MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures
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Fair point. I misquoted. Argument stands even at 120 hours. I don’t think that will be the bottleneck.
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petit plateau, AoA.
Perhaps a slip, but it’s the parameter ‘AoA’, opposed to an indicator which is important in MCAS.
The certification issue appears to involve stability margin, often simplified to stick force vs speed, providing a cue of speed change at constant trim via change of stick force. Minor discrepancies can be adjusted by non pilot trim change according to speed, creating a false stick force, but maintaining a sufficient cue according to requirement.
However, if the problem involves manoeuvre, ‘g’, at constant speed, i.e. stick force reduction when entering a turn without changing speed, then AoA is an alternative input to command trim which induces stick force (AoA would increase in a level turn). Perhaps used together with Mach for additional non linear high speed induced variation.
A major feedback cue for manoeuvre in manual flight is stick force, but an attitude instrument is required without visual cues. Attempting to fly on an AoA indicator could induce even greater instability, “Attempting to follow AOA or speed indications too closely without stabilizing the airplane in pitch can lead to an oscillatory flight path” (Boeing Aero 10).
Perhaps a slip, but it’s the parameter ‘AoA’, opposed to an indicator which is important in MCAS.
The certification issue appears to involve stability margin, often simplified to stick force vs speed, providing a cue of speed change at constant trim via change of stick force. Minor discrepancies can be adjusted by non pilot trim change according to speed, creating a false stick force, but maintaining a sufficient cue according to requirement.
However, if the problem involves manoeuvre, ‘g’, at constant speed, i.e. stick force reduction when entering a turn without changing speed, then AoA is an alternative input to command trim which induces stick force (AoA would increase in a level turn). Perhaps used together with Mach for additional non linear high speed induced variation.
A major feedback cue for manoeuvre in manual flight is stick force, but an attitude instrument is required without visual cues. Attempting to fly on an AoA indicator could induce even greater instability, “Attempting to follow AOA or speed indications too closely without stabilizing the airplane in pitch can lead to an oscillatory flight path” (Boeing Aero 10).
Paris
Paris Airshow press conferences could be interesting. (1)
MCAS approval before Paris would placate many people, but if other problems prevent return to service, then what can be said … nothing, heroes or zeros - no win.
Anticipating a lengthy delay before return to service would require considerable PR media management. Need to dispel all thoughts about discontinuing the MAX, yet wishing to promote confidence in future products without excluding either option.
How much more might the Max be damaged by a new aircraft launch; what effect of continuing confidence in the Max have on a new product, particularly if unwilling to announce the launch of a new aircraft while the Max is grounded.
The aircraft should be stored elsewhere, but a reluctance to move them as this might be an embarrassing indication of a longer delay.
Will we hear more of the exact problems with MCAS, the rejection of Mod 1, what does Mod 2 consist of, what was the root cause of the erroneous AoA value. Current silence, lack of information, is ‘deafening’, perhaps even more significant than any industry speculation on return to service.
How would rumours of other problems - runaway trim drill be presented; no denial so far might suggest there are problems; or is this an FAA problem - who don’t have to stand up at Paris, but some believe that they should.
Selected audiences, scripted questions and replies, hospitality, champagne (cheap); focus on other products (but not 777x wing). Avoid Pprune and ensure regular web page updates, new news, keep things moving on. https://www.boeing.com/commercial/73...ax-update.page
Oh well back to Boeing defence, space, … or any other distraction.
Airbus, … the industry does not trade safety; what happens to B one-day happens to A another day.
Routine sales announcements, technical advancements, future ideas; lots of champagne (best), corks popping and sound of cash registers.
Could be an interesting week.
1) https://www.flightglobal.com/news/ar...r-show-458252/
MCAS approval before Paris would placate many people, but if other problems prevent return to service, then what can be said … nothing, heroes or zeros - no win.
Anticipating a lengthy delay before return to service would require considerable PR media management. Need to dispel all thoughts about discontinuing the MAX, yet wishing to promote confidence in future products without excluding either option.
How much more might the Max be damaged by a new aircraft launch; what effect of continuing confidence in the Max have on a new product, particularly if unwilling to announce the launch of a new aircraft while the Max is grounded.
The aircraft should be stored elsewhere, but a reluctance to move them as this might be an embarrassing indication of a longer delay.
Will we hear more of the exact problems with MCAS, the rejection of Mod 1, what does Mod 2 consist of, what was the root cause of the erroneous AoA value. Current silence, lack of information, is ‘deafening’, perhaps even more significant than any industry speculation on return to service.
How would rumours of other problems - runaway trim drill be presented; no denial so far might suggest there are problems; or is this an FAA problem - who don’t have to stand up at Paris, but some believe that they should.
Selected audiences, scripted questions and replies, hospitality, champagne (cheap); focus on other products (but not 777x wing). Avoid Pprune and ensure regular web page updates, new news, keep things moving on. https://www.boeing.com/commercial/73...ax-update.page
Oh well back to Boeing defence, space, … or any other distraction.
Airbus, … the industry does not trade safety; what happens to B one-day happens to A another day.
Routine sales announcements, technical advancements, future ideas; lots of champagne (best), corks popping and sound of cash registers.
Could be an interesting week.
1) https://www.flightglobal.com/news/ar...r-show-458252/
https://www.boeing.com/defense/marit...don/index.page
https://www.boeing.com/defense/airbo...g-and-control/
If you are relying on control pressure as the input signal into the human, then are you not assuming it is a monotonic
AoA is not a required input to this process.
I have flown three transport category jets and none indicated AoA to the crew.
The P-8 has a different wing with raked wing tips and weapon stations and a bomb bay. So the fuselage with sliding back door (para jump!) and observation windows is different too from some standard 737-800.
This whole trim/AoA rubbish was started by Smythe. I didn’t want to correct him because he had just agreed with me on another topic.. But it makes you wonder what quals some folk on here have.
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This whole trim/AoA rubbish was started by Smythe. I didn’t want to correct him because he had just agreed with me on another topic.. But it makes you wonder what quals some folk on here have.
My point was that I dont see, with the experience level of many pilots today, them being able to keep the ac in trim enroute without the AP. That is my opinion.
Make more sense now?
Last edited by Smythe; 11th Jun 2019 at 15:11.
Smythe, ‘you don’t need ‘it’
‘It’ being MCAS or AoA?
Without MCAS the Max cannot be certificated, so irrespective of being able to fly an unmodified aircraft (probably most pilots can), this is not a viable option.
Re experience and trim; this is irrelevant to the discussion, and also only opinion.
The problem with “I’m entitled to my opinion” is that, all too often, it’s used to shelter beliefs that should have been abandoned. It becomes shorthand for “I can say or think whatever I like” – and by extension, continuing to argue …
Thus “You are not entitled to your opinion. You are only entitled to what you can argue for.” https://theconversation.com/no-youre...r-opinion-9978
‘It’ being MCAS or AoA?
Without MCAS the Max cannot be certificated, so irrespective of being able to fly an unmodified aircraft (probably most pilots can), this is not a viable option.
Re experience and trim; this is irrelevant to the discussion, and also only opinion.
The problem with “I’m entitled to my opinion” is that, all too often, it’s used to shelter beliefs that should have been abandoned. It becomes shorthand for “I can say or think whatever I like” – and by extension, continuing to argue …
Thus “You are not entitled to your opinion. You are only entitled to what you can argue for.” https://theconversation.com/no-youre...r-opinion-9978
"feel"
"It's totally ass-backwards to put feel on the stick by moving a primary control surface"
Yup, but that was already the methodology used by the B737 for tears for the acceleration phase trim issues, by the Speed Trim System, STS. The concept of the MCAS started off as a variant of the STS which has had half a century of operations. The devil was in the details,
Yup, but that was already the methodology used by the B737 for tears for the acceleration phase trim issues, by the Speed Trim System, STS. The concept of the MCAS started off as a variant of the STS which has had half a century of operations. The devil was in the details,
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Paris (2)
Safetypee :
Not so sure .
Just received the GIFAS list of aircraft hat will be presented at the airshow, both static and flight displays. under the Boeing column it says : to be determined.
There was a rumour of a 787-9 to be arriving Monday and departing Tuesday , but even that is unconfirmed.
So far no Boeing aircraft will be on display next week which would be a first in my memory is correct.
Even the usual QATAR show does not include a Boeing this year ( only Airbus and Gulfstream )
Looks like Boeing is going for the low profile posture and the competition is unlikely to use a hammer on the nails , knowing all too well how wind change in Aviation .
Paris Airshow press conferences could be interesting. (1)
Just received the GIFAS list of aircraft hat will be presented at the airshow, both static and flight displays. under the Boeing column it says : to be determined.
There was a rumour of a 787-9 to be arriving Monday and departing Tuesday , but even that is unconfirmed.
So far no Boeing aircraft will be on display next week which would be a first in my memory is correct.
Even the usual QATAR show does not include a Boeing this year ( only Airbus and Gulfstream )
Looks like Boeing is going for the low profile posture and the competition is unlikely to use a hammer on the nails , knowing all too well how wind change in Aviation .
Safetypee :
Not so sure .
Just received the GIFAS list of aircraft hat will be presented at the airshow, both static and flight displays. under the Boeing column it says : to be determined.
There was a rumour of a 787-9 to be arriving Monday and departing Tuesday , but even that is unconfirmed.
So far no Boeing aircraft will be on display next week which would be a first in my memory is correct.
Even the usual QATAR show does not include a Boeing this year ( only Airbus and Gulfstream )
Looks like Boeing is going for the low profile posture and the competition is unlikely to use a hammer on the nails , knowing all too well how wind change in Aviation .
Not so sure .
Just received the GIFAS list of aircraft hat will be presented at the airshow, both static and flight displays. under the Boeing column it says : to be determined.
There was a rumour of a 787-9 to be arriving Monday and departing Tuesday , but even that is unconfirmed.
So far no Boeing aircraft will be on display next week which would be a first in my memory is correct.
Even the usual QATAR show does not include a Boeing this year ( only Airbus and Gulfstream )
Looks like Boeing is going for the low profile posture and the competition is unlikely to use a hammer on the nails , knowing all too well how wind change in Aviation .
737-800BCF
787-9
plus assorted military and the PAV
https://www.boeing.com/airshows/paris/index.page
You dont NEED it to fly the aircraft, if you have experience. Everyone talks about feeling the pressure and trim. Is that even trained in the sim anymore? look at the troubles many have setting trim in the first place.
My point was that I dont see, with the experience level of many pilots today, them being able to keep the ac in trim enroute without the AP. That is my opinion.
Make more sense now?
My point was that I dont see, with the experience level of many pilots today, them being able to keep the ac in trim enroute without the AP. That is my opinion.
Make more sense now?
You learn to trim from the first time you fly. You trim all aeroplanes of all sizes and speeds. It is basic to manual flying. You trim by feel, because the idea of trimming is to have a neutral feel at all times, so you trim out the load.
However... Fly by wire aircraft and earlier CWS - so called Control Wheel Steering (DC-10 type which operates through the AP) don’t require pilot trim input. There is no load for the pilot to trim out. That means that pilots have literally to make efforts not to want to trim when new on type and have to relearn when flying a traditional type - or CWS is off.
The 737 is not in the above category. In manual flight you trim instinctively as soon as there is any pitch load - except in a turn, when the load is expected.
Does that make more sense now?
Back to subject, hopefully.
Salute!
Well, Bill, in the ‘bus, you trim to get the stick back to neutral and relieve whatever pressure those springs exert. So you are trimming off the load.
in the Viper ( not sure about Raptor or Stubby) there was only an eighth of an inch of movement and the computers used actual stick force for the commands. Was not hard to trim for the gee you felt in your butt! Heh heh. For those lacking “feel” the HUD showed instantaneous gee down to the tenth. Our first impression back in 1979 was the thing was a cross between an Atari game and a 1950’s Link trainer. But make no mistake, we trimmed and we trimmed as folks have since the Red Baron days.
+++++++++++++++++++++++++
My contacts in the ‘bus and Viper community claim that switching back and forth is a piece of cake, with the ‘bus not needing much trim at all, but no problem with a stick not mechanically connected to the elevator
I still want someone to explain how Airbus gets certed without any “increase in force with increase in AoA”, huh? Is it because the Boeing still has a mechanical connection to the elevator?
Gums sends....
Well, Bill, in the ‘bus, you trim to get the stick back to neutral and relieve whatever pressure those springs exert. So you are trimming off the load.
in the Viper ( not sure about Raptor or Stubby) there was only an eighth of an inch of movement and the computers used actual stick force for the commands. Was not hard to trim for the gee you felt in your butt! Heh heh. For those lacking “feel” the HUD showed instantaneous gee down to the tenth. Our first impression back in 1979 was the thing was a cross between an Atari game and a 1950’s Link trainer. But make no mistake, we trimmed and we trimmed as folks have since the Red Baron days.
+++++++++++++++++++++++++
My contacts in the ‘bus and Viper community claim that switching back and forth is a piece of cake, with the ‘bus not needing much trim at all, but no problem with a stick not mechanically connected to the elevator
I still want someone to explain how Airbus gets certed without any “increase in force with increase in AoA”, huh? Is it because the Boeing still has a mechanical connection to the elevator?
Gums sends....
Gums what do you mean by trim to get the stick back to neutral on the Airbus? I am having problems understanding what pilot input you are describing. When I flew it you just let go and it returned to neutral.
Only half a speed-brake
Same. gums your derived knowledge of the bus is downright impressive, but things are getting lost in translation at this moment.
Bus, in the normal law (with auto-trim available), needs no active trim input. You pull on the stick, which is spring-loaded (the greater the tilt angle the greater the wrist-force), and an accelerated "G" load pitch-up results. Assuming constant thrust, once established at the desired pitch (and lower speed) you release. The thing trims itself to a steady trajectory, which you had just commanded.
In the downgraded DCT LAW, when control surfaces movements are proportional to stick displacement, she flies exactly like a conventional aeroplane. To reach an in-trim, higher pitch + lower speed condition. a manual input on the pitch-trim wheel is required. The massive difference compared to 737-500/400 (no experience with NG) is that equivalent of classic's one full spin is about half an inch on the bus. Maybe that's where the comment of your friends comes from. You do not grab the wheel, you place the hand on it, palm down. http://www.avioesemusicas.com/wp-con...013/03/THS.jpg
I am not sure which of the two conditions you are referring to. Let's clarify that first, before talking about the "feel resistance approaching stall " / certification.
Bus, in the normal law (with auto-trim available), needs no active trim input. You pull on the stick, which is spring-loaded (the greater the tilt angle the greater the wrist-force), and an accelerated "G" load pitch-up results. Assuming constant thrust, once established at the desired pitch (and lower speed) you release. The thing trims itself to a steady trajectory, which you had just commanded.
In the downgraded DCT LAW, when control surfaces movements are proportional to stick displacement, she flies exactly like a conventional aeroplane. To reach an in-trim, higher pitch + lower speed condition. a manual input on the pitch-trim wheel is required. The massive difference compared to 737-500/400 (no experience with NG) is that equivalent of classic's one full spin is about half an inch on the bus. Maybe that's where the comment of your friends comes from. You do not grab the wheel, you place the hand on it, palm down. http://www.avioesemusicas.com/wp-con...013/03/THS.jpg
I am not sure which of the two conditions you are referring to. Let's clarify that first, before talking about the "feel resistance approaching stall " / certification.
Last edited by FlightDetent; 11th Jun 2019 at 19:16.
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Hi Smythe,
You learn to trim from the first time you fly. You trim all aeroplanes of all sizes and speeds. It is basic to manual flying. You trim by feel, because the idea of trimming is to have a neutral feel at all times, so you trim out the load.
However... Fly by wire aircraft and earlier CWS - so called Control Wheel Steering (DC-10 type which operates through the AP) don’t require pilot trim input. There is no load for the pilot to trim out. That means that pilots have literally to make efforts not to want to trim when new on type and have to relearn when flying a traditional type - or CWS is off.
The 737 is not in the above category. In manual flight you trim instinctively as soon as there is any pitch load - except in a turn, when the load is expected.
Does that make more sense now?
Back to subject, hopefully.
