737 Max

[rob Lyttle]

Looks like Boeing has a major crisis on it's hands. 

Crisis of confidence at least, and that is of paramount importance for an Airliner. 

I have no expertise or insight into the situation. All I can see is the news. 

 

But I wouldn't fancy riding in one right now. 

 

What I'm hearing, and it may be a distortion by the media.... (shock, horror... distortion of the facts? No)

... Is that onboard software can take control, OVERRIDING THE PILOT, in some kind of anti-stall scenario. 

 

There's a lot of loose talk about Red Lines these days in all sorts of areas, but that must surely be a Red Line, and it's been crossed. 

 

I know the pilot only has a plastic joystick anyway, providing inputs for the onboard computer systems, and that's been so for some time now. 

But this is the first time I have heard it described as pushing in front of the pilots and wresting control of the aircraft from them. 

If that is the case, it's not an engineering or aviation decision... It's a moral decision, and it brings us right up to the interface between humans and A. I. 

 

Any body got concerns, insight or information on how deep the problem goes? 

I know pilots can screw up, but having an erroneous control system built into , and in primary control of  the plane is a whole other situation 

[bzn20]

Heres the BBC news page on it

https://www.bbc.co.uk/news/business-47562727

 

Extract from that article by 737 MAX Pilots

The feature, which was new to the 737 Max family, is designed to keep the plane from stalling.

The system prevents the aircraft from pointing upwards at too high an angle, where it could lose its lift.

However, according to filings with the US Aviation Safety Reporting System, which pilots use to disclose information anonymously, it appeared to force the nose down.

In both cases, pilots were forced to intervene to stop the plane from descending.

 

Another  quote from that page

 

After the Lion Air crash, Boeing issued a bulletin on what to do regarding erroneous readings from the sensor, which sends out information about what angle a plane is flying at.

But another pilot said that "it did nothing" to address the problems with the sensor.

They added: "I am left to wonder: what else don't I know? The flight manual is inadequate and almost criminally insufficient."

Doesn't sound like they have much confidence in the 737 MAX .

 

They have the 2 black boxes  and all 371 of them are grounded now .

 

 

 

[Corsairfoxfouruncle]

Its a software issue, the pilots of western airlines are trained to compensate for the anti-stall. But the two crashes have occurred in airlines where the training regimen isnt the same. With the Ethiopean airways crash the pilot had something like 6000 hours on airliners, the copilot had 200.

    The 737 Max has a higher angle of attack on takeoff and the anti stall software is there to keep it in the proper climb attitude. An inexperienced pilot with this system wants to instinctively push forward to prevent stall. When this happens the software pushes back and brings the plane back into a nose high attitude. This causes a porpoising. From what i understand from all the commentary i have seen & read Is eventually the software forces the plane to a level off and trigger an alarm to land as it think there is a system malfunction. I understand that when this happened the pilots were forcing the stick forward and all of a sudden the plane does the same thing. Now they're in a forced dive and cant pull up in time. 

Edited March 13, 2019 by Corsairfoxfouruncle

[bentwaters81tfw]

Apparently the MAX has new, heavier engines, which has altered the CG. The new software, coupled with a new sensor, is designed to compensate. It has been suggested that possibly some pilots have many hours on the earlier models, and try to fly the MAX the same way, and this has caused the problems.

[bzn20]

1 hour ago, Corsairfoxfouruncle said:

This causes a waffling

I've heard a lot of waffling but not waffling in a flying attitude description . What is it like ? Porpoising ?

Edited March 13, 2019 by bzn20

[Corsairfoxfouruncle]

11 minutes ago, bzn20 said:

I've heard a lot of waffling but not waffling in a flying attitude description . What is it like ? Porpoising ?

Excuse the incorrect terminology, yes porpoising. I was typing fast and my mind grabbed the wrong terminology. 

[bzn20]

 

8 minutes ago, Corsairfoxfouruncle said:

wrong

Great term though... Another one for A C Kermode's Mechanics of Flight bible !

 

[hovis]

This won't have any bearing on the Poseidon will it?

[Paul Bradley]

I'm at PHX SkyHarbor at the moment. On the drive in, I noticed 4 Southwest Max lined up on the other side of the airport. 

[Corsairfoxfouruncle]

24 minutes ago, Paul Bradley said:

I'm at PHX SkyHarbor at the moment. On the drive in, I noticed 4 Southwest Max lined up on the other side of the airport. 

Not sure if you’ve heard but the U.S. and Canadian inspectors sent to Ethiopia found something today. The president decided until they can determine what exactly is at fault with the aircraft. All air carriers are to ground all 737 Max 8’s and Max 9’s in U.S. airspace until further notice.  

Edited March 14, 2019 by Corsairfoxfouruncle

[Jamie @ Sovereign Hobbies]

"LEAP-1B,
Due to different engine position (more forward) and nacelle shape of the LEAP engines the manoeuvring characteristics of 737 MAX have slightly changed, causing upward pitching moment. It became necessary to install MCAS (Maneuvering Characteristics Augmentation System) to compensate for this unique handling characteristics as part of the certification process.

MCAS is a function of FCC (Flight Control Computer) and takes Angle of Attack (AOA) data from on-side AOA vane

MCAS activates automatically when all of the following conditions are met:
👉 High angle of attack
👉 Autopilot disengaged
👉 Flaps are up

When the MCAS is active it trims nose down for up to 10 seconds.

Trimming nose up while the MCAS is active will pause the automatic MCAS nose down trim for up to 5 seconds. MCAS will restart nose down trim if the activation criteria are still met.

MCAS trims 0.27 units per second - up to 2.5 units in 10 second cycle

Erroneous high AOA data might cause un-commanded nose down trim through MCAS

MCAS can be disabled and automatic nose down trimming stopped by switching the Stabilizer Trim Cutout Switches to CUTOUT."

 

 

https://www.facebook.com/988569081212364/posts/2113493668719894/

 

 

I hear that there have already been runaway pitch trim events reported and that, in some places at least, this has been acknowledged and crews trained to recognise an uncommanded runaway trim and how to intervene and stop it.

 

Boeing has not accepted there is anything fundamentally wrong with an aircraft with a nasty stall characteristic that requires software to keep pilots away from that edge of the flight envelope, but are actively working on a software modification "to make an already safe aircraft even safer".

[Biggles87]

Anyone remember the early software problems with the Airbus A320?

Apparently the phrase " What's it doing now? " was often heard on flight decks.

 

John

Edited March 14, 2019 by Biggles87

[GrahamS]

32 minutes ago, Biggles87 said:

 " What's it doing now? "

 

John

I bet that’s not the full sentence.

 

Graham

[bhouse]

9 hours ago, bentwaters81tfw said:

the MAX has new, heavier engines, which has altered the CG.

Not only heavier, but mounted higher and further forward. This not only changes the CofG, but also the thrust line and the rotational inertia around the lateral axis. All of these combine to give very different stall/recovery behaviour. 

The problem is that the automatic system designed to deal with the effects was not covered in the training materials used to convert pilots to the type.

[Britman]

3 hours ago, bhouse said:

Not only heavier, but mounted higher and further forward. This not only changes the CofG, but also the thrust line and the rotational inertia around the lateral axis. All of these combine to give very different stall/recovery behaviour. 

The problem is that the automatic system designed to deal with the effects was not covered in the training materials used to convert pilots to the type.

If your last sentence is correct,and I suspect you talk with knowledge of of this, I wouldn't be suprised at a legal claim for negligence.

 

Keith

[Agent K]

15 hours ago, rob Lyttle said:

 

 

I know the pilot only has a plastic joystick anyway, providing inputs for the onboard computer systems, and that's been so for some time now. 

 

Just to be clear, the above is incorrect, unlike the A320 family which is fully FBW with sidestick, the 737 MAX is still conventional/mechanical control and does not have full FBW.

[bhouse]

40 minutes ago, Britman said:

If your last sentence is correct,and I suspect you talk with knowledge of of this

Just to be clear, I have no first hand knowledge of this but have talked to several 737 pilots and seen many online comments about the Max training - this article is typical.

[Jure Miljevic]

Hello

rob Lyttle, I believe aircraft software overriding pilot's command is some thirty years old (first installed on A320), and mechanical overriding devices like stick pusher are around for even longer. Of course, that does not make airliner catastrophes due to sensor, hardware or software error (or due to any other reason, for that matter) acceptable.

Personally I tend to agree with Jamie. While I have no doubts B737 MAX software error fix is going to appear soon, this does not sound like a long term solution. Basic B737 structure has been around for more than fifty years (even longer, if we take into account that her original fuselage was shortened B707 one) and no aircraft can be stretched, re-engined, re-stretched, re-re-engined and so on ad infinitum. Cheers

Jure

[rob Lyttle]

1 hour ago, Jure Miljevic said:

While I have no doubts B737 MAX software error fix is going to appear soon, this does not sound like a long term solution

 

So, that might work OK, (but it sounds like they are juggling too many compromises in the design and hanging it all together with a control system.)

 

The  coming challenge for these guys is, how to win the public and Airlines confidence back .

It can be done. The DC10 had a bit of a dodgy start, if I remember, but made good eventually. 

Recovered back to where it should have been?? 

Hmmm... Maybe not? 

That's going to be a long road. 

[Corsairfoxfouruncle]

9 hours ago, Biggles87 said:

Anyone remember the early software problems with the Airbus A320?

Apparently the phrase " What's it doing now? " was often heard on flight decks.

 

John

Yes remember that well. 

[Jure Miljevic]

Precisely, rob Lyttle. Regarding another question from your first post; do you think A. I. is already too advanced for introduction of Isaac Asimov three laws of robotics into software? Cheers

Jure

[bzn20]

On ‎3‎/‎14‎/‎2019 at 2:44 PM, rob Lyttle said:

DC10 had a bit of a dodgy start

It did have 2 groundings but for different reasons 1st was rear Freight bay door opening in flight on an American Airlines jet , a MOD was issued and supposed to be carried out  on the production line and in service frames but the Turkish jet that crashed near Paris was on the production line and hadn't had the MOD (human error) The second grounding was for the engine mount pins  . That was found to be bad practices ,not IAW the DC-10 Maintenance Manual but fitting the engines in the hangar in service ,which is human error . That was lifting the engine with a forklift putting one pin in and the engine was hanging by one pin and then forked up to locate the second pin which overloaded the first pin , taking the whole engine weight .

 

 

Edited March 16, 2019 by bzn20

[bzn20]

4 hours ago, Jure Miljevic said:

shortened B707 one

Same width across the floor totally different below floor. It's basically a 737 by number with new wings, engines ,avionics , materials and that's the 3rd Gen 737

The MAX is another thing on from the previous, Fin and Tailplane ,so many changes from the 1965 version ,all it can be said is Boeing badges and windows are what's left on the MAX

[Britman]

Triggers broom?

 

Keith

[Stu_davros]

13 minutes ago, Britman said:

Triggers broom?

 

Keith

The modified airframe does not require a brand new type certificate, most aircraft types evolve like this over time.