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MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures

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MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures

Old 10th Sep 2019, 17:03
  #2281 (permalink)  
 
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Originally Posted by cappt View Post
Putting it through a complete flight test program could take a year or more realistically. Euro airlines should be looking for alternative aircraft.
A one week flight test program is mentioned.

The last slide in the document contains:-

Flight tests on a modified B737 max [one full week - at Boeing Flight Test Center]
- MCAS operations (nominal behavior)
- Flight without MCAS (including high speed turns and stall)
- Scenario of stabiliser runaway (uncommanded MCAS activation, manual trim wheel forces)
- Approach to stall with autopilot engaged

Last edited by jimjim1; 10th Sep 2019 at 17:19.
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Old 10th Sep 2019, 17:10
  #2282 (permalink)  
 
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Originally Posted by jimjim1 View Post
Presentation to European Parliament by the Executive Director of EASA
3 Sept 2019
A LOT of attention on the MAX.

https://www.europarl.europa.eu/cmsda...y-original.pdf
Here is the video of the presentation,

https://www.europarl.europa.eu/ep-li...COMMITTEE-TRAN
Press play icon on video

Mr Ky speaks as follows

10:26 Mr Ky General topics
10:35:11 737 MAX
10:46:19 End of Mr Ky presentation
Questions by Members

11:28:24 Responses by Mr Ky
11:57 Additional questions and responses and chair comments
12:02 End

I made some headline notes through the video - No idea if they will interest anyone but electrons are quite cheap.

# # # # # # # #

10:25 CHAIR
Introduction

10:26 Mr Ky
Think Mr Ky spoke in English. Some speakers are simultaneously translated.

10:35:11 737 MAX

10:46:19 End of Mr Ky presentation

Questions/Comments from Members

10:52:35
BREXIT
FAA
Relationship with FAA



Ricardo report - posting of workers, bogus self employed, use of 3rd world,
use of secondment

Flight time limitations

Maybe something earlier too - 737 MAX flight paths?

BREXIT

Green air travel - biofuels

Cyber security

Drones (Gatwick, frankfurt disruption

Smartwings - one engine

Green air travel

MAX earlier pilot indications - pilot experience

MAX FAA delegation, does EASA do it too? does China do it.

Cyber security

Social dimension - bogus self employed, precarious unstable work, not to be a
danger to flight?

Green air travel - ultra fine particles and human health

A330neo - poor cabin air

Electric aircraft - green approach

Drones - international agreements, noise (other countries have air taxis:-)

11:21

Passenger behaviour

CHAIR
3% of global emissions (guess CO2) - not reducing emissions
What is the alternative to fossil fuels?
"Positive Fuels"
How did you calculate carbon footprint for Eco label.
Pilot stress (unspoken reference to european airline pilot suicide)
BREXIT (Spain)
Digitalisation objective
Drones (licencing), flying taxis

11:28:24
Responses by Mr Ky

BREXIT

11:33 FAA

737 MAX International report in next week on What went wrong vis a vis
FAA/Boeing.

EASA doesn't delegate so freely - more structured

FAA relationship in the future

Social re- safety

Green

Supersonic MUST be quieter than existing aircraft on take-off
5 SST projects in progress in USA

Drones - Google wings has been delivering parcels for last two years in
Canberra - noise complaints

Cyber

A330neo cabin air

Smartwings single engine - says ok. crew get to decide suitable airport

11:55 MAX No timeline for return to service

FAA

11:57 /Ky

More questions from Committee

Brexit
Pilot fatigue

Mr Patrick Ky re-response

Brexit
Pilot fatigue

12:01

Chair
Social

12:03 END




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Old 10th Sep 2019, 17:12
  #2283 (permalink)  
 
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Originally Posted by OldnGrounded View Post
The link is to a paywalled site and not everyone here is a subscriber to that periodical. So, if you want that article to be discussed, please summarize the relevant points.
It requires registration - but access is free - I've just done it without difficulty.
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Old 10th Sep 2019, 17:30
  #2284 (permalink)  
 
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Great job Jimjim1 !

Thanks for that
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Old 10th Sep 2019, 17:31
  #2285 (permalink)  
 
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Some EASA slides re MAX return to service: European Parliament

Originally Posted by jimjim1 View Post
Presentation to European Parliament by the Executive Director of EASA
3 Sept 2019
A LOT of attention on the MAX.
https://www.europarl.europa.eu/cmsda...y-original.pdf
Here are pages 11-16 for your convenience. Fancy slides all gone, raw text all here, nearly.

Return to Service - EASA conditions p 11

Letter sent to the FAA on April 01, 2019.

4 conditions:

1. Design changes proposed by Boeing are EASA approved (no delegation to
FAA)
2. Additional and broader independent design review has been satisfactorily
completed by EASA
3. Accidents of JT610 and ET302 are deemed sufficiently understood
4. B737 MAX flight crews have been adequately trained


EASA design review p 12

Objective: to ensure that no similar weaknesses in the design are present in
the other (safety critical) areas of the 737 MAX design.
Activities are being carried out on the Flight Control System and all
associated functions/systems including but not limited to the following:
displays, alerting system, autopilot and air data system.

- Review of Functional Hazard Assessments and Safety Analysis
- Review of Development Assurance process
- Review of Flight Controls and Autopilot architecture and logics
- Review of Human Factors aspects
- Review of the methodology applied for the assessment of the Crew Training
needs


EASA activities p 13

EASA PROPRIETARY – Do not disclose without EASA consent
- Unprecedented level of effort, involving around 20 multi-disciplinary
experts, including test pilots and engineers, 2-3 weekly web- based meetings
with Boeing, review of 500+ documents and actions
- EASA requirements for flight/Simulator evaluation communicated on May 22.
70 test points requested to be evaluated, covering:
- Normal operations (identification of MCAS operation)
- Abnormal operations (AoA failures, stabiliser runaway, MCAS inoperative,…)
- Simulators evaluation performed in June and July.

EASA findings p 14

Significant technical issues:

- Lack of exhaustive monitoring of the system failures resulting in a
stabiliser runaway
- Too high forces needed to move the manual trim wheel in case of a
stabiliser runaway
- Too late disconnection of autopilot near stall speed (in specific
conditions)
- Too high crew workload and risk of crew confusion in some failure cases,
especially Angle of Attack single failure at take-off

Findings communicated to Boeing and FAA in July 2019

p 15 in image below



Next major milestones p 16

EASA PROPRIETARY – Do not disclose without EASA consent
- Safety assessment of the new design changes proposed by Boeing, including
operational procedures
- Human factor evaluation and functional tests of the new software
- Flight tests on a modified B737 max [one full week - at Boeing Flight Test Center]
-- MCAS operations (nominal behavior)
-- Flight without MCAS (including high speed turns and stall)
-- Scenario of stabiliser runaway (uncommanded MCAS activation, manual trim wheel forces)
-- Approach to stall with autopilot engaged
- Crew Training requirements, in particular using Computer Based Training or Simulator
- Coordination with EASA Member States on Return to Service actions


Flight tests on a modified B737 max [one full week - at Boeing Flight Test Center]
- MCAS operations (nominal behavior)
- Flight without MCAS (including high speed turns and stall)
- Scenario of stabiliser runaway (uncommanded MCAS activation, manual trim wheel forces)
- Approach to stall with autopilot engaged
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Old 10th Sep 2019, 20:31
  #2286 (permalink)  
 
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Originally Posted by jimjim1 View Post

A one week flight test program is mentioned.
Surely there are two distinct types of flight tests needed.

The first would be technical flights to assess things like aerodynamic stability without MCAS engaged and yes these should be carried out by professional test pilots. But the other flight testing is that which needs to be done to ascertain what level of training will be required for new MAX pilots on the modified model. This will require line pilots and preferably those who are 737 rated but with no experience on the MAX. After all, these will be the bulk of the pilots who will end up flying the MAXs parked at Renton and elsewhere.
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Old 10th Sep 2019, 21:11
  #2287 (permalink)  
 
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Originally Posted by Speed of Sound View Post

(...) But the other flight testing is that which needs to be done to ascertain what level of training will be required for new MAX pilots on the modified model. This will require line pilots and preferably those who are 737 rated but with no experience on the MAX.
any volunteers?
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Old 10th Sep 2019, 23:07
  #2288 (permalink)  
 
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Originally Posted by jimjim1 View Post

Flight tests on a modified B737 max [one full week - at Boeing Flight Test Center]
- MCAS operations (nominal behavior)
- Flight without MCAS (including high speed turns and stall)
- Scenario of stabiliser runaway (uncommanded MCAS activation, manual trim wheel forces)
- Approach to stall with autopilot engaged
The answers to some of these might be obvious, but I thought I'd ask anyway . . .

It's not clear what "uncommanded MCAS activation" means. Do they mean MCAS is activated even when the FCC is receiving consistent AoA values below the activation threshold? If so, how do they do this in a flight test? Are they going to fly an airplane with intentionally corrupted memory, which is what they apparently simulated in the EASA-requested simulator scenarios in July?

Why does the uncommanded MCAS activation scenario involve "manual trim wheel forces"? By now, every 737 pilot in the world must know (even if they didn't know after the Emergency AD) that the correct response to an incorrect MCAS activation is to fully neutralize control forces using MET and THEN place the switch in the CUT-OUT position. Doesn't requiring demonstration of the manual trim wheel as a re-certification requirement rely on the assumption that pilots still cannot be relied upon to perform this procedure and will still CUT-OUT electric trim with the airplane in an out-of-trim condition?

What is the regulatory basis for demonstrating recovery with a manual trim wheel when the published recovery procedure is to use MET before CUT-OUT? Obviously, fully FBW systems don't have a manual wheel and rely entirely on electronic controls to recover from a FCC-induced runaway trim condition. Why is the use of MET in the 737 different?

We know, based on the ET302 accident, that the manual trim wheel cannot be used to re-trim from certain trim positions beyond certain airspeeds. Presumably, EASA re-certification is going to require successful use of the manual trim wheel up to some lesser degree of out-of-trim/airspeed condition. Is there a regulatory basis for deciding what that condition must be?

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Old 10th Sep 2019, 23:24
  #2289 (permalink)  
 
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Originally Posted by Notanatp View Post
Doesn't requiring demonstration of the manual trim wheel as a re-certification requirement rely on the assumption that pilots still cannot be relied upon to perform this procedure and will still CUT-OUT electric trim with the airplane in an out-of-trim condition?
Perform a procedure is one thing.
Now how does a crew discover that the trim is misbehaving, requiring this specific procedure ? How long has a crew before things get out of hands ? Is the 737 MAX certifiable in this respect ? To date Boeing doesn't seem to have come up with a satisfying answer.
In the eye of the EASA, at least.
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Old 10th Sep 2019, 23:30
  #2290 (permalink)  
 
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Originally Posted by Notanatp View Post
By now, every 737 pilot in the world must know (even if they didn't know after the Emergency AD) that the correct response to an incorrect MCAS activation is to fully neutralize control forces using MET and THEN place the switch in the CUT-OUT position. Doesn't requiring demonstration of the manual trim wheel as a re-certification requirement rely on the assumption that pilots still cannot be relied upon to perform this procedure and will still CUT-OUT electric trim with the airplane in an out-of-trim condition?
No, it's simply conforming to the provisions of the AD:

Disengage autopilot and control airplane pitch attitude with control column and main electric trim as required. If relaxing the column causes the trim to move, set stabilizer trim switches to CUTOUT. If runaway continues, hold the stabilizer trim wheel against rotation and trim the airplane manually.

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Old 11th Sep 2019, 00:18
  #2291 (permalink)  
 
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Originally Posted by OldnGrounded View Post
The link is to a paywalled site and not everyone here is a subscriber to that periodical. So, if you want that article to be discussed, please summarize the relevant points.
Subscriptions are free

https://www.flightglobal.com/news/ar...llenge-460726/
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Old 11th Sep 2019, 00:30
  #2292 (permalink)  
 
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Originally Posted by DaveReidUK View Post
No, it's simply conforming to the provisions of the AD:
>Disengage autopilot and control airplane pitch attitude with control column and main electric trim as required.
>If relaxing the column causes the trim to move, set stabilizer trim switches to CUTOUT.
>If runaway continues, hold the stabilizer trim wheel against rotation and trim the airplane manually.

Surely that's not strictly correct?
As the switches on the control column have no effect on MCAS "trim", the condition "If relaxing the column causes the trim to move," is never satisfied.
So the AD doesn't actually specify "set stabilizer trim switches to CUTOUT" for an unintended MCAS activation.

So the second line of the AD should have read something like:
>If relaxing the column causes the trim to move - or if this is an inappropriate MCAS activation - set stabilizer trim switches to CUTOUT.

Or maybe a negative form would have been better:
>If the trim keeps running irrespective of control column input - set stabilizer trim switches to CUTOUT.
... but this would this have handled appropriate MCAS activation?
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Old 11th Sep 2019, 01:21
  #2293 (permalink)  
 
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The AD procedure was a revision to the runaway trim procedure. The first paragraph just repeats the original trim runaway procedure. The rest of the AD procedure addresses the erroneous AOA scenario. To me, the worst mistake in that AD procedure is the second to last sentence, which, instead of saying "Electric stabilizer trim can be used to neutralize the control column pitch forces" before using the cutout switches, should have said something like "You must use the electric stabilizer trim to neutralize the control column pitch forces before using the CUTOUT switches because the manual trim system will not work if the airplane is significantly out of trim." The Ethiopian crew seemed to figure that out well into the event and switched the electric trim back on, but too late to recover.

Last edited by Dave Therhino; 11th Sep 2019 at 01:44. Reason: clarity
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Old 11th Sep 2019, 01:49
  #2294 (permalink)  
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Can I just get confirmation of these points.

Electric trim switches. Electric thumb switches trim wins over MCAS
Hidden column-force switches. MCAS wins.

Ethiopian captain was trimming 'successfully' - it was on handover to his First Officer that the problem finally got out of hand.

Relaxing column forces. The prime problem is the delay before MCAS inputs again. Those five seconds lead to misinterpretation of the trim wheels' renewed cranking.
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Old 11th Sep 2019, 02:13
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If the pilot moves the trim switches on the column, that interrupts/overrides the MCAS commands and the pilots commands are followed by the trim system. MCAS resets and will fire again if more than 5 seconds have passed since the column switches were released and its triggering logic is satisfied.

When MCAS is activated, the column cutout switches are bypassed. This enables MCAS to change the trim in the direction opposite the column input from the pilot based on the presumption that the pilot is approaching a turning stalled condition.
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Old 11th Sep 2019, 03:27
  #2296 (permalink)  
 
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Originally Posted by Loose rivets View Post
Ethiopian captain was trimming 'successfully' - it was on handover to his First Officer that the problem finally got out of hand.
Actually that's probably what happened to the Lion Air accident flight, not to the Ethiopian flight. There was not much trimming done on the Ethiopian flight, but on the Lion Air accident flight they did a lot of trimming while fighting MCAS. And the control column forces recorded by the DFDR seem to indicate that the Lion Air captain handed over control to the FO shortly before they lost control.
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Old 11th Sep 2019, 03:38
  #2297 (permalink)  
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Ah, thanks. I had a moment of doubt as I was writing, hence the request for confirmation. If I'd had any idea how many hours I'd be reading in, I'd have taken copious notes with a reference system.
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Old 11th Sep 2019, 11:54
  #2298 (permalink)  
 
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So, as I understand it to summerise the present situation could be:

1. The EASA will do their own certification (whatever time scale that takes to complete)
2. As of this instant, Boeing is still recruiting for the following positions (temp but full-time):

AVIATION MAINTENANCE TECHNICIAN & INSPECTOR

at Moses Lake to get these aircraft back in the air which means within the next couple of months(?)

Which looks to me like the FAA has diverged from the EASA and plans to certify the Max in North America.

Nothing else makes sense to me after reading the PowerPoint slides. Boeing and the FAA are in this together and as others have said a lot of jobs and prestige is invested in this model but also the whole Boeing/FAA partnership.

Correct me if I have got this wrong by all means.
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Old 11th Sep 2019, 12:17
  #2299 (permalink)  
 
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Originally Posted by Thistle42 View Post

Correct me if I have got this wrong by all means.
You have got it wrong.

There is no way in a million years that the MAX will be cleared to fly in North America and still be grounded in the rest of the world.

The recruitment of technicians was something Boeing had to do in advance of their stated aim of getting the Max back in the air in September/October. These technicians will most likely be kept on hold until a more realistic date for return to service.
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Old 11th Sep 2019, 12:17
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Sorry, late to the conversation...at this time is there any suggestion we are going to get a third AoA wired up?
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