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Ethiopian 737 Max 8 crash and Fallout

straitman

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From Aviation Week & Space Technology.

Wiring Fixes Among Changes FAA Will Require Before MAX Can Return
Sean Broderick August 03, 2020

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Credit: Boeing


WASHINGTON—The FAA’s proposed steps for operators to clear Boeing 737 MAXs for service include separating wire bundles deemed to be noncompliant with regulations and conducting “readiness” flights to ensure the long-grounded aircraft are airworthy, a draft notice of proposed rulemaking (NPRM) made public Aug. 3 reveals.

The wire-bundle issue, discovered during regulators’ comprehensive review of the MAX’s design and certification, concerns horizontal stabilizer trim arm and control wiring that runs the length of the aircraft. The FAA found that the wiring needs to be separated in 12 places to meet 2007 regulatory changes put in place to prevent wiring failures from creating hazards.

The agency ordered Boeing to fix the issue on new-production MAXs and develop instructions for in-service aircraft.

Many MAX operators planned to take advantage of the ongoing grounding and make the wiring changes before returning their MAXs to revenue flying, using service instructions Boeing issued on June 10. What was not clear: whether the FAA would require operators to address the issue before the MAXs flew again or give them the flexibility of a longer window for compliance, which is typical for many airworthiness directives. The NPRM confirms that the wiring work is one of several steps that must be completed on each existing MAX before returning to revenue service.

Because Boeing made the in-service modification work package available nearly two months ago and the FAA tentatively approved its contents, the agency’s wiring mandate is not expected to add time to MAX return-to-service preparation.

Updating MAX wiring, while an important regulatory compliance issue, is an ancillary change in the package of upgrades that will end what will likely be an 18-month-plus fleet grounding. The major changes are installing updated flight control computer (FCC) software that modifies the MAX’s maneuvering characteristics augmentation system (MCAS); new “MAX Display System” software that gives pilots more information on anomalies; and putting pilots through new, updated training.
 

straitman

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From World of Aviation.

FAA REVEALS PROPOSED CHANGES FOR 737 MAX
written by Hannah Dowling August 4, 2020

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In a new airworthiness direction (AD) dated 3 August, the US Federal Aviation Administration revealed its proposed design changes for the troubled Boeing 737 MAX.

The proposal aims to address the issues raised by the aircraft’s manoeuvring characteristics augmentation system (MCAS), which appeared to be at the heart of two fatal 737 MAX crashes in 2018 and 2019.

As such, the FAA has proposed four key changes to the aircraft, after previously determining that “final corrective action is necessary to address the unsafe condition” of the aircraft.

This first proposed design change is the installation of an entirely new flight control computer (FCC) software, with new control laws.

“These revised flight control laws would use inputs from both AOA sensors to activate MCAS,” the FAA noted.

This is in contrast to the original MCAS design, which relied on data from only one sensor at a time, and allowed repeated MCAS activation as a result of input from a single AOA sensor.

The new FCC and revised control laws are intended to prevent the “erroneous MCAS activation”, and ultimately give the pilots better control over the airplane pitch, an ability that was inhibited under the original MCAS design.

The second design change is the installation of new MAX display system (MDS) software, which essentially works to alert the flight crew should there be an error in one of the two AOA sensors.

The new display will have the capacity to create a visual alert on the airplane’s primary flight display (PFD), which informs the flight crew if there is a disagreement between the angles of attack measured by each of the plane’s two AOA sensors.

The third design change proposed by the FAA is to revise the existing Airplane Flight Manual (AFM), in order to appropriately incorporate new and revised flight crew operating procedures.

This change hopes to ensure that the flight crew have the means to recognise and respond to erroneous stabiliser movement and the effects of a potential AOA sensor failure.

A previous criticism of the 737 MAX was the flight crew were not appropriately trained or informed of the operating procedures under the new operating system.

The fourth proposed change is to change the routing of horizontal stabiliser trim wires, in order to restore compliance with the FAA’s latest wire separation safety standards.
 

jenib

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This seems like a very shallow article that gives little information and incorrect perspective. There is a lot more articles out there that explain things a whole lot better.
Thanks for the (perceived to be rude) response. I don't really see what is incorrect about the perspective but each to their own. Perhaps you are a Boeing tragic. I used to be and I am just a flyer not a pilot or an airplane engineer but I was a software engineer and I have read many articles about what went wrong. From a software perspective there was a LOT that went wrong - most importantly lack of redundancy which I was taught was criminal in life threatening circumstances.
 
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ja1

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Why doesn't Boeing just start their own airline with the 450 death traps no one really wants?

Wonder how many people would fly them ;)
They wouldn't have any engines.. remember, boeing builds airframes.. :)

So they'd probably a hell of a lot safer as they'd stay on the ground..
 
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straitman

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Thanks for the (perceived to be rude) response. I don't really see what is incorrect about the perspective but each to their own. Perhaps you are a Boeing tragic. I used to be and I am just a flyer not a pilot or an airplane engineer but I was a software engineer and I have read many articles about what went wrong. From a software perspective there was a LOT that went wrong - most importantly lack of redundancy which I was taught was criminal in life threatening circumstances.
I am not sure why or how you see my response as rude as all I did was offer my opinion on the FT article. The article states that ‘the agency is requesting changes to both the flight control computer and the MAX display system.’

In reality this is what the AD and associated NPRM states: 'This proposed AD would require installing new flight control computer (FCC) software, revising the existing Airplane Flight Manual (AFM) to incorporate new and revised flight crew procedures, installing new MAX display system (MDS) software, changing the horizontal stabilizer trim wire routing installations, completing an angle of attack sensor system test, and performing an operational readiness flight. This proposed AD would also apply to a narrower set of airplanes than the superseded AD, and allow operation (dispatch) of an airplane with certain inoperative systems only if certain provisions are incorporated in the operator’s existing FAA-approved minimum equipment list (MEL).'

I.e. it is a lot more complex that indicated in the FT article.

Am I a Boeing tragic? Hardly, though I have been around aviation at many levels for more than 50 years and have been near and around many aircraft accidents and have been involved in accident investigation more times than I care to discuss. One of the more memorable was being first on the scene of the RAAF 707 accident off Woodside Beach in October 1991.
 
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Franky

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I am not sure why or how you see my response as rude as all I did was offer my opinion on the FT article. The article states that ‘the agency is requesting changes to both the flight control computer and the MAX display system.’

In reality this is what the AD and associated NPRM states: 'This proposed AD would require installing new flight control computer (FCC) software, revising the existing Airplane Flight Manual (AFM) to incorporate new and revised flight crew procedures, installing new MAX display system (MDS) software, changing the horizontal stabilizer trim wire routing installations, completing an angle of attack sensor system test, and performing an operational readiness flight. This proposed AD would also apply to a narrower set of airplanes than the superseded AD, and allow operation (dispatch) of an airplane with certain inoperative systems only if certain provisions are incorporated in the operator’s existing FAA-approved minimum equipment list (MEL).'

I.e. it is a lot more complex that indicated in the FT article.

Am I a Boeing tragic? Hardly, though I have been around aviation at many levels for more than 50 years and have been near and around many aircraft accidents and have been involved in accident investigation more times than I care to discuss. One of the more memorable was being first on the scene of the RAAF 707 crash off Woodside Beach in October 1991.
Straitman - glad to see you have cleared that up, however I must say that I also thought your initial comment was a bit abrupt.
 

jenib

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I am not sure why or how you see my response as rude as all I did was offer my opinion on the FT article. The article states that ‘the agency is requesting changes to both the flight control computer and the MAX display system.’

In reality this is what the AD and associated NPRM states: 'This proposed AD would require installing new flight control computer (FCC) software, revising the existing Airplane Flight Manual (AFM) to incorporate new and revised flight crew procedures, installing new MAX display system (MDS) software, changing the horizontal stabilizer trim wire routing installations, completing an angle of attack sensor system test, and performing an operational readiness flight. This proposed AD would also apply to a narrower set of airplanes than the superseded AD, and allow operation (dispatch) of an airplane with certain inoperative systems only if certain provisions are incorporated in the operator’s existing FAA-approved minimum equipment list (MEL).'

I.e. it is a lot more complex that indicated in the FT article.

Am I a Boeing tragic? Hardly, though I have been around aviation at many levels for more than 50 years and have been near and around many aircraft accidents and have been involved in accident investigation more times than I care to discuss. One of the more memorable was being first on the scene of the RAAF 707 accident off Woodside Beach in October 1991.
OK. Not everyone on these boards has the time, inclination or expertise to read detailed articles with all of the complexities involved which is why I posted the article. Also, different people have different expertise and perspectives. Everyone is a bit unsettled by the current situation - particularly those interested in or invested in aviation. I see the same things happening in the cruising industry.

I do think (from my experience) that Boeing has a lot to answer for - not the engineers but the management who allowed this to happen in the interest of profit or by employing incompetent people or subcontractors and not training them appropriately. I also worry about what that means for the aviation industry in the future (when there is a future).
 

jb747

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Very cunning. It will be difficult for people to see a difference between 738, 737-800 and 737-8 when booking flights.
In that case just pick an airline that uses the A320 family.

For the life of me though, I cannot see why Boeing has not reactivated/installed a system that existed on all of their previous aircraft. In (for instance) the 767, if you had a trim runaway, moving the control column in the opposite direction (which is the natural reaction anyway) would stop it. The lack of this particular safety step, is what makes me think the MCAS was not there for stall prevention, but rather, to fix otherwise unacceptable aerodynamics. At the end of all of this, any aerodynamic issues will still remain.
 

AviatorInsight

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Maybe it will only be the name Max that goes.
Boeing we’re using the -8 version to distinguish the different types in the flight manuals when it first came out. We thought it was also a bit confusing as we just thought it was for the -800 but clarification from Boeing themselves revealed that the -8 is in fact the Max8.

I always thought it was weird that they never specified anywhere in the manual that -8 really meant MAX.
 

AviatorInsight

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In that case just pick an airline that uses the A320 family.

For the life of me though, I cannot see why Boeing has not reactivated/installed a system that existed on all of their previous aircraft. In (for instance) the 767, if you had a trim runaway, moving the control column in the opposite direction (which is the natural reaction anyway) would stop it. The lack of this particular safety step, is what makes me think the MCAS was not there for stall prevention, but rather, to fix otherwise unacceptable aerodynamics. At the end of all of this, any aerodynamic issues will still remain.
That same tactic works on the NG too! Also if you activated the trim wheel in the opposite direction it would also stop the runaway.

The last sim I had back in January we did trim runaway, once I identified it was a runaway I held the control column, and just pushed and held down the trim in the opposite direction until the PM could get to the switches and turn them off.

Why Boeing then had to go and screw with the system is beyond me.
 

drron

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It looks like the Europeans who will be first to allow the 737 MAX back into the skies.


"Patrick Ky, Executive Director of the European Union Aviation Safety Agency (EASA) has today stated that he’s satisfied with the changes that Boeing has made to the 737 MAX.


This is a major milestone, but even so, the 737 MAX won’t be able to return to the European skies immediately:


  • The EASA is currently performing final document reviews
  • Then a draft airworthiness is expected to be issued next month
  • That will be followed by a four week period for public comment
  • At that point the plane will be able to once again enter commercial service in Europe, which is expected to happen before the end of the year"
 

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