Ethiopian Airlines Crash/ B737MAX grounding

CoisFharraige

Henry Ford III wrote: »

Out of balance? What does that mean exactly? Are you suggesting the centre of gravity is too far back causing the nose to point up?

When power is applied to any aircraft, it will naturally raise the nose. In training in a 738 (I’d imagine most aircraft) they teach you to let the thrust adjust the attitude on approach.

In the MAX, since the engines are higher up, bigger, and further forward along the fuselage, this increase in power from the engines creates a strong tendency to pitch nose up more so than many other aircraft of its size. This could cause the aircraft to pitch up too dramatically and induce a stall, so MCAS was brought in to counteract this.

Thirdfox

https://www.vox.com/business-and-finance/2019/3/29/18281270/737-max-faa-scandal-explained

Vox gave a good explanation of the "inherent" problems of the Max - competing against the A320neo's large engines in a plane that has wings too close to the ground to mount larger engines.

But I'm not an aviation engineer or pilot - just someone interested in what's going on.

smurfjed

Excellent article, thanks for sharing.

I love the quote in it, Bottom line don’t blame software that’s the band aid for many other engineering and economic forces in effect.

deandean

Jeff2 wrote: »

The only reason the plane needs the system is because of disign fault.

The plane is out of balance and they use a computer and sensors to rectify this rather than developing a new plane that would need to pass all the test.
This was just a cheap way to get around regulations.

But there are loads of planes - i.e. warplanes - that are so inherently unstable that they are practically impossible to fly manually. The flight control software has a huge input into what the control surfaces do.
So I wouldn't be too worried about software that modifies the pilot input so as to better fly the aircraft. As long as it works, of course!

banie01

deandean wrote: »

But there are loads of planes - i.e. warplanes - that are so inherently unstable that they are practically impossible to fly manually. The flight control software has a huge input into what the control surfaces do.

Thats a very false equivalence.

Warplanes use inherent relaxed stability as an aid to instantaneous manuevurability.
High speed reaction to control input is a definite advantage when in a dog fight or avoiding a missile.

The same control response is not warranted in a passenger aircraft.
IMO centres of lift and thrust being at or near equlibrium in a passenger aircraft allows for predictable and gentle control inputs.
Comfort and safety. A fighter will pull 9G in a turn! Anything approaching detectable G impact in a passenger cabin is either extreme turbulence or a sign of departure from a normal flight envelope.

There is nothing wrong with Fly By Wire, but don't equate fly by wire with a software driven flight envelope compensation system.
The plane itself is certified to fly "as" a 738....
It clearly doesn't and the effort to save money on training and certification seems to be inherently and dangerously flawed.

They could take the F4 approach and actually change flight surfaces with a bit of anhedral here, dihedral there, some weight shift to change COG.
But added weight, added drag, added cost all impact the bottom line that made the software fix an attractive option in the 1st place.

The Aircraft was designed to be competitive on a cost per seat basis with the NEO's.
As cheaply as possible. It has come back to bite Boeing on the arse badly!

basill

In a fighter jet when it goes t*ts up the pilot will if at all possible attempt to point it away from civilisation and then bail out.

Irish Steve

deandean wrote: »

But there are loads of planes - i.e. warplanes - that are so inherently unstable that they are practically impossible to fly manually. The flight control software has a huge input into what the control surfaces do.
So I wouldn't be too worried about software that modifies the pilot input so as to better fly the aircraft. As long as it works, of course!

And the very big difference is that warplanes tend to be flown by a pilot, sometimes with other crew members, but if things go badly wrong, they usually have an ejection seat that gives them a much better chance of survival.

That option is not available for 200 + people in a commercial aircraft, so let's not go down that road.

The critical aspect of any assistance device is that it has to be fail safe, so that in the event of a failure, it is still possible to retain control, albeit with some problems, and continue and make a safe landing.

For reasons that have yet to be explained fully, that appears to not be the case with the 737Max and MCAS, hence the worldwide grounding until the issues have been resolved, and proved to be resolved.

MoeJay

I get the impression that MCAS is highly critical to the certification requirements of the aircraft (otherwise why not just deactivate..?).

It could be such that at the end of this process that it is decided that this is the factor that pushes the MAX into a separate type rating from the other 737 aircraft (purely from a licensing perspective, I can't speak for type certs issued by the regulators).

What in effect was a cost saving exercise is going to be a very expensive face saving exercise... Manufacturers, regulators and airlines will all be attempting to point the finger elsewhere!

billy few mates

If this was a brand new aircraft design, nothing to do with the existing 737 the flight characteristics would be totally acceptable.
The problem is that the additional software/features that were added to make it appear identical in handling and flight characteristics to the existing 737 models has proven to be badly designed and implemented. All aircraft have different handling characteristics, crews train for this and become familiar with them and after a while the feel of a particular type becomes totally natural to them.

Pronto63

Bob24 wrote: »

Am i right that there wouldn’t have been any alternative option for airlines and customers then? (as the A320 would be today)

There was actually a greater choice back then for airlines:
McDonnell Douglas and Lockheed in the US alone both with various models.
Hawker Siddeley Trident, Vickers VC10 and BAC 111 from UK
Caravelle from France (pre Airbus days)

These are just the "western" jets that just spring to mind. There would also have been types available from the USSR and China.

Bob24

Pronto63 wrote: »

There was actually a greater choice back then for airlines:
McDonnell Douglas and Lockheed in the US alone both with various models.
Hawker Siddeley Trident, Vickers VC10 and BAC 111 from UK
Caravelle from France (pre Airbus days)

These are just the "western" jets that just spring to mind. There would also have been types available from the USSR and China.

Would those match the 727 both in terms of range and capacity though? (genuine question to which I don’t know the answer, but for the airplanes i know amongst those you quoted I am under the impression they are smaller)

cnocbui

Slightly OT, but astonishing to think that the 1962 Vickers VC10 still holds the Atlantic sub-sonic crossing record. I have actually flown on one.

Pronto63

Bob24 wrote: »

Would those match the 727 both in terms of range and capacity though? (genuine question to which I don’t know the answer, but for the airplanes i know amongst those you quoted I am under the impression they are smaller)

I think they would've been similar.

Just looked up the HS Trident which over the years and various models went from 101 pax to 180 pax and the range went from 1,300 miles to 2,200 miles.

I think the 727 was about 150 pax - not sure of its range.

banie01

cnocbui wrote: »

Slightly OT, but astonishing to think that the 1962 Vickers VC10 still holds the Atlantic sub-sonic crossing record. I have actually flown on one.

I didn't know that!
it is an exceptionally clean aerodynamic plane and it is one of those aircraft that I think proves the maxim "if it looks right, it will fly right"

Hotblack Desiato

billy few mates wrote: »

If this was a brand new aircraft design, nothing to do with the existing 737 the flight characteristics would be totally acceptable.

Not according to these guys.

http://www.b737.org.uk/mcas.htm

This new location and size of the nacelle cause the vortex flow off the nacelle body to produce lift at high AoA; as the nacelle is ahead of the CofG this lift causes a slight pitch-up effect (ie a reducing stick force) which could lead the pilot to further increase the back pressure on the yoke and send the aircraft closer towards the stall. This non-linear/reducing stick force is not allowable under FAR §25.173 "Static longitudinal stability".

GM228

Hotblack Desiato wrote: »

Not according to these guys.

http://www.b737.org.uk/mcas.htm

+1 (though §25.173 is incorrect in your quote and is amended to §25.203).

From the FAAs Airworthiness Standards direct from the annual Code of Federal Regulations:-

§25.203 Stall characteristics.

(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.

https://www.govinfo.gov/app/details/CFR-2011-title14-vol1/CFR-2011-title14-vol1-sec25-203

Brennus335

CoisFharraige wrote: »

When power is applied to any aircraft, it will naturally raise the nose.

Not necessarily, it depends on the location of the thrust line relative to the CofG.

CoisFharraige wrote: »

In training in a 738 (I’d imagine most aircraft) they teach you to let the thrust adjust the attitude on approach

No swept wing jet aircraft uses thrust to control attitude on approach.
Pitch controls attitude, thrust controls speed.

Bill G

CoisFharraige wrote: »

In the MAX, since the engines are higher up, bigger, and further forward along the fuselage, this increase in power from the engines creates a strong tendency to pitch nose up more so than many other aircraft of its size. This could cause the aircraft to pitch up too dramatically and induce a stall, so MCAS was brought in to counteract this.

Thrust or power setting from the engines is not the reason MCAS was introduced. It is purely due to the fact that at high AoA, the vortex flow off the engine nacelles generate more lift. This increased lift in the MAX is forward of the CoG due to the engine placement. So, at high AoA, you get a pitch-up moment, which is non-certifiable.

http://www.b737.org.uk/mcas.htm

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Correct, otherwise MCAS would need to activate every time high thrust was applied in flight. Especially during a go-around, windshear event or terrain escape manoeuvre which doesn't trigger it.

Jeff2

Both crashes were shortly after take off.

swampgas

Reuters reporting that Boeing is being sued by shareholders:
https://www.reuters.com/article/us-ethiopia-airline-boeing-lawsuit/boeing-shareholders-sue-over-737-max-crashes-disclosures-idUSKCN1RL31D

According to the complaint, Boeing “effectively put profitability and growth ahead of airplane safety and honesty” by rushing the 737 MAX to market to compete with Airbus SE, while leaving out “extra” or “optional” features designed to prevent the Ethiopian Airlines and Lion Air crashes.

It also said Boeing’s statements about its growth prospects and the 737 MAX were undermined by its alleged conflict of interest from retaining broad authority from federal regulators to assess the plane’s safety.

josip

Not much chance of the shareholders who are suing, putting honesty before greed.
They're not suing because they didn't approve of Boeing's morals.
They're suing Boeing for the same reasons that they say in their claim they're suing Boeing :rolleyes:
I always understood that a company's primary responsibility towards its shareholders was to deliver profit and growth?

Hotblack Desiato

Jeff2 wrote: »

Both crashes were shortly after take off.

Yes and takeoff thrust would have been set near the start of the takeoff roll

Said it before, and quoted sources, MCAS is nothing to do with throttle movement or position

josip wrote: »

I always understood that a company's primary responsibility towards its shareholders was to deliver profit and growth?

Brand new aircraft falling out of the sky is not good for profit or growth...

MJohnston

josip wrote: »

Not much chance of the shareholders who are suing, putting honesty before greed.
They're not suing because they didn't approve of Boeing's morals.
They're suing Boeing for the same reasons that they say in their claim they're suing Boeing :rolleyes:
I always understood that a company's primary responsibility towards its shareholders was to deliver profit and growth?

Maybe, but a lack of safety and honesty from aircraft manufacturer will inevitably lead to lost profit and diminished growth. So even if you think that's a companies primary responsibility to shareholders, then they arguably shirked that responsibility here.

There's a similar thing happening over VW's emissions scandal:
https://uk.reuters.com/article/uk-volkswagen-emissions-trial/vw-investors-sue-for-billions-of-dollars-over-diesel-scandal-idUKKCN1LQ0WD

cnocbui

josip wrote: »

Not much chance of the shareholders who are suing, putting honesty before greed.
They're not suing because they didn't approve of Boeing's morals.
They're suing Boeing for the same reasons that they say in their claim they're suing Boeing :rolleyes:
I always understood that a company's primary responsibility towards its shareholders was to deliver profit and growth?

That is a complete and utter fallacy commonly put about by right wing Americans. Abiding by the law takes precedence over all financial considerations.

They often confabulate profit and growth into a justified prioritisation of short term financial benefit over long term benefit. The share holders and the families of those affected have every right to be concerned as to Boeing's apparent prioritisation of short term profit over both their legal obligations and long term financial considerations, where company reputation is of considerable significance.

galwayllm

I won't be getting on a 737 Max for a very very long time, if ever.

Pronto63

https://www.vox.com/business-and-finance/2019/3/29/18281270/737-max-faa-scandal-explained

Interesting read.

The FAA certainly don't come out of this smelling of roses.

Turbulent Bill

swampgas wrote: »

Reuters reporting that Boeing is being sued by shareholders:
https://www.reuters.com/article/us-ethiopia-airline-boeing-lawsuit/boeing-shareholders-sue-over-737-max-crashes-disclosures-idUSKCN1RL31D

Boeing's share price is close to its 1-year average, which is also near its 5-year high, even with obvious deficiencies becoming public. If shareholders were truly worried, they'd be voting with their feet.

Jeff2

Turbulent Bill wrote: »

Boeing's share price is close to its 1-year average, which is also near its 5-year high, even with obvious deficiencies becoming public. If shareholders were truly worried, they'd be voting with their feet.

Reminds me of BP and the oil leak.

cnocbui

Trump - the joke that keeps on giving...

In an early-morning post on Twitter, Trump, who owned the Trump Shuttle airline from 1989 to 1992 and is an aviation enthusiast, weighed in with his own advice.
Related Coverage

“What do I know about branding, maybe nothing (but I did become President!), but if I were Boeing, I would FIX the Boeing 737 MAX, add some additional great features, & REBRAND the plane with a new name. No product has suffered like this one. But again, what the hell do I know?” Trump tweeted.

Boeing 848 Profit

Boeing 737 Fixed

Boeing 321..

Boeing 737 Trump Edition

Airbusing A320b