Ethiopian Airlines Crash/ B737MAX grounding

dogmatix · 03-04-2019 02:58PM

Cloudio9 wrote: »

Yeah. Reminds me of Derry girls last night: "Who put 50p in the eejit?"

There was a poster over on the A380 cancelled thread who referred to airbus as “scarebus”, something to do with airbus not being as safe as boeing. Then the whole 737max story broke. Oh the irony… Strange thing is that the post has now vanished.

cson · 03-04-2019 04:08PM

Cloudio9 wrote: »

Report in the WSJ that prelim black box data shows that the ET crew did cut power to the stab trim....tried to manually trim.....but still couldn’t recover. They also reconnected power to the stab trim not clear why ......I guess in desperation.

https://www.wsj.com/articles/ethiopian-airlines-pilots-initially-followed-boeings-required-emergency-steps-to-disable-737-max-system-11554263276

There was an article somewhere quoting 40 seconds from onset of the issue to checklist it & resolve before the aircraft is uncontrollable. You could keep buying yourself 40 seconds by hitting an override button on the controls (?) though I think. Though I imagine that could easily be missed in the chaos and confusion of such a situation.

cnocbui · 03-04-2019 04:19PM

Another 787 with engine woes:

Pilots of a Jetstar 787 Dreamliner encountered problems with both engines of their passenger plane as they came into land at the Japanese city of Osaka on Friday.

Initial accounts of the incident indicate one of the Boeing 787's engines suffered fluctuations in speed on approach to the aircraft landing at Osaka's Kansai International Airport.

A short time later, the other GE-manufactured engine on Flight JQ15 briefly encountered the same problem, sources familiar with the matter said.

https://www.stuff.co.nz/travel/news/111743027/jetstar-787-suffers-problems-with-both-engines-on-approach-to-osaka

Tenzor07 · 03-04-2019 05:34PM

dogmatix wrote: »

Surely an issue for Rolls-Royce rather then Boeing?

As far as I know, Airlines purchase the aircraft complete from Boeing and not RR...

L1011 · 03-04-2019 05:40PM

Tenzor07 wrote: »

As far as I know, Airlines purchase the aircraft complete from Boeing and not RR...

They generally buy or lease the engines in a separate contract to the airframe.

Hotblack Desiato · 03-04-2019 06:22PM

.. and the cost of replacement parts/engines and compensation for AOG will end up at RR's door one way or the other

Brennus335 · 03-04-2019 06:51PM

dogmatix wrote: »

There was a poster over on the A380 cancelled thread who referred to airbus as “scarebus”, something to do with airbus not being as safe as boeing. Then the whole 737max story broke. Oh the irony… Strange thing is that the post has now vanished.

Yeah, it was the same eejit.

Brennus335 · 03-04-2019 06:53PM

cnocbui wrote: »

I would have thought that the optional warning light to announce a conflict between the two AOA sensors should just about be mandatory now. Not something that can be provided via software.

The media always calls these things "warning lights". It's not an actual physical light like something out of 1960's Star Trek.
It's just a text message on a screen. All done by software.

billy few mates · 03-04-2019 06:55PM

Depending on the position of the horizontal stabiliser when they operated the stab trim cutout switches it may be that the elevators did not have the authority to overcome the stab trim?
For example if there was already full nose down stab trim when you switch off the motors the elevators by themselves would not be able to overcome the nose down pitch hence the attempt to manually trim the stab to try and get the nose back up.
Absolutely tragic.

Raging_Ninja · 03-04-2019 07:24PM

cnocbui wrote: »

Another 787 with engine woes:

https://www.stuff.co.nz/travel/news/111743027/jetstar-787-suffers-problems-with-both-engines-on-approach-to-osaka

This is something that happens probably a thousand times a day.

Edit: my assertion is incorrect.

odyssey06 · 03-04-2019 07:38PM

Brennus335 wrote: »

The media always calls these things "warning lights". It's not an actual physical light like something out of 1960's Star Trek.
It's just a text message on a screen. All done by software.

If that is the case Boeing trying to charge hundreds of thousands of dollars for it as an optional extra is even more outrageous.

Tenzor07 · 03-04-2019 08:11PM

odyssey06 wrote: »

If that is the case Boeing trying to charge hundreds of thousands of dollars for it as an optional extra is even more outrageous.

Hundreds of thousand$$ for a light? Are you sure?

odyssey06 · 03-04-2019 08:16PM

Tenzor07 wrote: »

Hundreds of thousand$$ for a light? Are you sure?

On second thoughts no... unclear how much but if it is similar to the extras noted here more like 10k
https://www.google.com/amp/s/www.nytimes.com/2019/03/21/business/boeing-safety-features-charge.amp.html

mickdw · 03-04-2019 08:17PM

80,000 dollars was quoted here earlier.

Tenger · 03-04-2019 08:34PM

mickdw wrote: »

80,000 dollars was quoted here earlier.

Quotes varied as the cost was a fraction of the overall price per airframe. Obviously Boeing has a “list price” and each customer negotiates that price down depending on their clout with Boeing, their order size, their after sales support and their delivery slots.
Thus it could be 200K on a last minute, in a rush small order versus the 100s of airframes ordered by Southwest/Ryanair for delivery over 5-10 years.

mickdw · 03-04-2019 08:56PM

Tenger wrote: »

mickdw wrote: »

80,000 dollars was quoted here earlier.

Quotes varied as the cost was a fraction of the overall price per airframe. Obviously Boeing has a “list price” and each customer negotiates that price down depending on their clout with Boeing, their order size, their after sales support and their delivery slots.
Thus it could be 200K on a last minute, in a rush small order versus the 100s of airframes ordered by Southwest/Ryanair for delivery over 5-10 years.

So realistically it's just down to customer specification as to whether it was included or not and not necessarily a cost issue.
The important point is though that if it's a safety critical item, it should be standard fit.

cnocbui · 03-04-2019 09:35PM

Raging_Ninja wrote: »

This is something that happens probably a thousand times a day.

I don't believe you, frankly.

The Jetstar 787 remains grounded at Kansai International Airport while it is inspected by engineers from the airline, General Electric and Boeing.

The ministry classified the situation as a “serious incident” that could have led to a major accident, adding that although there were no reports of injuries it has decided to send inspectors to the airport to look into the plane, which was from the northern Australian city of Cairns.

https://www.japantimes.co.jp/news/2019/04/03/business/jetstar-787-serious-engine-trouble-landing-kansai-international-airport/

cnocbui · 03-04-2019 09:45PM

billy few mates wrote: »

Depending on the position of the horizontal stabiliser when they operated the stab trim cutout switches it may be that the elevators did not have the authority to overcome the stab trim?
For example if there was already full nose down stab trim when you switch off the motors the elevators by themselves would not be able to overcome the nose down pitch hence the attempt to manually trim the stab to try and get the nose back up.
Absolutely tragic.

Please tell me the trim tab isn't actuated by a long threaded shaft attached to a motor with a 'nut' on the shaft attached to the tab?

Cutting power would just lock something like that it in the wrong position. You would need something like an explosive bolt to decouple such a mechanism in an emergency.

Irish Steve · 03-04-2019 09:53PM

Raging_Ninja wrote: »

This is something that happens probably a thousand times a day.

No, this is very much NOT a regular or even irregular occurrence, and is being regarded as a serious incident. The aircraft is currently grounded and being inspected, they will be looking very closely at a number of data recorder captures to see what went on, and why, as this is very much not an expected or routine event.

Coil Kilcrea · 03-04-2019 10:07PM

cnocbui wrote: »

I don't believe you, frankly.

https://www.japantimes.co.jp/news/2019/04/03/business/jetstar-787-serious-engine-trouble-landing-kansai-international-airport/

I flew on the 787 last week and will do the same next week to Japan. Much and all as I love the airplane, these issues nag at me. Anyone here know why this problem with the Trent engines seems to be never ending? And I appreciate it’s rare enough but it’s still troubling. Thanks.

Jeff2 · 03-04-2019 10:07PM

cnocbui wrote: »

Please tell me the trim tab isn't actuated by a long threaded shaft attached to a motor with a 'nut' on the shaft attached to the tab?

Cutting power would just lock something like that it in the wrong position. You would need something like an explosive bolt to decouple such a mechanism in an emergency.

I believe it is but there is a way the pilot can manually control it after switching it off.

I'll look for where I got that from.

Found it.
4.30 minutes in.

https://www.youtube.com/watch?v=xixM_cwSLcQ

plodder · 03-04-2019 10:14PM

Coil Kilcrea wrote: »

I flew on the 787 last week and will do the same next week to Japan. Much and all as I love the airplane, these issues nag at me. Anyone here know why this problem with the Trent engines seems to be never ending? And I appreciate it’s rare enough but it’s still troubling. Thanks.

787 uses GE engines not the Trent which is Rolls Royce.

Coil Kilcrea · 03-04-2019 10:18PM

plodder wrote: »

787 uses GE engines not the Trent which is Rolls Royce.

I think it’s the Rolls Royce Trent but sorry for posting on the 737 Max thread which might be causing confusion.

plodder · 03-04-2019 10:22PM

Coil Kilcrea wrote: »

I think it’s the Rolls Royce Trent but sorry for posting on the 737 Max thread which might be causing confusion.

Actually, the 787 supports both, but the Jetstars mentioned in the article used the GE engine afaik.

Coil Kilcrea · 03-04-2019 10:28PM

JP Morgan reporting today that the cost to Boeing of the disruption caused by the Max grounding will likely cost between 1.7 to 2 Billion dollars a month. Build of the Max is continuing at an increased rate of 56 per month. That’s an an awful lot of working capital wrapped up in an aircraft that may have to be parked for a while.

Airlines typically pay a deposit with the order and then stage payments through build and final delivery. And while Boeing is a cash generating machine when all is well, it burns enormous cash when deliveries are disrupted. So while they’ve deep pockets, the pressure commercially to get back in the air conflicts with the necessity to ensure the plane is safe for flight.

I don’t see this happening as fast as the company would like.

Irish Steve · 03-04-2019 10:34PM

cnocbui wrote: »

Please tell me the trim tab isn't actuated by a long threaded shaft attached to a motor with a 'nut' on the shaft attached to the tab?

Cutting power would just lock something like that it in the wrong position. You would need something like an explosive bolt to decouple such a mechanism in an emergency.

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.

MJohnston · 03-04-2019 10:41PM

https://arstechnica.com/information-technology/2019/04/ethiopian-air-pilots-turned-off-737-max-anti-stall-system-then-it-turned-on-again/

Data from the ill-fated aircraft’s flight recorder revealed that the anti-stall feature of the aircraft’s MCAS was triggered at least three times—and at least one time after the pilots followed the correct steps to shut it down.

Both Reuters and The Wall Street Journal report that the air crew followed procedures laid out by Boeing following the crash of a Lion Air 737 MAX in October, according to officials briefed on the initial findings of the investigation. But the pilots failed to regain control of the system, and the MCAS was reactivated again—triggering yet another automated correction of the aircraft’s stabilizers that would have pushed the nose of the plane down.

It is not clear at this point whether the pilots purposely reactivated the MCAS’ stabilizer control or if the software reactivated on its own after shutdown. While a Wall Street Journal source said that it appeared the pilots turned the system back on in hopes of regaining control over the stabilizers, Reuters reports that the software may have reactivated without human intervention, and further investigations of that possibility are ongoing.

Coil Kilcrea · 03-04-2019 10:42PM

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.

Thanks Irish Steve for a great post. I can only imagine how difficult it must be for the pilots to manage this process whilst in the critical take off and climb phase of the Ethiopian flight. My long held admiration of pilots continues.

cnocbui · 03-04-2019 11:05PM

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

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.

Thanks, I was watching the other video and it confirmed my fears. I'm gobsmacked, actually. That is a fail dangerous system, not fail safe. So the MCAS system keeps incrementing the trim by 4 times the stated design amount, with multiple cumulative iterations, doing so with the benefit of high speed electric motors, so when a pilot offs the stab trim switches, the pilot/s are left to manually unwind that large trim deflection by operating the screw - via the trim wheel handle - through many, many rotations?

Surely that process is far too slow if you are nose down with not much altitude?

Raging_Ninja · 04-04-2019 06:23AM

Irish Steve wrote: »

No, this is very much NOT a regular or even irregular occurrence, and is being regarded as a serious incident. The aircraft is currently grounded and being inspected, they will be looking very closely at a number of data recorder captures to see what went on, and why, as this is very much not an expected or routine event.

Thanks for the correction, will update my post.

Ethiopian Airlines Crash/ B737MAX grounding

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