Another Country Grounds The 737-MAX

[tamada]

The larger engines and shorter engine pylons have altered the centre of gravity of the Max 8, something that is probably more critical during take-off. I understand that MCAS was developed to address this.

Sorry MCAS isn't functional during takeoff. It is disabled by the flaps being extended. It only comes into play once the flaps are retracted. As I have said it can only function during climb out, though that may well have been caused by A faulty AOT sensor (probably was in Lion Air), and during flight when the autopilot is off.IMG_7073.JPG

Good posts. For the layman traveler, take-off ends when the seatbelt light goes off and the plane is (almost) at cruising altitude. Deployed flaps disable MCAS but depending on how quickly the aircraft is being taken through climb-out, the flaps will be retracted sooner, no? Do you know if MCAS automatically senses the amount of flap and kicks-in unannounced or does it only activate once the flaps are fully retracted? The Lion Air flight had issues during climb out and the same issues may have affected the Ethiopian flight which, due to the altitude of Addis, thinner air and other aerodynamics, may already have been on a more accelerated climb-out?

[saint]

So as a layman am i correct in assuming that there was a basic design fault with the plane , and Boeing decided that this MCAS thingy was a quick or cheap fix ?

[sometimewoodworker]

So as a layman am i correct in assuming that there was a basic design fault with the plane , and Boeing decided that this MCAS thingy was a quick or cheap fix ?

No design fault AFIK, the characteristics of the planes design made certain actions of the pilot cause the plane to pitch up quite a lot which in a different plane would not have caused such degree of inclination.

MCAS was part of the original design. It originally only worked in 0.6 degree increments, this was increased during flight testing to work in 2.5 degree increments as the amount of increased angle of attack was found to be greater than was assumed during the design stage.

[Jing Jing]

Whether the MCAS was part of the original design does not help the fact the whole project was wrong. Boeing did not want to build a new airplane due to cost and timing. Boeing stuck larger more fuel efficient engines on a plane that was not originally designed to take this size engine. Airbus also did the same thing with their A320 Neo. By sticking larger engines on an existing plane Boeing hoped to cut the certification and trading process. These were selling points to the airline. A more fuel efficient plane that did not require pilot certification. Training in some cases consisted of using a tablet towatch videos.

[tamada]

So as a layman am i correct in assuming that there was a basic design fault with the plane , and Boeing decided that this MCAS thingy was a quick or cheap fix ?

No design fault AFIK, the characteristics of the planes design made certain actions of the pilot cause the plane to pitch up quite a lot which in a different plane would not have caused such degree of inclination.

MCAS was part of the original design. It originally only worked in 0.6 degree increments, this was increased during flight testing to work in 2.5 degree increments as the amount of increased angle of attack was found to be greater than was assumed during the design stage.

To put this technical jargon in layman's terms, the rate of nose-down that MCAS forced on the tailplane jackscrew was several orders of magnitude higher than any amount of counteracting, manual spinning of the trim wheels in the flight deck by the flight crew.

That's the point where the revised manual says they're supposed to flip the MCAS breakers and pull up.

[tamada]

... Airbus also did the same thing with their A320 Neo. ...

Yes but the original A320 already had taller undercarriage and higher-mounted wings than the 737 and could readily accept the larger circumference engines without the need to shorten the pylons or 'squash' the bottom edge of the engine nacelles.

A320Neo

737 Max

[sometimewoodworker]

Good posts. For the layman traveler, take-off ends when the seatbelt light goes off and the plane is (almost) at cruising altitude. Deployed flaps disable MCAS but depending on how quickly the aircraft is being taken through climb-out, the flaps will be retracted sooner, no? Do you know if MCAS automatically senses the amount of flap and kicks-in unannounced or does it only activate once the flaps are fully retracted? The Lion Air flight had issues during climb out and the same issues may have affected the Ethiopian flight which, due to the altitude of Addis, thinner air and other aerodynamics, may already have been on a more accelerated climb-out?

MCAS does not function while the flaps are extended. It only activates once the flaps are fully retracted.

As you can see from the graphic I posted it is the airspeed that governs the retraction of the flaps.

The hight and time into climb out at which flaps are retracted is dependent on the plane, noise abatement procedures, airport, takeoff direction, wind speed, wind direction and company fuel conservation policy. It is typically between 1,000' and 3,000’

I haven't found any noise abatement procedures for Bole airport which may mean that the Max reached total flap retraction speed quickly.

The most efficient is a full power climb with minimum flaps for the airspeed according to

Fuel Conservation Strategies: Takeoff and Climb

By William Roberson, Senior Safety Pilot, Flight Operations; and James A. Johns, Flight Operations Engineer, Flight Operations Engineering

[pipoz4444]

Watch this, if true, it just makes you wonder even more, about Boeing's design

Alternating from one side to the other after each flight or in this case after a Test/Check, back to a defective one??

https://www.youtube.com/watch?v=4koccb8suOQ

pipoz4444

[sometimewoodworker]

Watch this, if true, it just makes you wonder even more, about Boeing's design

Alternating from one side to the other after each flight or in this case after a Test/Check, back to a defective one??

https://www.youtube.com/watch?v=4koccb8suOQ

pipoz4444

As you say, if true, and if what is claimed about the non documentation of this in the maintenance information, it makes the fault even more clearly a Boeing one. I know that writing maintenance manuals is not easy and is expensive but there is no conceivable reason for the omission.

[Jing Jing]

“U.S. air-safety regulators have tentatively approved sweeping software and pilot-training changes for Boeing Co.’s grounded 737 MAX jets, aimed at fixing problems with a suspect flight-control system, according to internal government documents and people familiar with the details.” NY Times

Boeing appears to be fixated on slapping together a quick fix rather than waiting for the final crash reports or reviewing the whole flight system. I don’t think Boeing has enough information at this point to say MCAS software tweaks are all that is needed.

Again more pilot training is based on an iPad application not actual flight simulator training

[papafarang]

"Boeing appears to be fixated on slapping together a quick fix rather than waiting for the final crash reports or reviewing the whole flight system"

they don't need the report , they knew the MCAS system was dangerous , that's why they update software. who has not seen their computer crash because of a software issue...mind you a home computer with software problems don't ditch you into the ground at 450 miles an hour and then incinerate you with jet fuel

[tamada]

Good summary here.

https://www.vox.com/business-and-financ ... -explained

[fdimike]

You certainly won't find me on one of these 737s. Why would anyone trust anything Boeing has to say about the safety of these planes?

[tamada]

I think we are lucky over this side of the planet as outside of Lion Air and their local offshoots, most local and regional airlines seem to have bought into the Airbus A318, A319, A320 and A321 variants. ThaiSmile, Bangkok Airways, VietJet and AirAsia gets my business. For long haul, the 777 is immensely safe but note that in the fallout from the Ethiopian crash, Boeing had to 'bury' the roll-out of the 777X which is a (even more) stretched version of the 26 year-old air frame.

Are we seeing a trend here?

[Udon Map]

I think we are lucky over this side of the planet as outside of Lion Air and their local offshoots, most local and regional airlines seem to have bought into the Airbus A318, A319, A320 and A321 variants....

Don't forget Nok. Nearly all 738s.

For long haul, the 777 is immensely safe but note that in the fallout from the Ethiopian crash, Boeing had to 'bury' the roll-out of the 777X which is a (even more) stretched version of the 26 year-old air frame.

Interestingly (for avgeeks), the 777X will become the longest passenger aircraft at 76.7 meters, closely followed by the 748 at 76.3 meters and the Airbus 346 at 75.36 meters.

[Jing Jing]

Two minutes after it departed from Addis Ababa's highland airport on its scheduled one hour and 40 minute shuttle to Nairobi, things began to go very wrong, according to the Wall Street Journal. At 8:39, with the jet just 450 feet above the ground, its nose began to pitch down. First Officer Ahmednur Mohamed radioed the control tower to report a "flight-control problem."

No matter how many warning lights there might have been the pilots had no time to react. The problem with MCAS may not only be software but might include mechanical or electrical problems. Other planes that were built at the same time as the Lion Air and Ethiopian Airlines planes should be examined.

[fdimike]

All 737 max planes are now grounded to the best of my knowledge. Are you suggesting that some of Boeings other planes may be affected?

[sometimewoodworker]

Regrettably my post has been edited so it now is not anything similar to my actual posting.

I have therefore deleted the incorrect post

[fdimike]

I certainly have no confidence in Being's ability to correct the problem and train the pilots properly. Boeing knew about this problem long ago but did not include the technology nor pilot training in their 737s unless the airline was willing to pay for it.

[papafarang]

it's a botched design , putting engines on never designed to work with such an old design, and then hoping software will keep it up in the air. How did that work out