Go Back  PPRuNe Forums > Flight Deck Forums > Rumours & News
Reload this Page >

Ethiopian airliner down in Africa

Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots.

Ethiopian airliner down in Africa

Old 12th Mar 2019, 22:50
  #861 (permalink)  
 
Join Date: Sep 2012
Location: Europe
Posts: 191
Originally Posted by atakacs View Post
Does anyone know if the EASA notice is based on some new input (presumably from early readout of Ethiopian FDR) ?
If not I think this is draconian and frankly unwarranted - they could at the very least allow en-route flights to operate normally as the issue - if there is actually one - is in the takeoff phase.
We don't know what caused the crash of the Ethiopian plane. So how can you know for a fact that whatever issue possibly is at play, only exists in the take-off phase? Perhaps it is a failure mode that can pop-up in any phase and turn a 737 MAX into an impact crater for CEOs to rummage through. We simply don't know, so safety should be the main priority here.

Intrance is offline  
Old 12th Mar 2019, 22:54
  #862 (permalink)  
 
Join Date: Jul 2013
Location: Norway
Age: 53
Posts: 127
Originally Posted by DaveReidUK View Post
Updated FAA statement:

FAA seems to be incredibly stubborn. Interesting to see how it pans out in the end.
SteinarN is offline  
Old 12th Mar 2019, 22:55
  #863 (permalink)  
 
Join Date: May 2010
Location: PLanet Earth
Posts: 821
Originally Posted by KRUSTY 34 View Post
Perhaps, but one has to ponder that the inevitable class action arising from both crashes, along with the evaporation of sales, will certainly test the theory of “Too big to fail”.
At least this will probably hit hard. Will not be so easy (and take Years) to restore trust of the travelling public into the MAX. It had a hard time against the NEO before this. After this it will be even much harder to cope with the NEO.
henra is offline  
Old 12th Mar 2019, 22:56
  #864 (permalink)  
 
Join Date: Jul 2007
Location: the City by the Bay
Posts: 528
Originally Posted by DaveReidUK View Post
Updated FAA statement:

The FAA is doubling down.
armchairpilot94116 is offline  
Old 12th Mar 2019, 22:56
  #865 (permalink)  
 
Join Date: May 2000
Location: London, UK
Posts: 364
It seems the issue is not so much with MCAS as with the engine location relative to the wing.

MCAS reads like a half baked solution to a problem that should not be there in the first place.

If so, this is not the kind of design philosophy I associate with Boeing.

Diverting aircraft in the cruise because they have a problem taking off doesn’t sound like a terribly rational response either.
SLF3 is offline  
Old 12th Mar 2019, 23:01
  #866 (permalink)  
 
Join Date: Mar 2006
Location: Vance, Belgium
Age: 58
Posts: 181
Originally Posted by AlexGG View Post
But my understanding is that these switches do not stop MCAS activity. Is that correct?
That's also my understanding : "control column actuated trim cutout switches" have no effect on MCAS while the "stabilizer trim cutout switches" on the control stand do stop MCAS.
(I understand that it's the AUTOPILOT Cutout switch that does the job).
But I am not a B737 pilot, so I am happy to stand corrected.
Luc Lion is offline  
Old 12th Mar 2019, 23:08
  #867 (permalink)  
 
Join Date: Aug 2017
Location: United States
Posts: 11
Yes - This ban is not being followed by carriers even if the country has grounded the aircraft over there airspace.
FanControl is offline  
Old 12th Mar 2019, 23:12
  #868 (permalink)  
 
Join Date: Jul 2005
Location: btw SAMAR and TOSPA
Posts: 565
EASA became crazy

Originally Posted by LookingForAJob View Post
I openly admit that I am no fan of the way in which EASA works - being overly reliant on rules and law with sometimes peculiar interpretations of that law - but it's strange to see, following rather than leading, its member States' CAAs, that it chooses to issue an AD which appears to fail to meet the legal requirements set out in Commission Regulation No 748/2012 for such documents.

Of course, if evidence shows that the safety level of this aircraft may be compromised I would hope that this would be declared, even if the details of that evidence are not provided. Overall, as others have suggested, this is a situation which is being driven by public opinion (which may include a good many pilots). Those who claim that it's driven by safety I fear may be deluding themselves. I'm not suggesting that it is wrong that these aircraft are being grounded, but actions are hardly being led by the agencies that are established to protect the travelling and innocent ground-dwelling public.
I agree. A grounding is certainly justified but using an AD for this is ridicolous. Moreover a number of B38M returning flights, that were airborne and at cruising levels, had to divert because of a stupid AD deadline at 19 UTC, leaving hundreds of European citizens somewhere abroad. EASA is a political nonsense tool as much as FAA became a commercial tool.
threemiles is offline  
Old 12th Mar 2019, 23:13
  #869 (permalink)  
 
Join Date: Feb 2019
Location: MOW
Posts: 34
Originally Posted by Charley View Post
The FZ8xxx callsigns are empty (non-revenue) positioning flights. Both FlightStats and each airports websites confirmed the flights they should have been making were cancelled.

The flight out of Kiev though does have pax aboard. Wonder if it will be held short of the Bucharest or Sofia FIR/UIRs in the same was as the earlier QS flight was.
Bucuresti FIR to FZ730: Thou shall not pass.
jantar99 is offline  
Old 12th Mar 2019, 23:15
  #870 (permalink)  
 
Join Date: Jul 2013
Location: In a Pineapple Under the Sea
Age: 58
Posts: 101
Originally Posted by FCeng84 View Post
Hans - your patience is amazing. You are correct about the relationship between 737MAX engines and need for MCAS. It has nothing to do with the thrust pitching moment!!!

There is a cert requirement that as AOA increases, the nose up pilot command required must not decrease. This is demonstrated at fixed thrust levels so there is no change in thrust pitching moment. The 737MAX issue here that gives rise to the need for MCAS is that as AOA increases the lift provided by the engine cowling that is so large and mounted so far forward of the wing causes a nose up pitching moment that results is a decrease in the column pull needed to maintain a steady positive AOA rate. That characteristic is not compliant with the requirements. MCAS comes active during this maneuver putting in nose down stabilizer that must be countered by the column. The net effect of engine cowling lift and MCAS nose down stabilizer as AOA increases is that the column needed to complete the maneuver does not decrease part way through the range of AOA for which characteristics must be demonstrated. 737MAX without MCAS fails the cert demo. 737MAX with MCAS passes the cert demo.
That is a very clear explanation - the most clear of anything I've read. Well done FCeng84.

What is interesting, then, is that MCAS activates without column input. If the purpose of MCAS is to essentially negate the lift of the engine cowling - which causes lift when AOA increases - then one would think the system would only activate as a result of column pull. In other words - the system is to create a consistent feel on the column - so why have it activate absent deliberate pull on the column? Why doesn't the system require both an increase in AOA and a pull on the column before it trims AND?
WillFlyForCheese is offline  
Old 12th Mar 2019, 23:21
  #871 (permalink)  
 
Join Date: Sep 2008
Location: Been around the block
Posts: 588
The new Boeing is NOT the same as “old” Boeing. Old Boeing was an engineering company that built solid, reliable aircraft. Everything was done in house by American. New Boeing are bean counters and exporters of the cheapest widget to put between parts A and B. Think of old Boeing as Toyota. Engineering tells accounting what they need. Accounting figures how to make it work. New Boeing is accounting telling engineering what they need. They’re really not even the same company. The only similarities are that they both make airplanes. A perfect example. Boeing has representatives that accompany new aircraft orders. This people used to be liaisons that would smooth things over between mx, finance, safety, training and even sales. They had a company credit card and a lot of freedom and leeway. These same individuals now have their dinner receipts audited by an accountant to make sure that they didn’t order steak or lobster. Boeing has become a good barometer of Merika. No leadership, petty micromanaging and mediocrity.
4runner is offline  
Old 12th Mar 2019, 23:24
  #872 (permalink)  
 
Join Date: May 2000
Location: London, UK
Posts: 364
It seems the issue is not so much with MCAS as with the engine location relative to the wing.

MCAS reads like a half baked solution to a problem that should not be there in the first place.

If so, this is not the kind of design philosophy I associate with Boeing.

Diverting aircraft in the cruise because they have a problem taking off doesn’t sound like a terribly rational response either.
SLF3 is offline  
Old 12th Mar 2019, 23:30
  #873 (permalink)  
 
Join Date: Feb 2009
Location: Seattle
Posts: 379
737 Pitch Trim Related Switches

There seems to be some confusion with regard to 737 switches associated with pitch trim. That is very understandable as there are quite a few and it is easy to get them mixed up. Let me take a run at an overview:

Wheel mounted pilot electric pitch trim switches - two pairs of side-by-side switches with one pair mounted on each of the two control wheels for thumb activation
- Spring centered with contacts in both the fwd/push and aft/pull directions.
- Fwd/push commands airplane nose down stabilizer motion via electric stab trim motor
- Aft/pull commands airplane nose up stabilizer motion via electric stab trim motor
- Stabilizer motion requires activation of both switches found on the same wheel in the same direction. This design avoids unintended stabilizer motion for a failure of one switch or a short in one of the two associated wiring circuits.

Column cutout switches - one each in push and pull directions
- Not visible to the crew, hidden within the column mechanism
- One is activated for column push beyond a certain threshold, the other for column pull beyond a certain threshold
- These prevent pilot electric pitch trim in the direction opposite the column (nose up trim inhibited when column is pushed for example)
- These also serve to stop STS stabilizer commands in the direction opposite the column
- These do not stop MCAS stabilizer commands in either direction

Column cutout override switch (not sure of the location(s) or how many there are)
- When in the override position, this causes the column cutout switches to be bypassed allowing electric stabilizer trim in either direction regardless of column position
- These do not have any role with respect to normal operation
- These have no function with respect to MCAS as MCAS stabilizer commands are not subject to the column cutout functionality that is overridden here

Stabilizer cutout switches - on pair of guarded switches located on the lower, aft end of the aislestand
- These are the switches that when activated remove electric power to the stabilizer trim motor and thus disable all electric trim (pilot wheel switches, STS, MCAS, autopilot offload)
- These are the switches that have been most discussed in this thread
- These are the switches that the runaway stabilizer procedure calls for toggling to stop errant stab motion

I hope this helps.

Last edited by FCeng84; 13th Mar 2019 at 03:49. Reason: formatting for easier reading
FCeng84 is offline  
Old 12th Mar 2019, 23:37
  #874 (permalink)  
 
Join Date: Oct 2011
Location: Lower Skunk Cabbageland, WA
Age: 70
Posts: 354
Originally Posted by 4runner View Post
The new Boeing is NOT the same as “old” Boeing. Old Boeing was an engineering company that built solid, reliable aircraft. Everything was done in house by American. New Boeing are bean counters and exporters of the cheapest widget to put between parts A and B. Think of old Boeing as Toyota. Engineering tells accounting what they need. Accounting figures how to make it work. New Boeing is accounting telling engineering what they need. They’re really not even the same company. The only similarities are that they both make airplanes. A perfect example. Boeing has representatives that accompany new aircraft orders. This people used to be liaisons that would smooth things over between mx, finance, safety, training and even sales. They had a company credit card and a lot of freedom and leeway. These same individuals now have their dinner receipts audited by an accountant to make sure that they didn’t order steak or lobster. Boeing has become a good barometer of Merika. No leadership, petty micromanaging and mediocrity.
Yes, and this happened when they acquired McDonnell-Douglas and brought-in most of MD's executives to run things.
Organfreak is offline  
Old 12th Mar 2019, 23:38
  #875 (permalink)  
 
Join Date: Feb 2009
Location: Seattle
Posts: 379
Originally Posted by WillFlyForCheese View Post
That is a very clear explanation - the most clear of anything I've read. Well done FCeng84.

What is interesting, then, is that MCAS activates without column input. If the purpose of MCAS is to essentially negate the lift of the engine cowling - which causes lift when AOA increases - then one would think the system would only activate as a result of column pull. In other words - the system is to create a consistent feel on the column - so why have it activate absent deliberate pull on the column? Why doesn't the system require both an increase in AOA and a pull on the column before it trims AND?
I'm glad to be able to provide some clarity. MCAS operates as a function of AOA with no regard to column position. As you state, "MCAS is to essentially negate lift (more specifically pitching moment) of the engine cowling". By cancelling out the nose up pitching moment from the cowling with increased AOA, MCAS smooths out the overall Cm-alpha (pitching moment vs. AOA) characteristic of the airplane so that column required to command a maneuver to high AOA does not decrease along the way.
FCeng84 is offline  
Old 12th Mar 2019, 23:43
  #876 (permalink)  
 
Join Date: Nov 2010
Location: Denver
Age: 52
Posts: 70
Originally Posted by Luc Lion View Post
That's also my understanding : "control column actuated trim cutout switches" have no effect on MCAS while the "stabilizer trim cutout switches" on the control stand do stop MCAS.
(I understand that it's the AUTOPILOT Cutout switch that does the job).
But I am not a B737 pilot, so I am happy to stand corrected.
There is no control column cutout switches, but the trim control on the control column will stop and override MCAS for 5 sec. There are trim cutout switches on the pedestal that stop MCAS permanently.
hans brinker is offline  
Old 12th Mar 2019, 23:45
  #877 (permalink)  
 
Join Date: Jul 2013
Location: In a Pineapple Under the Sea
Age: 58
Posts: 101
Originally Posted by FCeng84 View Post
I'm glad to be able to provide some clarity. MCAS operates as a function of AOA with no regard to column position. As you state, "MCAS is to essentially negate lift (more specifically pitching moment) of the engine cowling". By cancelling out the nose up pitching moment from the cowling with increased AOA, MCAS smooths out the overall Cm-alpha (pitching moment vs. AOA) characteristic of the airplane so that column required to command a maneuver to high AOA does not decrease along the way.
Understood. But if the (sole?) purpose is to "smooth out of the overall Cm-alpha characteristic of the airplane so that column required to command a maneuver to high AOA does not decrease along the way", then why does it trim AND with no column input at all? It appears to be a design to have the primary (or only?) effect of mimicking a condition on the column. if so - why have it operate in the absence of a pull on the column?

WillFlyForCheese is offline  
Old 12th Mar 2019, 23:47
  #878 (permalink)  
 
Join Date: Oct 2007
Location: A better place.
Posts: 1,713
Kiwis become the latest to suspend the Max - affecting a small number of Fiji Airways flights.
Interesting to observe the rest of the world effectively ignoring the FAA - perception versus known facts.
What a monumental debacle for Boeing.
tartare is offline  
Old 12th Mar 2019, 23:50
  #879 (permalink)  
 
Join Date: Jun 2001
Location: Rockytop, Tennessee, USA
Posts: 5,816
Originally Posted by Luc Lion View Post
Airbubba, the "control column actuated trim cutout switches" are switches located in the control column that stop an electric trim movement when the control column requests an elevator deflection contradicting the trim movement. This is the immediate response to a stuck electric trim button before using the STAB TRIM MAIN ELECT cutout switch on the control stand.
Thanks, seems like there was something like that on the 727.

Originally Posted by FCeng84 View Post
There seems to be some confusion with regard to 737 switches associated with pitch trim. That is very understandable as there are quite a few and it is easy to get them mixed up. Let me take a run at an overview:

I hope this helps.
It does, thanks!
Airbubba is online now  
Old 12th Mar 2019, 23:56
  #880 (permalink)  
 
Join Date: Mar 2006
Location: Vance, Belgium
Age: 58
Posts: 181
Originally Posted by hans brinker View Post
There is no control column cutout switches, ....
There are such switches, although they are hidden in the column.
See FCOM 9.20 "Controls - System Description" - "Stabilizer Trim".
Read also the function of the "Stabilizer Trim Override Switch"
Luc Lion is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.