• Hi Guest! Forum rules have been updated. All users please read here.

Boeing 737 MAX family NEWS ONLY

steelpillow

So many projects, so little time...
Senior Member
Joined
Jun 25, 2014
Messages
754
Reaction score
197
Website
www.steelpillow.com
To be honest, I'd rather see general speculation on future airliner developments being given their own topic elsewhere. This is about the 737 MAX.
The 737 and A320 are inextricably linked, each development in one sparks a development in the other.
Up to a point yes, but dragging in other variants of other models does get a bit off-topic. The MAX futures being verifiably checked out by Boeing, or being equally verifiably laid out for it by the competition, are quite enough here. Sorry, maybe I'm just getting a bit touchy over the various distractions that have happened on this thread in the past.
 
Last edited:

kitnut617

CLEARANCE: Secret
Joined
Dec 15, 2006
Messages
330
Reaction score
38
So is the MAX 9 and MAX 10 the answer for the MAX 8. Drop the MAX 8 entirely and replace with the other two.
 

steelpillow

So many projects, so little time...
Senior Member
Joined
Jun 25, 2014
Messages
754
Reaction score
197
Website
www.steelpillow.com
So is the MAX 9 and MAX 10 the answer for the MAX 8. Drop the MAX 8 entirely and replace with the other two.
The answer to what question? They all have different fuselage lengths with different seating capacities and are consequently optimised for different routes. They all have the high-and-forward engine installations and MCAS.
 

kitnut617

CLEARANCE: Secret
Joined
Dec 15, 2006
Messages
330
Reaction score
38
So is the MAX 9 and MAX 10 the answer for the MAX 8. Drop the MAX 8 entirely and replace with the other two.
The answer to what question? They all have different fuselage lengths with different seating capacities and are consequently optimised for different routes. They all have the high-and-forward engine installations and MCAS.
Well further up the thread it was said that stretching the fuselage would have made the MAX 8's problem much less, even no problem at all (unless I misunderstood what was written). The MAX 9 and 10, being already stretched, seems to me to solve the problem.
 

TomcatViP

Hellcat
Joined
Feb 12, 2017
Messages
1,155
Reaction score
138
The A320 is much slower than any 737. Piloting philosophy is also on opposite worlds. As expressed earlier IMOHO this has helped getting into this disaster with pilot ratings now decorelated with their actual stick time and recorded achievements.

See the "Stuntman" thread* on Tu quo Key Publishing.

*I should rapatriate it here b/w if Mods here and other participants there are willing to agree.
 
Last edited:

Arjen

It's turtles all the way down
Senior Member
Joined
Nov 6, 2010
Messages
2,477
Reaction score
190
Some of those words are English, the sentences are not. Please rephrase.
 

steelpillow

So many projects, so little time...
Senior Member
Joined
Jun 25, 2014
Messages
754
Reaction score
197
Website
www.steelpillow.com
So is the MAX 9 and MAX 10 the answer for the MAX 8. Drop the MAX 8 entirely and replace with the other two.
further up the thread it was said that stretching the fuselage would have made the MAX 8's problem much less, even no problem at all (unless I misunderstood what was written). The MAX 9 and 10, being already stretched, seems to me to solve the problem.
I took a quick look for that comment but couldn't find it again. I think it was based on a misunderstanding of the design principles involved. The pitch sensitivity issue arises from the introduction of the MAX engine/wing arrangement and is common across all models. Fuselage length is irrelevant.
 

kitnut617

CLEARANCE: Secret
Joined
Dec 15, 2006
Messages
330
Reaction score
38
Thanks SP. The comment was something along the lines that the further away the tail plane was, the easier it was to control pitch sensitivity. It just seemed to me that the 9 and 10 covered that ---
 

steelpillow

So many projects, so little time...
Senior Member
Joined
Jun 25, 2014
Messages
754
Reaction score
197
Website
www.steelpillow.com
Thanks SP. The comment was something along the lines that the further away the tail plane was, the easier it was to control pitch sensitivity. It just seemed to me that the 9 and 10 covered that ---
There are key differences between sensitivity, stability, trim and control authority. Yes, in the normal course of events moving the tail back does reduce static sensitivity (i.e. throughout the flight regime). But the MAX engine cowlings introduce a non-linear dynamic destabilisation tendency which only significantly enhances sensitivity at high angles of attack, and this requires a different solution. With both fore and aft aerodynamic surfaces in play, it all gets very complicated.
 
  • Like
Reactions: gTg

DWG

CLEARANCE: Top Secret
Joined
Feb 11, 2007
Messages
537
Reaction score
215
Well further up the thread it was said that stretching the fuselage would have made the MAX 8's problem much less, even no problem at all (unless I misunderstood what was written). The MAX 9 and 10, being already stretched, seems to me to solve the problem.
Do you mean the comment about moving the CofG? Stretches always split the stretch to both sides of the CofG to avoid moving it.
 

kitnut617

CLEARANCE: Secret
Joined
Dec 15, 2006
Messages
330
Reaction score
38
Thanks SP,

DWG, yes I think that was part of it. My comment was why not move the wing forward (my thinking the idea being the tail plane gets moved further away from the CofG but then my thinking was that the CofG gets moved forward too), but then someone said it should go backwards not forwards.
 
Last edited:

TomcatViP

Hellcat
Joined
Feb 12, 2017
Messages
1,155
Reaction score
138
It's more inertia coupling: the mass forward of the rotating axis begining to be favorable to the increase of pitch at high angles of attack (the ones close to stall angle).

Thanks to the geometry of a swept wing that stall at wing tips (washout), once the wing is at near stall angle, the tips are not producing any lift when inboard section are. Look at the geometry of a swept wing and you'll see that all the lift provided by the section close to the fuselage is closer or even forward of the CG. This produces an imbalance that get the plane out of trim, aggravating pilot's inputs at near stall angles.

This is why, ALL swept wing airplane HAVE a level of pitch stability increase, something that will alter the pitch input to give more amplitude to stick travel when the plane reaches those angles. You don't fly without one.

MCAS is just a pitch stability augmentation system that ALSO transposes pitch response to that of earlier series, essentially canceling the diffences in inertia coupling. Just like a digital translator converts good French into good English...
 
Last edited:

DWG

CLEARANCE: Top Secret
Joined
Feb 11, 2007
Messages
537
Reaction score
215

TLDR: FAA estimated one extra Max crash per 2 - 3 years due to MCAS when deciding how to proceed after the Lion Air crash, but decided to let Max continue flying (effectively leading to the Ethiopian crash).

Let's assume 1 extra crash per 2.5 years
c390 Maxs in service at grounding. Production rate of 52 per month. Average number of Maxes in service over next 2.5 years = 390+(2.5*12*52)/2 = c1070
For ROM purposes, let's assume those aircraft fly 12 hours a day, 330 days a year. Over 2.5 years, that's 2.5*330*12 = 9900 hours over the period.
Combining the two to get total Max flight hours per extra hull loss, that's 1070*9900 = 10,593,000, so call it 10.6m flight hours.

Permissible hull loss rate for certification = 1*10^-9 per flight hour, or 1 per 10^9 flight hours.


Dividing the two to get the increase in risk, 10^9/10.6m = 94.3.

So that FAA decision let Max fly with a known issue causing a hull loss rate almost 100 times that permissible for certification.

(NB, I'm just pulling the figures out of the Guardian report, the FAA report released by Congress seems to have calculated risk over the life of the aircraft from the phrasing in the article, so someone has converted that to the 1 per 2 - 3 years figure, and it's not clear if that's FAA, Congress, or the Guardian, the fleet size calculation could be off depending on how they've done this).
 

DWG

CLEARANCE: Top Secret
Joined
Feb 11, 2007
Messages
537
Reaction score
215
Grounding means newly produced airframe can't fly ;)
The FAA was discussing the consequences of _NOT_ grounding MAX, so if those airframes could. Which is precisely what they then did in reality.
 

DWG

CLEARANCE: Top Secret
Joined
Feb 11, 2007
Messages
537
Reaction score
215
But first line of argument is reciprocal:
c390 Maxs in service at grounding.
It's the closest available datum for number in service at the point the decision not to ground was made. In fact it's probably up to 100 aircraft too high, but we'd need a list of individual Max delivery dates and the date the decision not to ground was made to be more precise.
 

TomcatViP

Hellcat
Joined
Feb 12, 2017
Messages
1,155
Reaction score
138
It was such a simple extrapolation. Why didn't you include it in your numbers?
 

steelpillow

So many projects, so little time...
Senior Member
Joined
Jun 25, 2014
Messages
754
Reaction score
197
Website
www.steelpillow.com
The FAA blunder is not the only bombshell in today's hearing. That Guardian report also covers the evidence of an ex-Boeing employee that production was being driven too hard, the shop floor was in chaos and badly-built machines were rolling out the door.
If the global regulators take that last bit on board, they will be demanding detailed inspection and validation of both aircraft and manufacturing records for every single MAX before they let it fly again. The FAA have already determined to do that themselves and no longer take Boeing's word for anything, but most of the fleet is out there around the world, beyond the FAA's reach.
Despite all this, I see elsewhere that Boeing are still taking their sales desk to the aero shows and airlines are still placing orders. However the Guardian's observation that "The 737 Max is the fastest-selling airplane in Boeing history" seems unlikely to be using the correct tense any more.
 

Hood

CLEARANCE: Top Secret
Senior Member
Joined
Sep 6, 2006
Messages
1,459
Reaction score
413
The FOD problems with the KC-46 also don't inspire much confidence in the effectiveness of quality control.
Looking at the 737 in isolation seems folly, what about the rest of the Boeing line-up? If there are build quality issues I can't imagine they would just affect the 737.
 

DWG

CLEARANCE: Top Secret
Joined
Feb 11, 2007
Messages
537
Reaction score
215
It was such a simple extrapolation. Why didn't you include it in your numbers?
Because it would be a finger in the wind guess, and I was trying to give the FAA all the leeway I could. As it is, the fact the figures were for lifetime use and someone else converted them to "2 to 3 years", probably means you can drive a coach and horses through their accuracy. But 15 extra crashes over the life of the fleet is still a huge figure to wave by.
 

DWG

CLEARANCE: Top Secret
Joined
Feb 11, 2007
Messages
537
Reaction score
215

Max return to flight has slipped until at least Mid-February due to outstanding work. I damned near spat my beer over the keyboard when I read 'a combination of factors, including a yet to commence software audit'.

And it's worrying that during the pilot trials, while no one lost the aircraft, fully half the crews initially responded with the wrong procedures. And let's face it, if you're going to be testing as prominent a failure case as this one, you're going to look up all the appropriate procedures in advance, not rely on digging them out of long term storage, so it would probably be worse for unprepared line pilots.

ETA because my concerns over the software audit may not be obvious to people who haven't been through this.

The article says they expect the audit to take 7 days. That's about the time we'd take for a Critical Design Review on an FBW system. That's not sufficient time to dig into the software, it's sufficient time for the auditors to pull a representative handful of Software Change Requests and stand over my shoulder saying "show me exactly where this change is recorded in the change management database", and for me to walk them through it from receipt to design to coding to testing to proving it was in the final software build - but without ever looking at the actual code. There's no way you're doing a detailed code audit in a week, not even if MCAS is a quarter of the size of a full FBW system. The one time we did have a detailed code audit, we had DERA turn up (might have been QINETIQ by then) talk to us for a week, then disappear back to their home base with a copy of the code for several months, and that was code done with Design By Contract, which makes formal proofs a lot simpler, and which Boeing doesn't use.
 
Last edited:

DWG

CLEARANCE: Top Secret
Joined
Feb 11, 2007
Messages
537
Reaction score
215

From mid-November, but has the video and email from FAA head Steve Dickson saying he's got his people's back and they'll certify Max to their schedule not Boeing's. According to the article in the previous post he met with Boeing's CEO Dennis Muilenberg today specifically to address Boeing's 'unrealistic' return to flight schedule.

The comment from the head of Southwest's pilot union in this speculating that Boeing are pushing what they know is an unrealistic schedule in order to push costs onto the airlines is interesting, because it could potentially get Boeing into trouble with the Securities and Exchange Commission, and the SEC are looking at this, as discussed in the link below.

 

steelpillow

So many projects, so little time...
Senior Member
Joined
Jun 25, 2014
Messages
754
Reaction score
197
Website
www.steelpillow.com
Makes you wonder whether the current, i.e. "reshuffled" Boeing management are actually capable of coming clean and rebuilding the trust their company needs. If I were a shareholder, I'd have a scythe and whetstone on my Christmas present list.
 

DWG

CLEARANCE: Top Secret
Joined
Feb 11, 2007
Messages
537
Reaction score
215

'In an email to congressional staff on Thursday disclosing the meeting and seen by Reuters, FAA official Philip Newman said Dickson is “concerned that Boeing continues to pursue a return-to-service schedule that is not realistic due to delays that have accumulated for a variety of reasons. More concerning, the administrator wants to directly address the perception that some of Boeing’s public statements have been designed to force FAA into taking quicker action.” '

That last sentence is not going to go down well the next time Congress grill Muilenburg.
 

galgot

CLEARANCE: Top Secret
Senior Member
Joined
Jul 6, 2006
Messages
625
Reaction score
347
Website
galgot.com
I wonder how much part of why they do that is for pr purpose, while knowing MAX program is in deep s.. And how much part is for really trying to push the FAA .
Or they are out of touch with reality.
 

TomcatViP

Hellcat
Joined
Feb 12, 2017
Messages
1,155
Reaction score
138
Boeing is a profit making organisation like billion other in the world... Yes time and delay matters to them and the pressure build is on the schedule. Hundreds of airframe have been delivered and flown around the world safely. The minimal changes in software are commestical mainly and relate more to the lack of flight worthy personnel (once again MCAS and alike are old as the jet plane).

So posturing indignity doesn't help the case. If that is not most of it.
 

Arjen

It's turtles all the way down
Senior Member
Joined
Nov 6, 2010
Messages
2,477
Reaction score
190
Boeing is a profit making organisation like billion other in the world... Yes time and delay matters to them and the pressure build is on the schedule. Hundreds of airframe have been delivered and flown around the world safely. The minimal changes in software are commestical mainly and relate more to the lack of flight worthy personnel (once again MCAS and alike are old as the jet plane).

So posturing indignity doesn't help the case. If that is not most of it.
Commestical, commestical... ah! Cosmetical! "the lack of flight worthy personnel" - if the pilots are to blame, grounding hundreds of aircraft makes complete sense. Or is that about the airworthiness of pilots floating around the cockpit during a terminal dive?
 

MihoshiK

CLEARANCE: Confidential
Joined
Feb 9, 2007
Messages
128
Reaction score
32
Boeing is a profit making organisation like billion other in the world... Yes time and delay matters to them and the pressure build is on the schedule. Hundreds of airframe have been delivered and flown around the world safely. The minimal changes in software are commestical mainly and relate more to the lack of flight worthy personnel (once again MCAS and alike are old as the jet plane).

So posturing indignity doesn't help the case. If that is not most of it.
Commestical, commestical... ah! Cosmetical! "the lack of flight worthy personnel" - if the pilots are to blame, grounding hundreds of aircraft makes complete sense. Or is that about the airworthiness of pilots floating around the cockpit during a terminal dive?
Well, if you make too many "cosmetical" changes to a piece of software which is expected to drive over a hundered planes into the ground during the MAX expected service life, you have to requalify all pilots. I guess that qualifies as lack of flight worthy personnel.
 

galgot

CLEARANCE: Top Secret
Senior Member
Joined
Jul 6, 2006
Messages
625
Reaction score
347
Website
galgot.com
Well the very existence of the MCAS as to do with without requalifying crews…
So with that logic, "we" can blame the "lack of flight worthy personnel" then.
They were suppose to expect the thing flying like an older 737 version.

Only MCAS still didn’t make the plane fly exactly like the older 737s in certain situations obviously.
 
Last edited by a moderator:

DWG

CLEARANCE: Top Secret
Joined
Feb 11, 2007
Messages
537
Reaction score
215
The minimal changes in software are commestical mainly and relate more to the lack of flight worthy personnel (once again MCAS and alike are old as the jet plane).
There's something incredibly distasteful in continuing to try and divert the blame onto the aircrew when the problems with MCAS leading to both crashes have been documented in detail, when they include safety critical designs with single points of failure, and when FAA were estimating, even before the second crash, that there would be at least 15 more crashes because of MCAS over the life of the aircraft.

I've done this stuff for real. Adding an extra channel of data, combining the two channels of data, deciding how to deal with disagreements, these are not cosmetic changes. They're incredibly complex changes.
 
Last edited:

Jemiba

CLEARANCE: Above Top Secret
Staff member
Top Contributor
Senior Member
Joined
Mar 11, 2006
Messages
8,077
Reaction score
413
The opinion, that the 737MAX accidents weren't caused by design flaws, but by the pilots, principally still
can be regarded as freedom of opinion. And this achievement should be cherished here in this forum, too,
even if it is an opinion, against the prevailing one.
But as those accidents caused many casualties, the theme should therefore be handled with a minimum
of sensitivity. So at least the sources should be mentioned, that support the thesis of the pilot error,
otherwise it's no argument in a discussion, but just kind of rude heckle !
Nevertheless, personal attacks are unacceptable.
Please regard this as a warning to both sides ...
 

TomcatViP

Hellcat
Joined
Feb 12, 2017
Messages
1,155
Reaction score
138
Low Pilot ratings pointed out here by the FAA (25th of November) :


Also the Final JATR document enclosed (see the introduction).

Once again, the specific pilots that day are not singled out as individuals but as a certain type of professional lacking the abilities to cope with a relatively simple problem that generations before them have faced in often more stressful situation (nuclear delivery for exemple).

Training is one of more accute problem as are transport regulating organisations that left basic flight knowledge slip out of qualification requirements.

I will try to add more material latter.
 

Attachments

galgot

CLEARANCE: Top Secret
Senior Member
Joined
Jul 6, 2006
Messages
625
Reaction score
347
Website
galgot.com
Low Pilot ratings pointed out here by the FAA (25th of November) :


Also the Final JATR document enclosed (see the introduction).

Once again, the specific pilots that day are not singled out as individuals but as a certain type of professional lacking the abilities to cope with a relatively simple problem that generations before them have faced in often more stressful situation (nuclear delivery for exemple).

Training is one of more accute problem as are transport regulating organisations that left basic flight knowledge slip out of qualification requirements.

I will try to add more material latter.
Appart from pointing the fact that Lion Air is obviously a sh…ty airline (One that clearly would have been reluctant to have to pay for pilots type requalification, for example...) , where exactly does your link point the pilots lack of professional abilities as being THE CAUSE of Flight 610 crash ?
 
Last edited:

Foo Fighter

I came, I saw, I drank some tea (and had a bun).
Joined
Jul 19, 2016
Messages
1,070
Reaction score
151
Just look through this thread, the FAA allowing Boeing to self certify the aircraft as nothing new here folks and moving to have MCAS not included in pilots manuals etc. Look around you.
 

steelpillow

So many projects, so little time...
Senior Member
Joined
Jun 25, 2014
Messages
754
Reaction score
197
Website
www.steelpillow.com
Boeing and airlines at fault
I have not noticed much criticism of the airlines sticking, only of Boeing and the FAA. Do you have any sources for that?
Just look through this thread, the FAA allowing Boeing to self certify the aircraft as nothing new here folks and moving to have MCAS not included in pilots manuals etc. Look around you.
You misunderstand my question. The FAA is not an airline. I look around and I see no evidence that airlines are to blame. Do you have any?
 

Jemiba

CLEARANCE: Above Top Secret
Staff member
Top Contributor
Senior Member
Joined
Mar 11, 2006
Messages
8,077
Reaction score
413
Ok, this thread in the meantime brought up around a dozen reports. Seems, a standard discussion, with stating sources, without mocking or personal attacks doesn't work here ...
This thread is a "News Only" thread now, with posting news from public sources, but without any comments.
 
Last edited:
Top