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-   -   Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed (https://www.pprune.org/rumours-news/618252-boeing-737-max-software-fixes-due-lion-air-crash-delayed.html)

PastTense 11th Feb 2019 04:56

Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed
 

Engineering and regulatory complications are expected to delay safety fixes covering hundreds of Boeing Co. BA -0.06% 737 MAX jets until at least April, according to industry and government officials familiar with the details.Boeing is developing revised software for an automated flight-control feature that can forcefully push down the nose of MAX aircraft and was implicated in a high-profile Lion Air crash in Indonesia this past October. But the work has dragged on months longer than initially anticipated following the accident, these officials said.
In addition to engineering challenges, they said, another reason for the delay stems from differences of opinion among some federal and company safety experts over how extensive the changes should be.Originally, software updates were expected to be fairly straightforward and slated to be announced in early January. But since then, there have been discussions about potentially adding enhanced pilot training and possibly mandatory cockpit alerts to the package, according to one person briefed on the details.There also has been consideration of more-sweeping design changes that would prevent faulty signals from a single sensor from touching off the automated stall-prevention system, officials said. But at this point, they said, such options appear to be losing favor among regulators.The 35-day partial government shutdown—during which consideration of the fixes was suspended—also created further delays.Over the weekend, a Boeing spokesman said the company “continues to evaluate the need for software or other changes as we learn more from the ongoing investigation.” He declined to elaborate on specifics.Since the accident, the Federal Aviation Administration has said it is considering taking action depending on the results of the investigation and reviewing certain issues related to its certification of 737 MAX aircraft.The Oct. 29 crash of Lion Air Flight 610 roughly 11 minutes after takeoff from Jakarta, killing all 189 on board, has raised fundamental questions about the limits and potential downsides of cockpit automation. The tragedy has highlighted the hazards when automated flight-control features fail or misfire, and pilots aren’t able to respond properly. Boeing has faced criticism from some airline officials, aviators and pilot union leaders for omitting details about the new stall-prevention system in the 737 MAX’s manuals or training requirements, which were approved by the FAA.The Chicago-based plane maker has said the process to create its manuals and training for the 737 MAX was consistent with developing previous airplanes, and that it provided information needed to safely fly the airplane. Boeing has said the airplane is safe and noted it is in operation around the world.Boeing favors a relatively simple solution that would primarily reduce the power and, under some circumstances, probably the repetitive nature of the flight-control system in question, called MCAS, according to these government and industry officials tracking the process. That appears to be the most likely outcome, they said, though no final decisions have been made. And the timing for an announcement remains fluid. The FAA is poised to mandate changes to the 737 MAX once there is a company-government consensus about the overall package.The stakes in the current debate go beyond skirmishes over arcane engineering judgments or Boeing’s design philosophy. The upshot, according to some industry officials and outside safety experts, could affect future suits filed by lawyers representing families of victims.The accident probe will take months to complete, as investigators look at factors ranging from maintenance to operations to aircraft design.The Indonesian-led investigation has tentatively concluded that sensor-calibration issues during maintenance touched off the fatal sequence of events, according to people familiar with the process. Investigators also have said the automated flight-control system was central to the crash, and they have publicly identified a number of pilot slip-ups that appear to have played an important part.The stall-prevention system was designed just for the 737 MAX, a variant of Boeing’s workhorse single-aisle jet that Boeing made its debut in 2015. U.S. operators of the new plane include Southwest Airlines Co. , American Airlines Group Inc. and United Continental Holdings Inc.Among measures the FAA has considered was whether to require all 737 MAX airplanes to be outfitted with indicators that alerts pilots when sensors that feed into the stall-prevention system disagree, the officials said. So-called angle of attack sensors essentially reflect the angle of the plane’s nose versus level flight. Cockpit alerts that show when such sensors disagree are currently optional on the fleet.Preliminary data released by Indonesian investigators points to the MCAS feature misfiring when incorrect signals from a single angle-of-attack sensor prompted the system to repeatedly push down the plane’s nose.In the Lion Air crash, investigators have indicated the pilots fought the MCAS system as it strongly and repeatedly pushed down the plane’s nose, but didn’t follow an existing procedure to deactivate it. Indonesian authorities have recovered, and more recently downloaded data from, Lion Air Flight 610’s cockpit-voice recorder. But they haven’t indicated what clues it may provide about the crew’s understanding of the system, and why shortly before the fatal dive the co-pilot apparently eased back on his nose-up commands.On MAX 8 models, under certain conditions, pilots may be unable to pull the plane out of a dive unless they react quickly and proceed to the most relevant portion of their emergency checklist. Outside safety experts have questioned how the FAA gave the green light for such a design lacking redundant software or hardware safeguards. One malfunctioning sensor or a single stream of faulty signals—called a “single point failure” in engineering lingo—can lead to a catastrophic dive, if pilots react improperly.As part of the overall Lion Air probe, the FAA has said its experts are reviewing that and other issues around how the aircraft was certified to fly passengers.

https://www.wsj.com/articles/boeing-...sh-11549821489

DaveReidUK 11th Feb 2019 06:27

Slightly more readable version for anyone who can't get behind the WSJ's paywall:


Engineering and regulatory complications are expected to delay safety fixes covering hundreds of Boeing Co. BA -0.06% 737 MAX jets until at least April, according to industry and government officials familiar with the details.

Boeing is developing revised software for an automated flight-control feature that can forcefully push down the nose of MAX aircraft and was implicated in a high-profile Lion Air crash in Indonesia this past October. But the work has dragged on months longer than initially anticipated following the accident, these officials said.

In addition to engineering challenges, they said, another reason for the delay stems from differences of opinion among some federal and company safety experts over how extensive the changes should be.

Originally, software updates were expected to be fairly straightforward and slated to be announced in early January. But since then, there have been discussions about potentially adding enhanced pilot training and possibly mandatory cockpit alerts to the package, according to one person briefed on the details.

There also has been consideration of more-sweeping design changes that would prevent faulty signals from a single sensor from touching off the automated stall-prevention system, officials said. But at this point, they said, such options appear to be losing favor among regulators.

The 35-day partial government shutdown—during which consideration of the fixes was suspended—also created further delays.

Over the weekend, a Boeing spokesman said the company “continues to evaluate the need for software or other changes as we learn more from the ongoing investigation.” He declined to elaborate on specifics.

Since the accident, the Federal Aviation Administration has said it is considering taking action depending on the results of the investigation and reviewing certain issues related to its certification of 737 MAX aircraft.

The Oct. 29 crash of Lion Air Flight 610 roughly 11 minutes after takeoff from Jakarta, killing all 189 on board, has raised fundamental questions about the limits and potential downsides of cockpit automation. The tragedy has highlighted the hazards when automated flight-control features fail or misfire, and pilots aren’t able to respond properly. Boeing has faced criticism from some airline officials, aviators and pilot union leaders for omitting details about the new stall-prevention system in the 737 MAX’s manuals or training requirements, which were approved by the FAA.

The Chicago-based plane maker has said the process to create its manuals and training for the 737 MAX was consistent with developing previous airplanes, and that it provided information needed to safely fly the airplane. Boeing has said the airplane is safe and noted it is in operation around the world.

Boeing favors a relatively simple solution that would primarily reduce the power and, under some circumstances, probably the repetitive nature of the flight-control system in question, called MCAS, according to these government and industry officials tracking the process. That appears to be the most likely outcome, they said, though no final decisions have been made. And the timing for an announcement remains fluid. The FAA is poised to mandate changes to the 737 MAX once there is a company-government consensus about the overall package.

The stakes in the current debate go beyond skirmishes over arcane engineering judgments or Boeing’s design philosophy. The upshot, according to some industry officials and outside safety experts, could affect future suits filed by lawyers representing families of victims.

The accident probe will take months to complete, as investigators look at factors ranging from maintenance to operations to aircraft design.

The Indonesian-led investigation has tentatively concluded that sensor-calibration issues during maintenance touched off the fatal sequence of events, according to people familiar with the process. Investigators also have said the automated flight-control system was central to the crash, and they have publicly identified a number of pilot slip-ups that appear to have played an important part.

The stall-prevention system was designed just for the 737 MAX, a variant of Boeing’s workhorse single-aisle jet that Boeing made its debut in 2015. U.S. operators of the new plane include Southwest Airlines Co. , American Airlines Group Inc. and United Continental Holdings Inc.

Among measures the FAA has considered was whether to require all 737 MAX airplanes to be outfitted with indicators that alerts pilots when sensors that feed into the stall-prevention system disagree, the officials said. So-called angle of attack sensors essentially reflect the angle of the plane’s nose versus level flight. Cockpit alerts that show when such sensors disagree are currently optional on the fleet.

Preliminary data released by Indonesian investigators points to the MCAS feature misfiring when incorrect signals from a single angle-of-attack sensor prompted the system to repeatedly push down the plane’s nose.

In the Lion Air crash, investigators have indicated the pilots fought the MCAS system as it strongly and repeatedly pushed down the plane’s nose, but didn’t follow an existing procedure to deactivate it. Indonesian authorities have recovered, and more recently downloaded data from, Lion Air Flight 610’s cockpit-voice recorder. But they haven’t indicated what clues it may provide about the crew’s understanding of the system, and why shortly before the fatal dive the co-pilot apparently eased back on his nose-up commands.

On MAX 8 models, under certain conditions, pilots may be unable to pull the plane out of a dive unless they react quickly and proceed to the most relevant portion of their emergency checklist. Outside safety experts have questioned how the FAA gave the green light for such a design lacking redundant software or hardware safeguards. One malfunctioning sensor or a single stream of faulty signals—called a “single point failure” in engineering lingo—can lead to a catastrophic dive, if pilots react improperly.

As part of the overall Lion Air probe, the FAA has said its experts are reviewing that and other issues around how the aircraft was certified to fly passengers.

infrequentflyer789 11th Feb 2019 09:52


Originally Posted by DaveReidUK (Post 10386515)
Slightly more readable version for anyone who can't get behind the WSJ's paywall:

Thanks, much more readable



There also has been consideration of more-sweeping design changes that would prevent faulty signals from a single sensor from touching off the automated stall-prevention system, officials said. But at this point, they said, such options appear to be losing favor among regulators.

Um, really? So that implies B will continue to kick off "automated stall prevention", directly opposing pilot inputs, based on output of a single sensor with no cross checks? :confused:

Pardon the expression, but if not that, WTF are they fixing?

gums 11th Feb 2019 14:01

Salute!

@ infrequent :ok: they are "fixing" to face zillions of $$ in liability lawsuits concerning potentially negligent certification procedures and failure to fully/clearly explain to the crews what the new flight control doofer could do if one AoA sensor or maybe another single component failed.
Gums opines...

RatherBeFlying 11th Feb 2019 15:30

The 747 came out with triple INS. In case of disagreement, the odd one was voted out.

With the criticality of MCAS, it seems a strong candidate for triple sensors and a voting algorithm.

jimtx 11th Feb 2019 15:44

Why not just disable the system on all aircraft? If you do encounter an abnormal where you are down to manual trim the Boeing procedures don't add any caution about avoiding any flight regime that MCAS was supposed to protect.

hans brinker 11th Feb 2019 16:16


Originally Posted by jimtx (Post 10386965)
Why not just disable the system on all aircraft? If you do encounter an abnormal where you are down to manual trim the Boeing procedures don't add any caution about avoiding any flight regime that MCAS was supposed to protect.

https://cimg9.ibsrv.net/gimg/pprune....b62da90118.jpg
https://cimg0.ibsrv.net/gimg/pprune....6092bf2e88.jpg

Because they can't certify the aircraft without MCAS. At high AOA the engines (being MUCH bigger and WAY further forward) provide too much aerodynamic lift ahead of the CG, pushing the nose up even further. MCAS adds AND trim in this scenario. Just compare the B737-100 with the B737-MAX and you see why they needed to add electronic band-aids to keep it legal.

PEI_3721 11th Feb 2019 16:32

jimtex,
the problem is not a simple issue of trimming the aircraft.
Automatic application of trim appears to be used to improve marginal pitch stability in specific areas of the flight envelope. e.g. with high thrust the aircraft might pitch up faster than could be managed with normal stick input, thus nose down trim reduces the flying task and risk of loss of speed.
No MCAS, no certification, #7.

The delay is probably a complex interaction of embarrassments; Boeing certification, FAA oversight, EASA talking away doubts, interpretation of required levels of safety, system probabilities, and any other issue which might have been ‘overlooked’ - signed off under grandfather rights / common type certification and pilot rating. Once you have opened a box of issues then all need reconsideration.

In addition, having opened the electronic ‘box’ containing AoA computation, then what else is in that box which could be, or was affected.
Erroneous low speed awareness, misleading and unwarranted stick shake, feel system, and the difficult question of how much credit should the claimed for pilot intervention in detecting and managing failed systems - particularly where the so called fail-safe system (or process) had failed.

There was a brief discussion on slats in another thread; slats appear to be related to the AoA input in one of the computations. The slats might not have operated, but if the safety integrity of the protection system was lost, then there might be opportunity for an eye watering deployment at high speed.

ImbracableCrunk 11th Feb 2019 16:40


Originally Posted by hans brinker (Post 10386987)
https://cimg9.ibsrv.net/gimg/pprune....b62da90118.jpg
https://cimg0.ibsrv.net/gimg/pprune....6092bf2e88.jpg

Because they can't certify the aircraft without MCAS. At high AOA the engines (being MUCH bigger and WAY further forward) provide too much aerodynamic lift ahead of the CG, pushing the nose up even further. MCAS adds AND trim in this scenario. Just compare the B737-100 with the B737-MAX and you see why they needed to add electronic band-aids to keep it legal.

They should put longer landing gear on the 737 so the engines can be a bit farther back. And maybe change the nose so it's a bit quieter. Maybe put some cutting-edge 1970's avionics in it. How about a more pleasing brown color for the cockpit?

jimtx 11th Feb 2019 16:44


Originally Posted by PEI_3721 (Post 10387003)
jimtex,
the problem is not a simple issue of trimming the aircraft.
Automatic application of trim appears to be used to improve marginal pitch stability in specific areas of the flight envelope. e.g. during go around with high thrust the aircraft might pitch up faster than could be managed with normal stick input, thus ‘prepositioning’ (anticipating) the need for nose down trim reduces the flying task and risk of loss of speed.
No MCAS, no certification, #7.

The delay is probably a complex interaction of embarrassments; Boeing certification, FAA oversight, EASA talking away doubts, interpretation of required levels of safety, system probabilities, and any other issue which might have been ‘overlooked’ - signed off under grandfather rights / common type certification and pilot rating. Once you have opened a box of issues then all need reconsideration.

In addition, having opened the electronic ‘box’ containing AoA computation, then what else is in that box which could be, or was affected.
Erroneous low speed awareness, misleading and unwarranted stick shake, feel system, and the difficult question of how much credit should the claimed for pilot intervention in detecting and managing failed systems - particularly where the so called fail-safe system (or process) had failed.

There was a brief discussion on slats in another thread; slats appear to be related to the AoA input in one of the computations. The slats might not have operated, but if the safety integrity of the protection system was lost, then there might be opportunity for an eye watering deployment at high speed.

IF the go around regime was one of MCAS protected regimes why did Boeing not caution about its loss in the runaway stabilizer procedure either from day 1 of the procedure or when they issued the AD advising that that procedure also will protect against a MCAS malfunction. But MCAS would not be active until flaps were up on a go around. I recall some quotes by some officials that pilots would never see the regime MCAS was designed to protect against. I'm still wondering what GOL told their pilots regarding MCAS.

Smythe 11th Feb 2019 17:17


Why not just disable the system on all aircraft?
Part of the certification was required to provide this software, as the aircraft becomes unstable in certain conditions to to the increased size and weight of the engines.

Smythe 11th Feb 2019 17:18


They should put longer landing gear on the 737 so the engines can be a bit farther back.
They did this on the MAX to use the larger engines

FCeng84 11th Feb 2019 17:29

MCAS is flaps up only. Furthermore, it is not needed to provide anticipatory stabilizer trim in order to maintain sufficient pitch control power via the column/elevator. If column/elevator were not able to generate enough pitch control power without moving the stabilizer other than to provide long term pitch trim that would constitute a certification issue that could not be addressed via either stabilizer trim or a stick pusher.

The certification issue that is addressed by MCAS is that the inherent pitch up encountered at high AOA, aft CG, flaps up is such that increased AOA can require relaxing of the column pull needed to initiate the maneuver. Requirements call for stick force needed to increase AOA up to stick shaker must not drop with increasing AOA.

hans brinker 11th Feb 2019 17:36


Originally Posted by ImbracableCrunk (Post 10387012)
They should put longer landing gear on the 737 so the engines can be a bit farther back. And maybe change the nose so it's a bit quieter. Maybe put some cutting-edge 1970's avionics in it. How about a more pleasing brown color for the cockpit?

Otherwise know as the B757-NG/NEO/MAX

jimtx 11th Feb 2019 17:56


Originally Posted by FCeng84 (Post 10387054)
MCAS is flaps up only. Furthermore, it is not needed to provide anticipatory stabilizer trim in order to maintain sufficient pitch control power via the column/elevator. If column/elevator were not able to generate enough pitch control power without moving the stabilizer other than to provide long term pitch trim that would constitute a certification issue that could not be addressed via either stabilizer trim or a stick pusher.

The certification issue that is addressed by MCAS is that the inherent pitch up encountered at high AOA, aft CG, flaps up is such that increased AOA can require relaxing of the column pull needed to initiate the maneuver. Requirements call for stick force needed to increase AOA up to stick shaker must not drop with increasing AOA.

That would be the stick force felt by a manual handling pilot, right. The autopilot does not care about stick force and will put the attitude where it needs to be regardless. Then again, wouldn't that be how we would hand fly also.

FCeng84 11th Feb 2019 18:27

jimtx - you are right about MCAS addressing a hand flying, handling qualities issue. MCAS is active only when the autopilot is disengaged. You are also correct that a pilot paying close attention to pitch response will manage the stick (or in this case the column on 737) so as to command the pitch attitude needed to achieve the desired normal load factor / flight path angle. The issue here is that certification rules require that increasing pull pitch controller input must be needed to command ever increasing AOA / normal load factor. Without MCAS there are 737MAX flight conditions where AOA / normal load factor can increase with constant column pull such that the pilot would need to relax the pull force in order to avoid exceeding their target nose up pitch maneuver. This characteristic does not comply with certification requirements and thus MCAS was introduced to assure that a steady increase in AOA / normal load factor requires a steady increase in column pull force.

WhatsaLizad? 11th Feb 2019 20:43

So how does this system function during a low level Windshear recovery with the stick shaker activating?

tdracer 11th Feb 2019 21:16

You all appear to missing a very critical portion of the article:

But at this point, they said, such options appear to be losing favor among regulators.
In other words, the FAA/EASA can't agree on what they want.
It's unfortunate and ironic that the more safety critical the change, the more difficult and time consuming it is to get it certified. I ran into this phenomena many times during my career - and that was without the political, lawyer, and ass covering complications that are undoubtedly coming into play on this issue.
-

PAXboy 11th Feb 2019 21:45

Call my cynical ...
  1. Money.
  2. Boeing's reputation for getting it right. [Don't need to spend lots of money checking on them]
  3. Get the new machine into service. [Money]
  4. Lion Air crash [Money]

FCeng84 11th Feb 2019 21:52

WhatsaLizad - Any low level operation would be with flaps extended => MCAS not operable.

tdracer - Agreed, engineers tend to lobby for design features that take their systems from Safe to Safer. Roadblock to enhanced safety are usually found elsewhere.

megan 11th Feb 2019 23:02


The issue here is that certification rules require that increasing pull pitch controller input must be needed to command ever increasing AOA / normal load factor. Without MCAS there are 737MAX flight conditions where AOA / normal load factor can increase with constant column pull such that the pilot would need to relax the pull force in order to avoid exceeding their target nose up pitch maneuver. This characteristic does not comply with certification requirements and thus MCAS was introduced to assure that a steady increase in AOA / normal load factor requires a steady increase in column pull force.
Putting the certification requirement to one side, would a pilot actually have much difficulty with control if the force required decreased with increasing AoA? Any studies ever done with the difficulty it would impose? I'm thinking Airbus where the pilot has no control force feedback.

Roger_Murdock 12th Feb 2019 00:11


Boeing favors a relatively simple solution that would primarily reduce the power and, under some circumstances, probably the repetitive nature of the flight-control system in question, called MCAS
This software change seems to actually be worse than doing nothing. Training is the most important corrective action, followed by better MCAS trigger logic regarding disagreeing AoA.

alexgreyhead 12th Feb 2019 00:23

Am I right in my interpretation that they will still rely on a single AOA sensor?

It would seem logical at first blush that the only sane fix here for such a critical sensor is to add two more AOA sensors and use a voting system (or other way to sanity-check the data) as per the 747's triple INS setup as RatherBeFlying mentioned above?

It seems that any other solution which still relies on one AOA sensor is likely to simply end up a poor-quality patch job, assuming no other sensor input is available that can be relied upon should the sole AOA sensor go faulty.

/Alex - not qualified to talk on this matter at all, so take my post with the bucket of salt it deserves...

averow 12th Feb 2019 00:29

Thank you Gums! If I may be so bold: What was the design philosophy on the F-16 early on? Did it require a "chorus" of sensors to pass data on re AOA, airspeed, etc to render a decision?

As with many complex systems it appears to this observer that "post marketing experience" with the 737 Max has uncovered a design flaw....

gums 12th Feb 2019 01:51

Salute averow
Our AoA data for the FBW system used two conical sensors and one hemisphericl probe that used differentail air pressure for pitch, yaw and total pressure. The pressure probe data was decoded in a special box, and the mechanical AoA values were basically sent to the main FLCS computers ( four of them).

I may have to get with one of the guys over on the F-16.net forums to verify my data, but seems I recall middle value logic until down to two sensor input, then the most benign value.
Our system used only three of the computers until one went tits up, and we brought in the 4th. Looking back, we had a very graceful degradation until all was lost.

Unlike the 737, we depended entirely upon the FBW and associated computers that interpreted our control inputs and then moved the control surfaces. But the 737 was supposed to be aerodynamically a "normal" airplane and not intentionally unstable as was the Viper ( below 0.95M +/-).

It looks to me that the newer variations of the 737 are more like the VooDoo I flew a half century ago. That thing got "light" on the stick when you got close to the critical AoA, and if you kept pulling then the plane increasd AoA all by itself with no stick command or even forward stick. Wahoo!!!

The VooDoo had two AoA and gee limiters depending whether you had the autopilot engaged or not. Also had a stick pusher for rate limiting and actual AoA limits. Worked for me. And all that was back in 1965 or so. Our roll "feel" was only some springs and no change if we were at 300 knots or 700 knots. Pitch was helped by a bellows to account for CAS and a bob-weight to help for our pitch rate commands at higher gee. In short, nothing fancy like we see with the 737 feel system and STS and now the MCAS.

Thanks for the questions...

Gums sends...

4runner 12th Feb 2019 02:00


Originally Posted by ImbracableCrunk (Post 10387012)
They should put longer landing gear on the 737 so the engines can be a bit farther back. And maybe change the nose so it's a bit quieter. Maybe put some cutting-edge 1970's avionics in it. How about a more pleasing brown color for the cockpit?

how about more rubber and bigger brakes so that it doesn’t need more runway than a 767? Oh wait, the gear can’t be longer because that’s where the wheel wells are. Maybe fewer humps in the floor and a JS that isn’t 90 degrees? How about single channel go around too? The 737 is a brand new record player with a digital display.

WhatsaLizad? 12th Feb 2019 02:17


Originally Posted by FCeng84 (Post 10387252)
WhatsaLizad - Any low level operation would be with flaps extended => MCAS not operable.

Thanks, FC. Forgot about that part of the system description, but still might be a concern after going to flaps up at 1000' AGL.


Icarus2001 12th Feb 2019 07:04

https://cimg7.ibsrv.net/gimg/pprune....9e0a495e14.jpg

Rated De 12th Feb 2019 09:17


It's all about bucks, the rest is just conversation -Gordon Gekko
Gordon had it right all those years ago.

ImbracableCrunk 12th Feb 2019 12:16


Originally Posted by hans brinker (Post 10387058)
Otherwise know as the B757-NG/NEO/MAX


Originally Posted by Smythe (Post 10387046)
They did this on the MAX to use the larger engines

Maybe I needed a ;)


Machinbird 12th Feb 2019 13:16

Gums, Betcha forgot about your downsprings on your VooDoo.:8
Other than the pusher, it had a lot in common with the Phantom in its design concept.

Overall, when I look at the design concept for the NG and Max, it seems that the control forces can get awfully high, and when you begin to get into cable stretch force levels, you lose control authority.
As FCEng84 pointed out elsewhere, the elevator is hinge moment limited as to how much deflection it can generate and that too limits a pilot's ability to control his aircraft
I have read that when stall AOA threshold is reached, the control system further increases control forces in order to make it harder to pull further into a stall. How do you spell more loss of control authority?
On the surface, it seems logical, but it all works to take away a pilot's ability to control his aircraft.
Does a transport really have to fly like a truck?

RatherBeFlying 12th Feb 2019 17:00

Time to stop when too many aerodynamic band-aids required
 
It looks like the 37 has finally been stretched [promoted] to its level of incompetence.

Two possible ways out:
  1. Shorten the 87
  2. Use Embraer 195 as a base design.


DaveReidUK 12th Feb 2019 17:18


Originally Posted by RatherBeFlying (Post 10387963)
Use Embraer 195 as a base design.

Hmmm.

To mitigate the 6-abreast 737's inability to be stretched further, you're going to base a replacement on the 4-abreast Embraer?

How exactly is that going to work?

weemonkey 12th Feb 2019 17:37


Originally Posted by WhatsaLizad? (Post 10387362)
Thanks, FC. Forgot about that part of the system description, but still might be a concern after going to flaps up at 1000' AGL.

Hmmm. Does the P8 have this control "assistance" system grafted on/In?

DaveReidUK 12th Feb 2019 17:48


Originally Posted by weemonkey (Post 10387992)
Does the P8 have this control "assistance" system grafted on/In?

Unlikely, given that it first flew 10 years ago and it's based on the NG (737-800), not the Max, so it doesn't have the LEAP engines that have necessitated MCAS.

BluSdUp 12th Feb 2019 22:07

WeeMonkey
 
Pimped up 737-800 , the P8.
It will be interesting to see what they plan to do low level with it.
The power power coupling with rapid pwr changes is nasty if one is used to a P3 I suppose.
The slow trim with flap up is also an issue if yanking and banking at low level. Gets quite heavy.
I know it is supposed to do most of its work from 30 000 feet , but I suspect we will see them at 100 feet up the fjord as well?

weemonkey 12th Feb 2019 22:40


Originally Posted by DaveReidUK (Post 10388005)
Unlikely, given that it first flew 10 years ago and it's based on the NG (737-800), not the Max, so it doesn't have the LEAP engines that have necessitated MCAS.

And none of those aircraft listed have external stores or internal bomb bay.....see where I'm coming from?...what else might MrB been up to in the "hell yeah" department.:}

CONSO 12th Feb 2019 23:08

as I vaguely recall- ONE of the requirements by the navy was low level flight in bad weather on one engine- and was demonstrated with a standard 737 prior to contract award.

and see also
https://www.seattletimes.com/busines...ng-submarines/

Boeing’s P-8 is the 737 with missiles, sonar and a specialty in hunting submarines

737-P8 sub hunter article
https://www.seattletimes.com/busines...ng-submarines/

and post numbers 12 and 13 - answer = 200 feet and maybe even lower


https://www.pprune.org/10138843-post12.html





hans brinker 12th Feb 2019 23:46


Originally Posted by ImbracableCrunk (Post 10387734)
Maybe I needed a ;)

No, I just wish they kept the 757 as opposed to overstretching the 737, 👍

hans brinker 12th Feb 2019 23:49


Originally Posted by Smythe (Post 10387046)
They did this on the MAX to use the larger engines

Well, they had to McGyver an extra hinge/extension thingy in there. There was no room to just put longer legs in there.


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