Ethiopian Airlines Crash/ B737MAX grounding

Wheeliebin30 · 04-04-2019 06:51AM

In the headlines from a leaked report it was hit by an object that sent it into a dive?

https://www.buzz.ie/news/ethiopian-airlines-boeing-737-hit-object-causing-crash-322582?fbclid=IwAR10L3wNWnFTLZ8XV_44r4C7fH8oRyNGrzX6U9CaAX2B4mRgl67vkdBc-Qs

Raging_Ninja · 04-04-2019 07:26AM

Wheeliebin30 wrote: »

In the headlines from a leaked report it was hit by an object that sent it into a dive?

https://www.buzz.ie/news/ethiopian-airlines-boeing-737-hit-object-causing-crash-322582?fbclid=IwAR10L3wNWnFTLZ8XV_44r4C7fH8oRyNGrzX6U9CaAX2B4mRgl67vkdBc-Qs

Well, something had to break the AoA sensor in order for MCAS to activate and crash the plane.

Wheeliebin30 · 04-04-2019 07:42AM

Raging_Ninja wrote: »

Well, something had to break the AoA sensor in order for MCAS to activate and crash the plane.

Yeah true I was under the impression it was just a faulty sensor.

Stimpyone · 04-04-2019 09:17AM

Raging_Ninja wrote: »

Well, something had to break the AoA sensor in order for MCAS to activate and crash the plane.

buzz.ie quotes ABC news as the source. ABC news quotes two unnamed aviation sources familiar with the investigation.

Tin foil hat time, but I'm guessing an incident beyond Boeings control causing the crash would be advantageous in any future investigations, law suits or sales.

I'd hold my powder just yet.

ZiabR · 04-04-2019 09:41AM

News just breaking.

Pilots "repeatedly" followed procedures recommended by Boeing before last month's crash of an Ethiopian Airlines flight, according to the first official report into the disaster.

https://www.bbc.com/news/business-47812225

The problem as I see it though is that the pilots didn't have the correct training to deal with MCAS.

Expect more information to follow later today.

More news: https://www.bbc.com/news/business-47812225

Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

This is a carbon copy of the Lion Air flight. Plane nosedived numerous times before eventually crashing.

zilog_jones · 04-04-2019 10:23AM

ZiabR wrote: »

The problem as I see it though is that the pilots didn't have the correct training to deal with MCAS.

I wouldn't say that at all. Going by what I've read here, they did follow the correct procedure of overriding the stab trim, but this means having to manually wind back the stabilisers with these big wheels - the physical effort required to do this, while also controlling the yoke (which requires significant force in this situation), when you only have 40 seconds, sounds pretty much impossible to do with two people.

As we've heard there was an MCAS incident that was resolved on a Lion Air flight before the crash - but there were three people in the cockpit at the time.

Hotblack Desiato · 04-04-2019 10:30AM

Stimpyone wrote: »

Tin foil hat time, but I'm guessing an incident beyond Boeings control causing the crash would be advantageous in any future investigations, law suits or sales.

Sensors fail. A single failed sensor should not threaten to bring down an aircraft.

Stimpyone · 04-04-2019 11:25AM

Hotblack Desiato wrote: »

Sensors fail. A single failed sensor should not threaten to bring down an aircraft.

Agreed.

jasper100 · 04-04-2019 12:07PM

Stimpyone wrote: »

Agreed.

= manufacturer at fault. Which contradicts your earlier "guess" that it leaves manufacturer off the hook to some degree.

It won't

Tenzor07 · 04-04-2019 12:21PM

Boeing's CEO takes flight in a Max yesterday:

https://www.airlineratings.com/news/boeing-ceo-muilenburg-aboard-737-max-test-flight/

josip · 04-04-2019 12:47PM

Tenzor07 wrote: »

Boeing's CEO takes flight in a Max yesterday:

https://www.airlineratings.com/news/boeing-ceo-muilenburg-aboard-737-max-test-flight/

Do they have parachutes on board test flights? (Genuine question)

Man Vs ManUre · 04-04-2019 12:54PM

josip wrote: »

Do they have parachutes on board test flights? (Genuine question)

Don’t think there would be an exit point on these large commercial planes that would be safe to jump from without being hit by engines, other plane part. You can probably only jump from the rear cargo bottom opening on those type of planes.
Also no eject option like with fighter planes.
These test pilots for Boeing and Airbus are probably ex fighter pilots and the elite. Still must be a very dangerous job to do. They fly the planes in ways that would terrify a passenger if it happened.

elmolesto · 04-04-2019 01:00PM

josip wrote: »

Do they have parachutes on board test flights? (Genuine question)

Airbus pilots carry them for the flutter test.

https://youtu.be/s3-g9B6Fgjs

TomSweeney · 04-04-2019 01:59PM

Wheeliebin30 wrote: »

If this finishes Boeing off what does that mean for the future of flying?

Airbus will cash in on it I'd imagine

Panrich · 04-04-2019 06:17PM

Sky reporting that the pilots followed Boeing process to deal with the MCAS error and that they eventually turned off MCAS but that it turned itself back on. This is from the report by the Ethiopian authorities.

billy few mates · 04-04-2019 07:20PM

josip wrote: »

Do they have parachutes on board test flights? (Genuine question)

I've heard of a Boeing 737 test flight with Boeing test pilots where they wore parachutes and had some sort of a special device fitted to the door to blow it open in case of emergency...

billy few mates · 04-04-2019 07:32PM

Irish Steve wrote: »

No, it's not at all like that, there are 2 wheels, about 12" diameter, either side of the centre console, and there is a fold out handle in each wheel to enable manual winding.
They are then linked via cables to a winding system, the problem being that it requires a massive number of turns of the wheel to make a significant change to the trim of the aircraft, the motors move the wheels at a very high revolution rate compared to what can be done winding them by hand, and if the aircraft is significantly out of trim, the control column loads are significant, which can require both hands of the flying pilot to be on the yoke to apply sufficient force to overcome the out of trim load, leaving the non flying pilot to operate the handle and wind as quickly as possible.

example
https://www.youtube.com/watch?v=cQirIH_DuAs

It's a very short video, but this gives an idea of how fast the wheel moves if the motor is in control. Now imagine that the motor has been running for several seconds, and you now have to manually undo what it's done, while at the same time, performing check list work to try and analyse and resolve the problem that's threatening to crash the aircraft.

Not easy, or quick, or the sort of thing that the non flying pilot is prepared for, and to make it worse, the flying pilot is probably more than fully committed to just trying to keep the control yoke in about the right place to maintain stable flight, and constantly trying to overcome the out of trim forces.

That's not an entirely accurate representation of the automatic trim system.
There are two servo motors installed on the base of the screwjack, the main electric trim servo motor is larger than the autopilot trim servo motor.
What you're seeing is the main electric trim motor trimming the stab (via the pickle switches). The auto pilot trim servo motor doesn't trim as fast as that and doesn't trim through the same range. I can't remember the exact figures but the autopilot trim servo can trim it X number of degrees nose down and y number of degrees nose up but the main electric trim motor can trim it a few degrees further in either direction and the manual trim wheels can trim it even further in each direction, it's all controlled by limit switches.
Next time you're on a 737 (on the ground) trim it forward or aft to the stops and then see how much further you can wind it on manually.
Then try engaging the autopilot on the ground, push the control column forward and watch how much slower the autopilot trim servo trims the stab.

Jeff2 · 04-04-2019 10:00PM

I posted a picture of the trim from the inside that was a screenshot from a video I posted and it's been deleted.

If I did wrong I didn't know but I'v a pm that I can't access for some reason, maybe mods can delete sent pms.

Irish Steve · 04-04-2019 10:09PM

billy few mates wrote: »

That's not an entirely accurate representation of the automatic trim system.

Understood, the main reason for posting was to try and make it clear for the non pilots that the wheel is a large item, and moves relatively quickly over a long range of travel, with the emphasis being on that if the motors are no longer available to drive the trim, and the crew are forced to revert to manual winding using the handles, that's a relatively slow process, made more difficult if the aircraft is badly out of trim, as significant out of trim loads on the yoke are likely to require a lot of manual effort to manage them. Fully understand that normally, the automatic trim moves more slowly.

I don't have experience of the differences that came about as a result of the MCAS changes with the MAX, but it would seem from as yet unsubstantiated comments that the MCAS is not a user friendly system.

I also don't have any details of how quickly it applies the change of pitch to the system in comparison to the older and more widely known trim systems.

What is clear is that there are some very worrying unanswered questions that have to be answered before the MAX can be put back into commercial operation, and a quick fix will not be acceptable to many regulators, or potential passengers.

Irish Steve · 04-04-2019 10:11PM

Jeff2 wrote: »

I posted a picture of the trim from the inside that was a screenshot from a video I posted and it's been deleted.

If I did wrong I didn't know but I'v a pm that I can't access for some reason, maybe mods can delete sent pms.

It was deleted because the link was incorrect, and went to an error page on the external site. By all means try it again, but please check after posting that it is working correctly.

Coil Kilcrea · 04-04-2019 10:49PM

TomSweeney wrote: »

Airbus will cash in on it I'd imagine

For sure, but Boeing will batten down the hatches, take the inevitable battering and get back to business. Too big to fail springs to mind.

I do think that the revenue acceleration that followed the Max order book will take a hammering and that the 797 plans are probably being dusted off.

Hotblack Desiato · 04-04-2019 11:01PM

Airbus's order book for the 320 family is full for years, so they won't directly benefit. Secondhand/lease prices will go up, but that was happening anyway due to industry growth (and a recession will quickly reverse that)

Boeing have a huge order book for the MAX too, and I doubt they'll see more than a small number of cancellations. Costs of changing your fleet from one to the other are huge, running a mixed fleet is inefficient and operationally inflexible

It'll probably boil down to Airbus being able to play a bit more hardball on negotiations for future orders, Boeing having to sweeten deals a bit more.

Steve · 04-04-2019 11:08PM

Sorry if already posted, the preliminary report makes for some interesting reading.

http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+B737-800MAX+%2C%28ET-AVJ%29.pdf/4c65422d-5e4f-4689-9c58-d7af1ee17f3e

Notable imo are the stabilizer trim adjustments and whether they were manual or from the AND after it was disabled.

Turbulent Bill · 04-04-2019 11:27PM

Hotblack Desiato wrote: »

Airbus's order book for the 320 family is full for years, so they won't directly benefit. Secondhand/lease prices will go up, but that was happening anyway due to industry growth (and a recession will quickly reverse that)

Boeing have a huge order book for the MAX too, and I doubt they'll see more than a small number of cancellations. Costs of changing your fleet from one to the other are huge, running a mixed fleet is inefficient and operationally inflexible

It'll probably boil down to Airbus being able to play a bit more hardball on negotiations for future orders, Boeing having to sweeten deals a bit more.

Agreed, Boeing and Airbus form a duopoly and it's in both of their interests to keep this going. Airbus took a financial hit on the A380, same for Boeing on the MAX, but overall I wouldn't see either being seriously damaged long term.

Damien360 · 04-04-2019 11:29PM

Steve wrote: »

Sorry if already posted, the preliminary report makes for some interesting reading.

http://www.ecaa.gov.et/documents/20435/0/Preliminary+Report+B737-800MAX+%2C%28ET-AVJ%29.pdf/4c65422d-5e4f-4689-9c58-d7af1ee17f3e

Notable imo are the stabilizer trim adjustments and whether they were manual or from the AND after it was disabled.

Read this and page 18 stands out. Stab trim switch in override position allows electric trim to still be active and I assume regardless of switch being in cutout or not. So they confirmed it was off according to conversation but what position was that switch in and did it still engage nose down.

No aviation experience so can someone correct me if I read wrong.

Jeff2 · 04-04-2019 11:42PM

Right I'll try again for picture of inside of trim mechanism.

prQPm8d

GM228 · 05-04-2019 07:06AM

Panrich wrote: »

Sky reporting that the pilots followed Boeing process to deal with the MCAS error and that they eventually turned off MCAS but that it turned itself back on. This is from the report by the Ethiopian authorities.

Is that accurate though?

Surely the system can't, or at least should not be able to turn itself on after specifically being disabled, sounds like a sci-fi TV show where AI has evolved and gone rogue.

GM228 · 05-04-2019 07:13AM

Hotblack Desiato wrote: »

Airbus's order book for the 320 family is full for years, so they won't directly benefit.

Their book is full with build and delivery time estimates most likely based (at the time) on the assumption the A380 production and assembly lines could be still open, I wonder with that line closing in two years or so will they be able to ramp up production and assembly of other airframes, after all there are a lot of staff and facilities solely dedicated to the A380. Surely the recent announcement on the A380s requires a re-estimated timeframe for the other products and allows for more/quicker orders and a bit of scope to potentially take what otherwise could have been Boeing orders.

GM228 · 05-04-2019 07:31AM

Hotblack Desiato wrote: »

Costs of changing your fleet from one to the other are huge, running a mixed fleet is inefficient and operationally inflexible

That very much depends on the airline and the scale of their operations, look at AA, yes they are huge compared to the average airline, but up to a few years ago they were near 100% Boeing, in the last number of years they have become 51% Boeing and 43% Airbus (the rest being Embraer and MD).

Muahahaha · 05-04-2019 08:26AM

There were reports in some media yesterday that the pilots turned off the MCAS but somehow it turned itself back on which sounds bizarre. Did the report bear this out and if it did happen does it make this crash unique, i.e. a software system crashing a plane not because of failure to operate but instead operating when it had been commanded not to

Ethiopian Airlines Crash/ B737MAX grounding

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