take about three to four weeks.”
Boeing is expected to submit its final software fix within days. The manufacturer said last week its update was completed, and it was expected to be submitted by now. So this suggests that if no further delays happen, it’s possible the FAA could give clearance to fly by the end of June.
The MAX operators in the U.S. — American, Southwest and United — would then need some time to install the update on their grounded aircraft and to do mandated training with all their 737 pilots before putting the MAX back in passenger service as early as late August.
Elwell warned that if FAA technical specialists find issues with Boeing’s fixes, that could cause more delay.
Separately, a Technical Advisory Board consisting of FAA and NASA specialists who are not working directly on the project will independently review the FAA’s certification of the MCAS fix and “if they find something they want us to look closer at, we’ll do it,” Elwell said.
Elwell insisted that “the public can trust that the FAA will not let the 737 MAX fly again in the U.S. until it is safe to do so.”
He said his agency is dedicated to making the U.S. “the safest possible airspace in the world” and pointed to the safety record of the past two decades: 90 million flights by U.S. registered airliners, carrying 7 billion passengers, with just a single fatality, after an engine blowout broke a passenger window on a Southwest Airlines jet last fall.
“Aviation is still the safest mode of transportation on the planet,” Elwell said. “Once the 737 MAX is safely flying again, it might take some time, but I think the public will become comfortable.”
In interviews Thursday, Elwell reiterated his view expressed in Congressional hearings that once the accident investigations in Indonesia and Ethiopia are complete, the cause of the two accidents will be revealed as “a chain of events” and that “the procedures the pilots did or didn’t do” as well as the maintenance of the aircraft will have to be scrutinized.
Elwell’s comment about potential maintenance issues is likely a reference to the Lion Air accident. In the two flights of that same jet immediately prior to the crash last October, the sensor that triggered MCAS gave false signals — one sensor was replaced — and caused severe flight control problems, though the plane was still cleared to fly.
However, Elwell said Boeing’s MCAS flight control software is “the issue that links these two horrific accidents.”
“We are going to mitigate that,” he said.
Elwell said after the meeting of regulators from 33 nations ended that the gathering had been “comprehensive and constructive.”
“When we broke, there was a great buzz” among the delegates, said Elwell. “I definitely got the impression that what they had heard was extremely helpful to them.
Dominic Gates: 206-464-2963 or [email protected]; on Twitter: @dominicgates.
May 23, 2019 at 4:00 pm Updated May 23, 2019 at 4:35 pm
By Dominic Gates
Seattle Times aerospace reporter
FORT WORTH, TEXAS — During a break from an international gathering of air safety regulators from around the world, the head of the Federal Aviation Administration (FAA) made clear Thursday that his agency will move first to lift the order grounding Boeing’s 737 MAX and that such clearance could come as early as late June.
“When we get to the point where we can lift this order, we will do it alone,” said Acting FAA Administrator Dan Elwell, explaining that because the U.S. certified the original design, it must be first to certify the Boeing software fix for the flight control system that went awry on the fatal Lion Air and Ethiopian Airlines flights.
Safety regulators elsewhere will make their own decisions after looking at the FAA’s data, he said. Some will accept it, while “other countries have already decided they will not only review our work but look at some other things of interest to them.”
Relations between foreign aviation-safety agencies and the FAA have been strained by two MAX crashes in five months, the FAA’s slowness to ground the planes and subsequent questions about the rigor and independence of the agency’s certification process.
“There will be some kind of lag,” he said. “Every country has their own process. They never just blindly accept what we do.”
Ali Bahrami, the FAA’s head of aviation safety, said some countries are seeking more detail on the basis of the assumptions that go into the FAA’s system safety analysis.
Elwell said the FAA must finish its system safety analysis of the problematic flight control system, called MCAS (Maneuvering Characteristics Augmentation System), and conduct a series of flight tests followed by a “robust analysis” of the data the test flights generate.
He resisted citing any timeline for this work, saying that “the safety of the 737 MAX, that’s my only target.”
However, he also said that once Boeing submits its finalized software update, “we generally think our work should take about three to four weeks.”
Boeing is expected to submit its final software fix within days. The manufacturer said last week its update was completed, and it was expected to be submitted by now. So this suggests that if no further delays happen, it’s possible the FAA could give clearance to fly by the end of June.
The MAX operators in the U.S. — American, Southwest and United — would then need some time to install the update on their grounded aircraft and to do mandated training with all their 737 pilots before putting the MAX back in passenger service as early as late August.
Elwell warned that if FAA technical specialists find issues with Boeing’s fixes, that could cause more delay.
Separately, a Technical Advisory Board consisting of FAA and NASA specialists who are not working directly on the project will independently review the FAA’s certification of the MCAS fix and “if they find something they want us to look closer at, we’ll do it,” Elwell said.
Elwell insisted that “the public can trust that the FAA will not let the 737 MAX fly again in the U.S. until it is safe to do so.”
He said his agency is dedicated to making the U.S. “the safest possible airspace in the world” and pointed to the safety record of the past two decades: 90 million flights by U.S. registered airliners, carrying 7 billion passengers, with just a single fatality, after an engine blowout broke a passenger window on a Southwest Airlines jet last fall.
“Aviation is still the safest mode of transportation on the planet,” Elwell said. “Once the 737 MAX is safely flying again, it might take some time, but I think the public will become comfortable.”
In interviews Thursday, Elwell reiterated his view expressed in Congressional hearings that once the accident investigations in Indonesia and Ethiopia are complete, the cause of the two accidents will be revealed as “a chain of events” and that “the procedures the pilots did or didn’t do” as well as the maintenance of the aircraft will have to be scrutinized.
Elwell’s comment about potential maintenance issues is likely a reference to the Lion Air accident. In the two flights of that same jet immediately prior to the crash last October, the sensor that triggered MCAS gave false signals — one sensor was replaced — and caused severe flight control problems, though the plane was still cleared to fly.
However, Elwell said Boeing’s MCAS flight control software is “the issue that links these two horrific accidents.”
“We are going to mitigate that,” he said.
Elwell said after the meeting of regulators from 33 nations ended that the gathering had been “comprehensive and constructive.”
“When we broke, there was a great buzz” among the delegates, said Elwell. “I definitely got the impression that what they had heard was extremely helpful to them.
Dominic Gates: 206-464-2963 or [email protected]; on Twitter: @dominicgates.
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Boeing Statement
https://boeing.mediaroom.com/2019-05...lators-Meeting
Boeing Statement on Federal Aviation Administration Global Regulators Meeting
CHICAGO, May 23, 2019 – We appreciate the FAA's leadership in taking this important step in bringing global regulators together to share information and discuss the safe return to service of the 737 MAX. Our team, our airline customers, and regulators place the highest priority on the safety of the flying public. Once we have addressed the information requests from the FAA, we will be ready to schedule a certification test flight and submit final certification documentation.
Contact
Boeing Communications
312-544-2002
[email protected]
CHICAGO, May 23, 2019 – We appreciate the FAA's leadership in taking this important step in bringing global regulators together to share information and discuss the safe return to service of the 737 MAX. Our team, our airline customers, and regulators place the highest priority on the safety of the flying public. Once we have addressed the information requests from the FAA, we will be ready to schedule a certification test flight and submit final certification documentation.
Contact
Boeing Communications
312-544-2002
[email protected]
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If, as it has been said, the force to turn the manual trim wheel (if the MCAS goes amuck) is higher than the crew can overcome, it would seem that the aircraft can not be certified until that problem is solved.
Horizontal Stab tail area
Ref Boeing 737 Detailed Technical Data
This indicates that the horizontal stab tail areas have increased in latter variants of the 737, approx 29 up to 33 sq m.
What effect might this have on the ability to move the stab with the manual trim wheel.
Longtimer, not so much a MCAS issue after modification, but still an important problem for tail trim runaway.
The recent Boeing statement (#98) does not have the same ‘ring’ of confidence (early return to service) that previous statements had.
Possibly a reflection on yesterday’s regulatory meetings.
Elwell confirmed that Boeing’s final application for changes to the MAX’s maneuvering characteristics augmentation system (MCAS) has not been received. Once the package is in FAA’s hands, “we will perform our final risk assessments and analysis, taking into account findings of the [Technical Advisory Board] and any information we receive from our international counterparts
This indicates that the horizontal stab tail areas have increased in latter variants of the 737, approx 29 up to 33 sq m.
What effect might this have on the ability to move the stab with the manual trim wheel.
Longtimer, not so much a MCAS issue after modification, but still an important problem for tail trim runaway.
The recent Boeing statement (#98) does not have the same ‘ring’ of confidence (early return to service) that previous statements had.
Possibly a reflection on yesterday’s regulatory meetings.
Elwell confirmed that Boeing’s final application for changes to the MAX’s maneuvering characteristics augmentation system (MCAS) has not been received. Once the package is in FAA’s hands, “we will perform our final risk assessments and analysis, taking into account findings of the [Technical Advisory Board] and any information we receive from our international counterparts