Boeing’s Own Test Pilots Lacked Key Details of 737 MAX Flight-Control System

Wall Street Journal ^ | May 3, 2019 | Andrew Tangel and Andy Pasztor

[billorites]

Boeing limited the role of its own pilots in the final stages of developing the 737 MAX flight-control system implicated in two fatal crashes, departing from a longstanding practice of seeking their detailed input, people familiar with the matter said.

As a result, Boeing test pilots and senior pilots involved in the MAX’s development didn’t receive detailed briefings about how fast or steeply the automated system known as MCAS could push down a plane’s nose, these people said. Nor were they informed that the system relied on a single sensor—rather than two—to verify the accuracy of incoming data about the angle of a plane’s nose, they added.

Investigators have linked faulty sensor data to the flight-control system’s misfire, which led to crashes in Indonesia and Ethiopia that took 346 lives. Share Your Thoughts

How involved should pilots be in airplane-engineering decisions? Join the conversation below.

The extent of pilots’ lack of involvement hasn’t been previously reported and could bring fresh scrutiny from investigators and regulators already looking into Boeing’s design and engineering practices. It isn’t clear whether greater pilot participation would have altered the ultimate design of the flight-control system. But the scaling back of pilots’ involvement and their lack of detailed knowledge about the plane’s system add to the list of questions about engineering and design practices facing the Chicago-based aerospace giant.

A Boeing spokesman said test pilots and senior pilots didn’t have less of a role in the design, briefing and testing of the final version of MCAS when compared with counterparts who worked on previous models featuring important new systems.

“Listening to pilots is an important aspect of our work,” the spokesman said. “Their experienced input is front and center in our mind when we develop airplanes. We share a common priority—safety—and we listen to them carefully.”

[Moonman62]

No it wasn’t.

Shouting makes you look crazy.

[FtrPilot]

All...the following link was provided by Yo-Yo in comment 47. It contains a lot of good information. In particular, it describes what MCAS is and what it supposed to do.

www.b737.org.uk/mcas.htm

FTA: "MCAS is a longitudinal stability enhancement. It is not for stall prevention (although indirectly it helps) or to make the MAX handle like the NG (although it does); it was introduced to counteract the non-linear lift generated by the LEAP-1B engine nacelles at high AoA and give a steady increase in stick force as the stall is approached as required by regulation."

FTA: "As the nacelle is ahead of the C of G, this lift causes a slight pitch-up effect (ie a reducing stick force) which could lead the pilot to inadvertently pull the yoke further aft than intended bringing the aircraft closer towards the stall. This abnormal nose-up pitching is not allowable under 14CFR §25.203(a) "Stall characteristics"."

Here's FAR §25.203(a): "(a) It must be possible to produce and to correct roll and yaw by unreversed use of the aileron and rudder controls, up to the time the airplane is stalled. No abnormal nose-up pitching may occur. The longitudinal control force must be positive up to and throughout the stall. In addition, it must be possible to promptly prevent stalling and to recover from a stall by normal use of the controls." For anyone that's interested, here's the link for FAR Part 25. Para §25.173, §25.175 and §25.203 are well worth reading.

FAR Part 25

Here's my interpretation...if anyone disagrees, please feel free to comment.

The 737 Max:

1. Is not longitudinally unstable.

2. Engine nacelles produce lift forward the CG at High AOA. This lift causes a pitch up effect as the aircraft approaches stall due to reducing stick force (in the fighter world, we called this stick force lightening).

3. Would not receive Airworthiness Certification without MCAS as required by FAR §25.203(a)

My conclusion is that using MCAS to correct the stall pitch up effect is perfectly acceptable. However, the original MCAS design is faulty.

Also, Boeing's proposed fix is a bandaid. It disables MCAS whenever AOA gages disagree. So, the FAA would not certify the Max without MCAS and yet Boeing's fix will disable MCAS under certain conditions.

IMHO, the proper fix would include a third AOA sensor so the flight control computer could determine a faulty sensor and lock it out. MCAS always stays on.

Comments please...

[billorites]

I mostly agree.

If one relied only on the popular press you would miss a great deal of the subtlety involved.

Longitudinal stability is not a binary thing. There's a continuum from stable to unstable plus an interaction with maneuverability which effects certification.

AFAIK, all swept wing transport category aircraft require some sort of artificial control augmentation in order to comply with FAR §25.203(a) when operated at high altitude/high velocity conditions.

This is compounded by the financial incentive to move CG aft which saves money, but decreases stability.

[fireman15]

If one relied only on the popular press you would miss a great deal of the subtlety involved.

That is being very polite in my opinion. The popular press has been completely misleading. The vast majority of articles and coverage has been sensationalistic and written and/or conceived by people who have no understanding at all of what is being “reported” on. In other words for the sake of the “narrative” there has been a massive amount of speculation by people who have no idea what they are talking about.

Part of the problem in this discussion is that few people who are not pilots seem to understand what the primary function of stabilizer trim is. Simplistically speaking it's primary use by the pilot is as the “speed control” for the airplane. When you have the stabilizer trim set, the plane will gain altitude when you increase power and lose altitude when you decrease power and your airspeed will remain the same.

In an airliner as opposed to my little general aviation airplanes the load and center of gravity is constantly shifting around as passengers and crew move from the front to the rear of the plane and this affects the center of gravity and the trim of the airplane. Cargo and fuel loads can shift as well, so automatic trim was devised over 60 years ago to reduce the pilots’ workload. Using automatic trim to artificially alter the handling characteristics of the airplane is re-purposing what stabilizer trim was originally intended for and required a redesign of a system that had been working well for about 60 years.

[dfwgator]

An eruption on the scale of a Yellowstone super volcano would be a bit more devastating than some Midwest floods. It would dump ash over a large part of the country, and disrupt worldwide weather patterns for possibly years.

And they're worried about SUVs causing Global Warming.

[TexasGator]

"No it wasn’t. Shouting makes you look crazy."

Yes it was!

[Yo-Yo]

My conclusion is that using MCAS to correct the stall pitch up effect is perfectly acceptable. However, the original MCAS design is faulty.

IMHO, that sentence nails the situation perfectly.

Boeing stated that it didn't highlight MCAS to pilots because it was supposed to be transparent to them, and that the conditions that MCAS would activate would be extremely rare in normal operation.

What Boeing failed to do is to activate cross checking of both AoA sensors on aircraft that did not have the Angle Of Attack display option on the Flight Displays. I read somewhere, (and I don't have the link and don't feel like finding it) that Boeing's engineers were supposed to keep the cross check in the software for all versions, but it inadvertently was dropped on non AoA display versions of the software. THAT is an admission of liability.

For those who fear that Boeing will never recover from this, Boeing has already finished updates on the software, flight tested it, showed it to their major airline customers, and submitted it to the FAA and EASA. They are just waiting certification to resume operation of the MAX.

Boeing estimates that they will have that certification by the end of July or early August.

[TexasGator]

“Cargo and fuel loads can shift as well, so automatic trim was devised over 60 years ago to reduce the pilots’ workload. Using automatic trim to artificially alter the handling characteristics of the airplane is re-purposing what stabilizer trim was originally intended for and required a redesign of a system that had been working well for about 60 years. “

Which? Speed control or pilot assist?

The MCAS does not alter the handling characteristics of the Max.

[MinorityRepublican]

I am stunned the CEO is still the face of Boeing. He should have been pushed out when the second crash showed the MCAS had pointed the plane straight down.

He won't last the year. Watch.

[Capt. Tom]

Thanks for your post.

I see the problem of designing a safe easy to operate aircraft as adding expensive designs-a problem when you are in competition to sell your product, and have competition.(Airbus)

It is competition, not for the safest easiest aircraft regardless of price, but for the least expensive to purchase, more fuel efficient aircraft, that can pass Governmental requirements.
That is understandable since Airlines are in business to make money. Fuel efficiency and cost , and maintenance of aircraft is a big factor.

Looks to me like the Govt. will have to pay more attention to the safety aspects of commercial aircraft that undergo alterations.
It appears to me flying is safe but if you alter a design of an existing aircraft the design should get a very cloes inspection.

It is the old story of "Today's solution is tomorrow's problem - Tom

[billorites]

"you are in competition to sell your product, and have competition.(Airbus)"

Pilots are always cautioned against the perils of get-thereitis; the desire to make the trip, attempt the landing, etc. even when better judgement warns them away.

Management is subject to an analogous threat to good judgement.

[Salgak]

I referring to stuff done by Boeing Corporate, not Boeing Aircraft or BMAC. . .

[logi_cal869]

You’re twisting my words. Boeing is contributing to unsafe air travel by building planes to suit markets which employ poorly-trained and experienced operators. Furthermore, as I asserted prior they delivered a fractured software suite: We now know that the “AOA disagree” alert was not enabled on aircraft lacking a purchased option...a major fu$%up on Boeing’s part for relying upon sensor input from a solitary sensor.

Had they just passed with the BS and told its customers & pilots, “HEY, we got a great new spin on an old plane, but you have to push over while driving out of V1 or in hi-G maneuvers,” all would have been fine.

But oh NO: They deign to install software which presumes pilots are incapable of flying, continuing an industry drive to marginalize pilots and, in fact, make the designers solely responsible for crashes such as the 737MAX x2 and AF447 (among others).

To clarify your own statement, “MCAS was ... put in to keep the POORLY-TRAINED PILOT from taking the plane out of its operating envelope during TAKEOFF.

They ARE driving to autonomous flight; the 737MAX and A330 are just steps on the ladder:
https://www.airbus.com/newsroom/stories/Autonomous-skies.html

[MeganC]

Just my two cents here but the redesign of the 737 with the MAX is so significant that it should not be called a 737 at all because the aircraft has significantly different flight characteristics.

It’s not the same aircraft anymore.

Oh, and I will never board a 737 Max 800.

“If it’s Boeing...I’m taking the train.”

[TexasGator]

“To clarify your own statement, “MCAS was ... put in to keep the POORLY-TRAINED PILOT from taking the plane out of its operating envelope during TAKEOFF.”

1. Shame in you for twisting my post.

2. Your clarification is absolutely false as MCAS is will never activate during takeoff.

[lodi90]

They are trying to manage this as if paying out a couple hundred million in lawsuits and a quick SW update will make all this go away. They broke faith with the FAA and with the flying public. This was not an unpredictable random thing this was ....pick your word...criminal...

---

If it’s Boeing it ain’t going.

[logi_cal869]

Not going to debate you on what I already know as fact.

Aside from the technical crap, the graphic from the black box data serves its purpose. Initial climb (aka climbout is more accurate, but ground-dwellers can hardly differentiate between climbout with retracted flaps and takeoff roll/Vr/V2 with flaps. Bottom line: The flight computer was signalling a stall immediately following rotation (column shaking) and MCAS activated at 2000 feet during climbout to cruise altitude as soon as the flaps were retracted (i.e. during takeoff to the layman). They never had a chance due to lack altitude, lack of experience and, more to the point, lack of training on the systems.

Nitpicking on the terminology doesn't change the fact that a "pilot" has already demonstrated that the plane can be flown in spite of MCAS and a single defective sensor.

[BRL]

Ever heard of squandering one’s inheritance?

[TexasGator]

Lack of altitude? They managed to climb for 2000 to 5000 and fly for several minutes …. till the pilot handed off to the SIC.

[Yo-Yo]

How about we just say a drop dead date of December 31, 2019?

If the planes are back in service by that date I’ll happily pay $100 to FR.

If they aren’t then you pay.

Fair enough? If so, we’re on.

Megan

Saving your pennies, Megan?

https://globalnews.ca/news/5309067/faa-boeing-max-june-sources/