Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed

[tdracer]

Originally Posted by FlightlessParrot

@tdracer: I respect your comments. May I ask if you have any idea why the FAA were slow? It could be that all bureaucrats are incompetent and feckless (a right-wing answer), or it could be that the FAA was under-resourced (a left-wing answer).

I'd say it's quite a bit of both. The FAA - at least the Seattle Area Certification Office (SACO) - was understaffed, both in numbers and in expertise (I say 'was' because I don't have much visibility of what's happened in the 2 1/2 years since I retired, although I have little reason to believe it's changed significantly). Expertise had become a major problem in the last several years before I retired - for a long time most of the SACO people were ex-Boeing and brought their expertise and experience (and many were disgruntled ex-Boeing or otherwise had an axe to grind so it's not like they gave Boeing an easy time of it) - but for various reasons that stopped being the case maybe 15 years ago. Instead they brought in fresh-faced college kids and transfers from other locations that lacked experience in big commercial aircraft. We had one SACO guy working Propulsion who came up from the LA Office - which might have been OK except he'd never worked Propulsion before and had no idea how our systems worked. He was such a nightmare to deal with that his name became almost a swear word among the ARs (delegated DER) - as in when we found he was working your project it was said you'd been Xxxxx'ed (where Xxxxx was his name).
All that being said, a big reasons ex-Boeing people stopped migrating to SACO was because we'd heard what a bureaucratic nightmare the place had become (and was getting worse). I knew two two people that had gone to the FAA from Boeing, only to return to Boeing because they couldn't stand the FAA bureaucracy...

[Fly Aiprt]

Originally Posted by fizz57

The stick force gradient is a certification requirement.

Hi all, new guy here. If stick force is in question, and "no simulator time" now out of the question, why not use a stick pusher to tailor stick forces instead of mistrimming the aircraft ?

[Dogma]

Originally Posted by A0283

You have repeated this statement a number of times.

Certainly not saying you are right or wrong here (that would depend on how you define "FBW" and how you define a "FBW AIRCRAFT"). But we have to note that Boeing uses the term "FBW" in its own documentation for the MAX. And, in his Senate hearing testimony the acting Administrator of the US FAA uses the term "FBW" for the MAX.

There are at least 2 functions and solutions in the MAX that, depending on how you define it, could be ranked under FBW.

If you accept them as such, then we would have to make a distinction between aircraft with one or more 'FBW functions' and 'FBW aircraft'. For some this distinction might not be big, but for others this is big.

For the last group of people, definitions are extremely meaningful and therefore important. If you use another definition then you may be talking about very different 'things'.

For example - one way to look at it is - that the A320 came with a "FBW unless philosophy" (which implies a certain level of "automation", but also added a "glass cockpit" and "sidesticks", and embedded this in the philosophy of "how and where Airbus puts pilots in the loop" (which implies a certain level of "automation").

Between the 'iron' 737 and the 'fbw' 320 there is a large grey area. The 737MAX is somewhere in that grey area. The 2 accidents discussed here indicate to me that we all need clearer definitions. We need them first to understand eachother, and second to get to better solutions.

Good observation. The B737 is becoming a bastardised aircraft with fly by wire patches on a manual aircraft. Any other aircraft have a LAM? Landing Attitude Modifier? It’s fricken Frankenstein..

As a diehard Boeing fan, it’s too depressing

[BluSdUp]

Tdracer

Bureaucracy
Hmm, Is that not part of the problem here TD, The Big Overseer FAA not having the oversight!
" Boys, that looks to satisfy the details, but is it fit for purpose , and is one input smart considering You have two available!!??"

Note
Having English as a second language and being a tad dyslectic I tried to remember how Bureaucracy spells:
Burea U Cracy.

Regards
Cpt B

[GrobDJ]

Two AoA sensors is not the answer, which one is right? Airbus has three and already has one fatal crash where two AoAs were were iced up, and the computer decided they were right and the remaining unfrozen sensor was wrong.

Any sensors in the airstream are exposed to damage, ice etc, no guarantee that a flock of birds should take out just one AoA sensor.

Surely the software should track pitch output from the attitude gyros against AoA, and report any sudden deviation.

[gums]

Salute!

Well, mister 42 and Fizz and others. Thanks for the reminder for those just checking in and those who do noit yet understand the intent and implementation of the MCAS - software and electrical wiring.

How many times must we here and Boeing and FAA and others have to point out [ the purpose of] the MCAS software kludge with its control over a very powerful aerodynamic feature, and then bypassing the older trim stab electrical switches, and then not telling the pilots and then..... GASP!!!

The damned feature was implemented to increase back stick control force at high AoA. PERIOD!! Sure, I don't want the stick getting lighter when I increase AoA close to the stall. But the cert requirement states that the pressure must increase as we get to the stall AoA. Apparently, Boeing couldn't do it aerodynamically without lottsa testing and mods and ...... So we got this half- ice kludge doofer and nobody knew about it.

Gums sends...

[BluSdUp]

Power/Pitch MAX vs -800

Can anyone that has HAND flown the MAX and the 737-800 please tell me if it has the same or less Pitch coupling.
Met a Cpt the other day that claimed it was much easier to fly???
Find this statement strange , now, but specifically DOES IT DROP THE NOSE AS MUCH AS THE -800 on power reduction.
Suspect NOT as the center of thrust is higher.
Anyone
Regards
Cpt B

[b1lanc]

Originally Posted by A0283

You have repeated this statement a number of times.

Actually, I've only said this once that I recall - but age can take its toll. Maybe it's the blue boxes that are confusing you?
But I'll give you my definition of FBW - no cables or pulleys.

[A0283]

b1lanc

Actually, I've only said this once that I recall - but age can take its toll. Maybe it's the blue boxes that are confusing you?
But I'll give you my definition of FBW - no cables or pulleys.

@b1lanc - I deleted that line from my post. There certainly were some blue boxes ;-)
@b1lanc - Thanks for the definition !

[b1lanc]

Originally Posted by A0283

b1lanc

@b1lanc - I deleted that line from my post. There certainly were some blue boxes ;-)
@b1lanc - Thanks for the definition !

Cheers A0283

[42...]

Originally Posted by fizz57

The stick force gradient is a certification requirement.

And Boeing says they didn't need MCAS to pass certification.

[Lost in Saigon]

Originally Posted by 42...

And Boeing says they didn't need MCAS to pass certification.

That is the first time I have heard anyone say that. Do you have a reference?

[WHBM]

One month on, there seems little or no progress. Operators with grounded aircraft don't know where they are or what they should do with their fleets. Little from Boeing and absolutely nothing from the FAA. Production is piling up, presumably of complete aircraft built to the old spec with no AoA disagree warning. Only the Ethiopian authorities seem to have made a major announcement.

Boeing said Tuesday that the company’s internal analysis determined that relying on a single source of data was acceptable and in line with industry standards because pilots would have the ability to counteract an erroneous input.

"Industry standards" ? That's surely incorrect. Multiple source and handling of failures/disagree has been normal in this area since the Trident more than half a century ago incorporated a stick pusher based on similar inputs. Airbus likewise.

[infrequentflyer789]

Originally Posted by Takwis

Agreed. I much prefer the "iron" philosophy to the FBW one, but if you are going to go FBW, you need the redundancy, triple checking, and etc. that go with it. The mix in the MAX is obviously deadly.

Yep, that is the core of the problem - grafting bits of FBW onto a platform that was never designed for it and doesn't have (or really need) the level of redundancy to provide reliable data for FBW. It's not even as if Boeing doesn't know this - they are (or used to be) perfectly capable of building a proper FBW aircraft, they just decided to create a Frankenstein instead.

Only the second mention of LAM that I have seen in all these discussions (the first being mine)...there's another obvious kludge to fix a design error.

Not sure I would bet against it all hanging off of one Rad Alt either...

Interestingly there was a thread on tech-log about LAM around a year ago, started with the now very spooky line:

Consider the following to be some of the interesting stuff that Boeing just does not tell you about much....

Now, you might want to get out your numerology books and probability tables, or your lucky rabbit's foot, before you look at the username that started that thread, a year ago:

Spoiler

 

 

JammedStab

[ATC Watcher]

On the 787 there are also some Boeing designed software moving control surfaces ,( including spoilers I understand), in an autonomous way, and without any indication to the pilot : the famous anti turbulence feature. I wonder on how many sensors this system is relying upon .

[CurtainTwitcher]

Originally Posted by ATC Watcher

On the 787 there are also some Boeing designed software moving control surfaces ,( including spoilers I understand), in an autonomous way, and without any indication to the pilot : the famous anti turbulence feature. I wonder on how many sensors this system is relying upon .

The 787 is a clean sheet design, I would expect it has sufficient redundancy. The issue is that this type of technology is being retrofitted without the required level of redundancy specifically because doing so may have broken the exisiting type rating.

It is not the technology per se, that is the problem but it's inappropriate use. Boeing know how to do redundancy properly, they made a rational business choice not to so, for profit.

[DaveReidUK]

Originally Posted by infrequentflyer789

Not sure I would bet against it all hanging off of one Rad Alt either...

Ten years ago, you would have won your bet:

Boeing Issues Reminder After Netherlands Crash

The Dutch Safety Board today said the altimeter was a factor in the crash that killed nine of the 135 passengers and crew onboard. The Boeing 737-800 plane crashed Feb. 25, within a mile of the runway, while trying to land at Amsterdam's Polderbaan of Schiphol Airport. Another 80 were injured in the accident.

Boeing's reminder applies to all the 737 planes it manufactured, not just the kind involved in the crash.

Events of the flight's final moments became clearer today, with the release of the preliminary accident report.

At 1,950 feet above the ground, the altimeter showed the plane to be at negative-8 feet instead, according to safety board chairman Pieter van Vollenhoven.

As a result, the plane's automatic pilot system responded as though the plane were landing, reducing power the way it would if it were nearing the ground. The crew apparently failed to notice that the airspeed was dropping dramatically, according to the report. The plane's ability to fly continued to deteriorate for more than a minute and a half without the pilots taking action.

[nonsense]

Originally Posted by Arydberg

He wrote a book about a car called " unsafe at any speed" about the corvair. The car was discontinued

I read "Unsafe at any speed" as an undergraduate mechanical engineering student in my late 20s in about 1991. None of my younger colleagues had even heard of it, but more surprisingly very few of the engineers I subsequently worked with in the automotive industry (Australian branchs of two big American companies) had heard of it, and NONE had ever read it!

"Unsafe..." was published in 1965. GM produced the Corvair between 1960 and 1969, though sales dropped off considerably after 1965. Unlike my younger colleagues at university, my contemporaries had owned cars of about this age when we started driving, so I'm not all that surprised to read that "A 1972 safety commission report conducted by Texas A&M University concluded that the 1960–1963 Corvair possessed no greater potential for loss of control than its contemporary competitors in extreme situations." I was driving British and Australian cars of the era, but they were all pretty horrid and would generally bite back at hamfisted drivers.

[GordonR_Cape]

Originally Posted by nonsense

A 1972 safety commission report conducted by Texas A&M University concluded that the 1960–1963 Corvair possessed no greater potential for loss of control than its contemporary competitors in extreme situations."

I admire Ralph Nader for his persistence, but he always reminded me of Don Quixote who was always tilting at windmills, whether real or imaginary.

[JPcont]

Originally Posted by GlobalNav

Is it accurate to say that MCAS is AoA stall prevention at all? How would it prevent a stall at all, in normal, non-malfunctioning conditions? It adds nose down trim, yes, while the A/P is off, but it doesn't really prevent stall, at best it gives the pilot a better trim condition for high AoA, which might enable the pilot to prevent a stall. Just asking. MCAS does not make the 737 impossible to stall.

Of course not, but the functionality seems very “similar” but performance poor. As far as I understand, either Alpha Prot is not legally stall prevention system...

Originally Posted by 42...

MCAS, again, is not a stall prevention device, it is a handling modifier. It makes the nose feel heavier to the pilot. Catastrophically so if activated improperly.

It is or claimed to be needed by Boeing flight engineers to prevent a lighter than desired stick force at higher AOA's.

Boeing has right to call their system as they like. I have been involved in naming game couple of times where the aim has been to avoid potential legal, but highly unlikely responsibilities(, with with really bad worst case scenarios).

But, if you look “the publicly known”, and couple of time proofed functionality, you can decide your self...

The presumption is that the main feedback measurement in AoA (it at least had been said so and speed defines mostly the gain?) => MACS is control law of AoA => stall depends mostly on AoA => it is some kind of stall related control system.

It is true that trimming nose down increases stick force but it is just a side effect. What you measure that is what you control. As simple as that. Of course, you might have complicated soft sensoringing capabilities, but in this case seemingly not, because the stick forces went out of the hands.