MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures
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On the fix, validation of the fix, flight test and cert, who is going to do this? If the fix itself was reported to take 40 hours per ac?. Not certain what the fix entails yet, but most likely a very specialized team to do this. How many teams, and how do they decide where to go first?
The airlines then estimate another 100 to 150 hours of prep time per aircraft for flight?
Then the sim time....(after the fix and after the sims have been updated)
This is gonna take a while.
The airlines then estimate another 100 to 150 hours of prep time per aircraft for flight?
Then the sim time....(after the fix and after the sims have been updated)
This is gonna take a while.
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The 787 didn't take that long, and it was delayed for years..😉
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While the MAX was a knee-jerk reaction to the neo, the NG was a reaction to the 320 in the first place.
At that point Boeing was going for a clean sheet aircraft, then the 320 forced the NG ($2 Billion vs $15 Billion)
If the Cl to NG redesign would have included taller landing gear, we might not be discussing this. The NG was all good, except for engine clearance, that has haunted them, and now...it is a nightmare.
the $2 Billion they saved by not redesigning the landing gear/wingbox was gone in the first 2 weeks of the grounding...great decision.
Still no clean sheet ac.
At that point Boeing was going for a clean sheet aircraft, then the 320 forced the NG ($2 Billion vs $15 Billion)
If the Cl to NG redesign would have included taller landing gear, we might not be discussing this. The NG was all good, except for engine clearance, that has haunted them, and now...it is a nightmare.
the $2 Billion they saved by not redesigning the landing gear/wingbox was gone in the first 2 weeks of the grounding...great decision.
Still no clean sheet ac.
And for the likes of Ryanair and others who's fleets consists entirely og NG it was also good.
Missing some comments around the 797, or NMA, as the heir apparent to the 737.
https://en.wikipedia.org/wiki/Boeing...dsize_Airplane
It is not like Boeing haven't in paralell to the Max developed a modern aircraft in the required size. They where supposed to make a go or no-go decision on it this year.
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It's totally ass-backwards to put feel on the stick by moving a primary control surface. I thought the stick controlled the surface, not the other way round! To my mind if they need constant or increasing pressure on the stick as the aircraft enters a stall then B need to add a servo to the stick, not flap a primary control surface just because they can quickly hack into it's motors etc. It's sticky-tape Engineering..
G
G
Is the Poseidon based on the Max or the -800?
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On the fix, validation of the fix, flight test and cert, who is going to do this? If the fix itself was reported to take 40 hours per ac?. Not certain what the fix entails yet, but most likely a very specialized team to do this. How many teams, and how do they decide where to go first?
The airlines then estimate another 100 to 150 hours of prep time per aircraft for flight?
Then the sim time....(after the fix and after the sims have been updated)
This is gonna take a while.
The airlines then estimate another 100 to 150 hours of prep time per aircraft for flight?
Then the sim time....(after the fix and after the sims have been updated)
This is gonna take a while.
Extract from https://www.latimes.com/business/la-...524-story.html
Southwest, the largest Max operator, is already planning for the plane’s return even though it’s not clear if that is weeks or months away. “It will be a staggered-type return to service,” said Gary Bjarke, director of contract services for the Dallas-based carrier.
Until then, Bjarke leads the team overseeing the upkeep of Southwest’s Max fleet parked on a desert plain in Victorville, Calif., east of Los Angeles. Southwest ferried all its Max planes to the storage yard in the days after U.S. regulators halted commercial flights.
Crews spent about 80 man-hours preparing each jet for storage, and Bjarke estimates it will take about 120 hours of work to get each single-aisle plane back into flying condition. In all, he said, the maintenance checks could take about 30 days before the last of the airline’s parked 737s rejoin daily operations.
Until then, Bjarke leads the team overseeing the upkeep of Southwest’s Max fleet parked on a desert plain in Victorville, Calif., east of Los Angeles. Southwest ferried all its Max planes to the storage yard in the days after U.S. regulators halted commercial flights.
Crews spent about 80 man-hours preparing each jet for storage, and Bjarke estimates it will take about 120 hours of work to get each single-aisle plane back into flying condition. In all, he said, the maintenance checks could take about 30 days before the last of the airline’s parked 737s rejoin daily operations.
Salute!
Thank you, Bum.....
I fully appreciate the effort and $$$ that would have been required to cert the MAX without MCAS. Yep! Maybe it would not be qualified to exploit all the grandfather cert stuff, but the efforrt would certainly have been cheaper than what is now happening, and a lot more safe plane IMHO. Just selling one or two or fifty planes would have paid for all the pain and agony. And a thousand planes on order would now be cranking out. But NOOOOOOO!!!!!!!!!
As far as increased back pressure for increasing AoA, and Bum's comment, it appears the plane already had something in the way of the direct connections to the control surfaces. So all the ropes, cables levers and pulley folks here need to show how "mechanical" the plane is without STS and MCAS and ..... and......
This fixation on training bugs me. I can see it now.
Show up Monday and boss says, "Gums! Get your skinny arse to the sim to see what might happen with this new gizmo on the MAX". "Yessir".
Sim IP says "there is an undocumented feature on the MAX that might crank in unwanted nose down trim, but it's unlikely. Nevertheless, if it goes rogue just after takeoff, you should be prepared". I like that. Be prepared. My Boy Scout exposure and numerous survival schools, altitude chamber rides featuring explosive decompression, some parasailing and practice escaping from under the parachute canopy that came down on top of me, and more.........
"So what do I do?"
"Just fly the plane!"
+++++++++++++++++++++++++++
What about the training scenario for the original design intent? 20,000 feet and holding, then a quick turn. AoA hits the trigger value and I get a bit of nose down trim. Not the big change that the ET and Lion folks saw. And I realize I am pulling back harder that I need to.
Training for the ET and Lion scenarios should be a no-brainer. Stay slow, use manual electric trim, and then turn off the electric trim motor. Oh, wait! Use the wheel doofer on the center pedestal for pitch trim, Gums! No problem. But the nightmare scenario is the birdstrike a few miles on base leg or final and flaps are not down. Ooooppps. AoA gone and MCAS cranks in a gob of nose down trim.
Boeing needs to look at history and the Electra. The Comet episode is another one. Electra showed that it might cost a bit up front, but will pay off down the road. When Electra had the problem, the pure jets were coming along fine and some fans were starting to show up. That is not the case with MAX. So Lockheed moved on and fixed the aero/structural problem. No more big sales except to the ASW community with the P-3. Boeing is not in the same financial or technology environment as Lockheed was back in the 60's. But spending a lotta money up front to satisfy the FAR requirement sure seems cheaper than what is hapening already and what is to come.
Gums opines...
Thank you, Bum.....
It's totally ass-backwards to put feel on the stick by moving a primary control surface. I thought the stick controlled the surface, not the other way round!
As far as increased back pressure for increasing AoA, and Bum's comment, it appears the plane already had something in the way of the direct connections to the control surfaces. So all the ropes, cables levers and pulley folks here need to show how "mechanical" the plane is without STS and MCAS and ..... and......
This fixation on training bugs me. I can see it now.
Show up Monday and boss says, "Gums! Get your skinny arse to the sim to see what might happen with this new gizmo on the MAX". "Yessir".
Sim IP says "there is an undocumented feature on the MAX that might crank in unwanted nose down trim, but it's unlikely. Nevertheless, if it goes rogue just after takeoff, you should be prepared". I like that. Be prepared. My Boy Scout exposure and numerous survival schools, altitude chamber rides featuring explosive decompression, some parasailing and practice escaping from under the parachute canopy that came down on top of me, and more.........
"So what do I do?"
"Just fly the plane!"
+++++++++++++++++++++++++++
What about the training scenario for the original design intent? 20,000 feet and holding, then a quick turn. AoA hits the trigger value and I get a bit of nose down trim. Not the big change that the ET and Lion folks saw. And I realize I am pulling back harder that I need to.
Training for the ET and Lion scenarios should be a no-brainer. Stay slow, use manual electric trim, and then turn off the electric trim motor. Oh, wait! Use the wheel doofer on the center pedestal for pitch trim, Gums! No problem. But the nightmare scenario is the birdstrike a few miles on base leg or final and flaps are not down. Ooooppps. AoA gone and MCAS cranks in a gob of nose down trim.
Boeing needs to look at history and the Electra. The Comet episode is another one. Electra showed that it might cost a bit up front, but will pay off down the road. When Electra had the problem, the pure jets were coming along fine and some fans were starting to show up. That is not the case with MAX. So Lockheed moved on and fixed the aero/structural problem. No more big sales except to the ASW community with the P-3. Boeing is not in the same financial or technology environment as Lockheed was back in the 60's. But spending a lotta money up front to satisfy the FAR requirement sure seems cheaper than what is hapening already and what is to come.
Gums opines...
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Originally Posted by Smythe 
If the fix itself was reported to take 40 hours per ac?.
The airlines then estimate another 100 to 150 hours of prep time per aircraft for flight?
Those numbers are very hard to believe. Where are you getting them from?
If the fix itself was reported to take 40 hours per ac?.
The airlines then estimate another 100 to 150 hours of prep time per aircraft for flight?
Those numbers are very hard to believe. Where are you getting them from?
The airline stated it takes 80 hours to park each ac...so 100 to 150 to bring it out is not unreasonable...again, this is information direct from the airline.
Transit to park, button up the engines, etc...unbutton, required maint, transit....
who knows, it is what American stated in the press..
It's totally ass-backwards to put feel on the stick by moving a primary control surface. I thought the stick controlled the surface, not the other way round! To my mind if they need constant or increasing pressure on the stick as the aircraft enters a stall then B need to add a servo to the stick, not flap a primary control surface just because they can quickly hack into it's motors etc. It's sticky-tape Engineering..
Ooooppps. AoA gone and MCAS cranks in a gob of nose down trim.
BTW, in this sim case, the AOA sensor is out, so you are to manually trim the ac enroute, without an AoA measurement??
So what will the FCOM say, land at the nearest airport?
Last edited by Smythe; 10th Jun 2019 at 23:40.
the AOA sensor is out, so you are to manually trim the ac enroute, without an AoA measurement??
Are you suggesting that one needs an AOA number to trim the aircraft? Or even to fly the aircraft?
Psychophysiological entity
But wait, what actually happened here?
Back in happier times it was deemed necessary to fit the LEAP engines to be competitive. It was also deemed too costly to house longer legs. However, moving the engines forward and up a tad was not all bad, the new thrust didn't have quite the rotation leverage of the NG. Good, but then came the handling on the approach to certain types of stall. Not so good. In fact, the aircraft wasn't certifiable without a fix.
The aircraft already had a black box that 'adjusted' the most powerful control surface on the aircraft. It had worked well for years so why not just write a new algorithm to overcome the light control feel that's a no-no? Seems pretty sensible when you consider what we've just saved - the final sum being part of an Airbus-advantage subduing equation. That is a lot of High-$ reasons to take this course of action. But then somewhere, someone . . . possibly just one person, allows the input from just one AoA vane to be a prime messenger to the system. They, or another someone, deems the g input unnecessary.
Despite there having been a lot of deeming going on, at this point in time it's not as logically bad as one might think. The vane is NOT deemed an item that is in the 'catastrophic' category and so it really wasn't vital to fit a third vane, or even design a comparator circuit to reject unlikely AoA signals and swap to the other one in the blink of an eye. Plenty of data to make a reasonable choice.
In some obscure office, someone deemed the rear Column switch to be in need of rewiring. It's just possible that in the very next office, a person altered the cutout switches on the centre consul. Not one aviation analyst in the world seems to know why they did that.
Nothing in the above is too far removed from things I've read about in the last 55 years. Not that unusual . . . until two vanes fail within a few months because of totally unrelated issues - that is incredibly bad luck, not giving quite enough time to get the significance of a 'Catastrophic' category awarded to those components in time for the second catastrophe.
Strings of events, or holes in cheese, this run of events will change the world's aviation industry forever. You may think it will be like the DC10 or the rudder hard-over issues, but it's so different, in so many ways. There is such a tangled web that it will take not just decades to be 'forgotten', but generations, yet looking at the logic lines, few of them haven't got uncomfortably similar history, it's just the relentless addition of those holes that caused the final disasters.
Back in happier times it was deemed necessary to fit the LEAP engines to be competitive. It was also deemed too costly to house longer legs. However, moving the engines forward and up a tad was not all bad, the new thrust didn't have quite the rotation leverage of the NG. Good, but then came the handling on the approach to certain types of stall. Not so good. In fact, the aircraft wasn't certifiable without a fix.
The aircraft already had a black box that 'adjusted' the most powerful control surface on the aircraft. It had worked well for years so why not just write a new algorithm to overcome the light control feel that's a no-no? Seems pretty sensible when you consider what we've just saved - the final sum being part of an Airbus-advantage subduing equation. That is a lot of High-$ reasons to take this course of action. But then somewhere, someone . . . possibly just one person, allows the input from just one AoA vane to be a prime messenger to the system. They, or another someone, deems the g input unnecessary.
Despite there having been a lot of deeming going on, at this point in time it's not as logically bad as one might think. The vane is NOT deemed an item that is in the 'catastrophic' category and so it really wasn't vital to fit a third vane, or even design a comparator circuit to reject unlikely AoA signals and swap to the other one in the blink of an eye. Plenty of data to make a reasonable choice.
In some obscure office, someone deemed the rear Column switch to be in need of rewiring. It's just possible that in the very next office, a person altered the cutout switches on the centre consul. Not one aviation analyst in the world seems to know why they did that.
Nothing in the above is too far removed from things I've read about in the last 55 years. Not that unusual . . . until two vanes fail within a few months because of totally unrelated issues - that is incredibly bad luck, not giving quite enough time to get the significance of a 'Catastrophic' category awarded to those components in time for the second catastrophe.
Strings of events, or holes in cheese, this run of events will change the world's aviation industry forever. You may think it will be like the DC10 or the rudder hard-over issues, but it's so different, in so many ways. There is such a tangled web that it will take not just decades to be 'forgotten', but generations, yet looking at the logic lines, few of them haven't got uncomfortably similar history, it's just the relentless addition of those holes that caused the final disasters.
Salute!
No need for an AoA indicator to trim. Not even in the shuttle.
Depending on the control laws, electronic or those of actual Sopwith Camels, seems to me that I used the trim to reduce control pressure. Sometimes it was to maintain an attitude, and sometimes to help in a long, hard turn. However, after I got to the fast movers, I had no mechanical connection to the actual control surfaces. So I had no actual "touch" !!! Well, I could still sense burble as I got at high AoA. I could feel gee. So I was not "completely" outta touch. I only used AoA for approaches to validate the rough speed numbers for weight and drag.
=============================
In all fairness to those trying to meet the FAR requirements, those requirements need to be updated. The MCAS kludge was supposed to deal with control pressure versus AoA. But where was that measured? If it was the control stick/column/yoke versus connecting cables, pushrods or hydraulic vales, then what was between them and the surfaces? I cannot find that in the MCAS literature and rationale. OTOH, if the measure of merit was control surface position/ force versus pitch moments, then we might have problems.
The Airbus 320 and following must have a great amount of waivers, exceptions and so forth to gain their certification in the U.S. Unless in the "direct" law, there are many sftwe modules and sensors dictating control surface movement and rate of movement and position. To treat the requirement like a P-51 or Spitfire is not possible. Nevertheless, the plane ( 'bus 320 +) and its family have been certified and have had a really good track record.
Gums sends...
No need for an AoA indicator to trim. Not even in the shuttle.
Depending on the control laws, electronic or those of actual Sopwith Camels, seems to me that I used the trim to reduce control pressure. Sometimes it was to maintain an attitude, and sometimes to help in a long, hard turn. However, after I got to the fast movers, I had no mechanical connection to the actual control surfaces. So I had no actual "touch" !!! Well, I could still sense burble as I got at high AoA. I could feel gee. So I was not "completely" outta touch. I only used AoA for approaches to validate the rough speed numbers for weight and drag.
=============================
In all fairness to those trying to meet the FAR requirements, those requirements need to be updated. The MCAS kludge was supposed to deal with control pressure versus AoA. But where was that measured? If it was the control stick/column/yoke versus connecting cables, pushrods or hydraulic vales, then what was between them and the surfaces? I cannot find that in the MCAS literature and rationale. OTOH, if the measure of merit was control surface position/ force versus pitch moments, then we might have problems.
The Airbus 320 and following must have a great amount of waivers, exceptions and so forth to gain their certification in the U.S. Unless in the "direct" law, there are many sftwe modules and sensors dictating control surface movement and rate of movement and position. To treat the requirement like a P-51 or Spitfire is not possible. Nevertheless, the plane ( 'bus 320 +) and its family have been certified and have had a really good track record.
Gums sends...
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I think the storage thing is getting blown a little out of proportion. It will definitely take time to bring the airplanes back, but I don’t think it is as big a factor as some are making it out. My airline operates one of the larger fleets of the aircraft and they are for the most part getting powered up every few days and engines run a little less frequently but still often. The procedures for long term storage and removal can and are done without a special team from Boeing.
Even the the article quoted said 80 man hours, so a team of 4 takes 2 days to put an airplane back in service. Even the largest max operator with 34, if you get 3 teams going, has all the aircraft back in service in 3 weeks.
Training is going to be the real issue.
Even the the article quoted said 80 man hours, so a team of 4 takes 2 days to put an airplane back in service. Even the largest max operator with 34, if you get 3 teams going, has all the aircraft back in service in 3 weeks.
Training is going to be the real issue.
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I think the storage thing is getting blown a little out of proportion. It will definitely take time to bring the airplanes back, but I don’t think it is as big a factor as some are making it out. My airline operates one of the larger fleets of the aircraft and they are for the most part getting powered up every few days and engines run a little less frequently but still often. The procedures for long term storage and removal can and are done without a special team from Boeing.
Even the the article quoted said 80 man hours, so a team of 4 takes 2 days to put an airplane back in service. Even the largest max operator with 34, if you get 3 teams going, has all the aircraft back in service in 3 weeks.
Training is going to be the real issue.
Even the the article quoted said 80 man hours, so a team of 4 takes 2 days to put an airplane back in service. Even the largest max operator with 34, if you get 3 teams going, has all the aircraft back in service in 3 weeks.
Training is going to be the real issue.
Sorry, we can argue about the significance of the numbers, but let's quote them correctly. "... Bjarke estimates it will take about 120 hours of work to get each single-aisle plane back into flying condition."
If you are relying on control pressure as the input signal into the human, then are you not assuming it is a monotonic function ?
Isn't the point about the increased aero lift off the Max nacelles, that it transforms it into a non-monotonic function ..... ?
Isn't the point about the increased aero lift off the Max nacelles, that it transforms it into a non-monotonic function ..... ?
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Or has this been confirmed somewhere by Boeing or the FAA?
In fact we have just learned that MCAS was originally designed to tackle a problem in high altitude accelerated stall conditions which is something that was not heard of before.
I would be the last to be supprised if the feel issue turns out to be somewhat an understatement.
Sorry for nitpicking, but AFAIK we still have nothing but an educated guess about the nature of the certification issues being just a feel problem.
Or has this been confirmed somewhere by Boeing or the FAA?
In fact we have just learned that MCAS was originally designed to tackle a problem in high altitude accelerated stall conditions which is something that was not heard of before.
I would be the last to be supprised if the feel issue turns out to be somewhat an understatement.
Or has this been confirmed somewhere by Boeing or the FAA?
In fact we have just learned that MCAS was originally designed to tackle a problem in high altitude accelerated stall conditions which is something that was not heard of before.
I would be the last to be supprised if the feel issue turns out to be somewhat an understatement.
However my comment regarding the "no AoA required" is that they are being somewhat simplistic. The FAA requirement is presumably so that the normal pilot in pitch darkness with no external visual references, can still figure out what to do based upon normal behaviours. If however the aero-loads are such that this is a non-monotonic function, and that would appear to be the case for the Max based on the info so far, then those who are saying that an AoA indicator is unnecessary are missing the point in this instance. This FAA requirement is - as far as I can see - intended to give a pilot suitable cues that will not catch them out.