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

[OldnGrounded]

Excellent narrative."In short, a full-authority envelope-protection system".Which could also be meant to mean "anti-stall system", which is why Boeing went out of their way to dispense with the anti-stall verbiage.

Yes, an excellent description. And, while there are still some who insist that MCAS is only about stick force gradient, it appears that they are now outnumbered, among those who have been paying close attention, by observers who are, at least, fairly skeptical.

Will the relevant bare-airframe test results be released, or will Boeing be able to convince the world and the courts that they are properly proprietary?

[568]

Yes, an excellent description. And, while there are still some who insist that MCAS is only about stick force gradient, it appears that they are now outnumbered, among those who have been paying close attention, by observers who are, at least, fairly skeptical.

Will the relevant bare-airframe test results be released, or will Boeing be able to convince the world and the courts that they are properly proprietary?Equally excellent narrative!MCAS really shared 2 common themes, IMHO;1) Stick force gradient at the lower end of the speed envelope.2) Monitoring AoA to ensure that excessive pitch wouldn't end up as a stall.Somewhere along the design phase and flight test, I believe that there must have been numerous discussions on "how best to implement MCAS" and satisfy part 25 requirements, without raising further objections, concerns and engineering issues.

[maxter]

It will be back in the air. Hopefully based on good engineering and testing to ensure Boeing can regain the significant lack of trust it has at present.

[Bend alot]

It will be back in the air. Hopefully based on good engineering and testing to ensure Boeing can regain the significant lack of trust it has at present.
There are several regulators and groups that are looking and want to look very deeply at the raw airframe data of the MAX.

This is partly because of Boeing's flexibility with the truth, it's incorrect risk classifications and failure to disclose information during original certification.

As the days and weeks flow on is seems very possible that Boeing did some Jedi Mind Tricking of it's own to obtain Grandfather rights.

If that turns out to be true, the MAX will not fly again, as it will need a new type certificate. If a new type certificate is required a new aircraft is required, as the MAX would not meet the current requirements.

The re-certification is no longer certain - The FAA must meet the standards for the other regulators expectations of them, no more buddy deals between Boeing and the FAA as the FAA have indicated.

[568]

There are several regulators and groups that are looking and want to look very deeply at the raw airframe data of the MAX.

This is partly because of Boeing's flexibility with the truth, it's incorrect risk classifications and failure to disclose information during original certification.

As the days and weeks flow on is seems very possible that Boeing did some Jedi Mind Tricking of it's own to obtain Grandfather rights.

If that turns out to be true, the MAX will not fly again, as it will need a new type certificate. If a new type certificate is required a aircraft is required, as the MAX would not meet the current requirements.

The re-certification is no longer certain - The FAA must meet the standards for the other regulators expectations of them, no more buddy deals between Boeing and the FAA as the FAA have indicated.Exactly on point. Boeing and the FAA are probably at this cross roads (behind closed doors and email).

[Lake1952]

It will be back in the air. Hopefully based on good engineering and testing to ensure Boeing can regain the significant lack of trust it has at present.

It has been grounded for almost 10 months. If software were the only problem, it would have been weeks, not months. Something more than just software, I am assuming

[edmundronald]

In a sim, not that long ago, in a trim runway scenario who went quit far, because it was really difficult for me to turn the wheel with one hand as Pilot monitoring, I told the PF (Who was pulling the yoke, plane was trimed nose down), that we should both have one hand on the yoke to pull and the other empty to trim, the 2 handle are always quit in "opposite" location on the 2 wheel, so I always understood it was designed like this, in some case to be used by the 2 pilots ... And guess what ! All worked really well and we were able to have the trim back in easy movable position ...

Flocks,

One of the discoveries when a magnifying glass was passed over the trim runaway training in light of some real-world incidents with the MAX is that it appears that BA "forgot" to implement correct force feedback on the trim wheels in the sims, including the NG. Due to the shrunk trim wheels implemented in the NG, the real forces required may be above what can be expected of some crews.

Another discovery is that BA has become bad at passing essential information to the pilot community.

Edmund

[xetroV]

Boeing plans to hand out "safety" cards to convince pax that Max is safe. (https://www.nytimes.com/2019/12/24/business/boeing-737-max-survey.html)
I thought the whole MAX saga was already a PR disaster of the highest order, but apparently there's always someone that can do worse. To think that some people actually held a meeting and decided that a 3-by-5-inch card would get the message across to the anxious traveller that the MAX is now really, really safe...

- "So what kind of jedi mind-trick would make the public trust our aircraft again?"
- "Well, you know, we could hand over a safety leaflet or something..."- "No, a leaflet won't grasp enough attention. We need something more substantial, say... a card!"
- "Brilliant idea! Let's hand over safety cards!"
- "So what size should we use? I was thinking something portable, like 3 x 4 inch?"
- "Meh, a bit small, ain't it? What about 4 x 4?"
- "No, too square. You know what - we'll settle for 3 x 5 inch"
- "Great, consider it done! One more problem solved then."


Un!be!lie!va!ble! :ooh:

[Stribeck]

I thought the whole MAX saga was already a PR disaster of the highest order, but apparently there's always someone that can do worse. To think that some people actually held a meeting and decided that a 3-by-5-inch card would get the message across to the anxious traveller that the MAX is now really, really safe...

- "So what kind of jedi mind-trick would make the public trust our aircraft again?"
- "Well, you know, we could hand over a safety leaflet or something..."- "No, a leaflet won't grasp enough attention. We need something more substantial, say... a card!"
- "Brilliant idea! Let's hand over safety cards!"
- "So what size should we use? I was thinking something portable, like 3 x 4 inch?"
- "Meh, a bit small, ain't it? What about 4 x 4?"
- "No, too square. You know what - we'll settle for 3 x 5 inch"
- "Great, consider it done! One more problem solved then."


Un!be!lie!va!ble! :ooh:

Impressive work by the PR department over the holidays!

Seems like they came up with a "Method to Continuously Aggravate the Situation", or MCAS:
Shoot yourself in the foot, repeat as necessary with 5 second intervals.

Not sure how it will help get the planes back in the sky, but at least it could trigger some golden parachutes.

[9 lives]

The FAA must meet the standards for the other regulators expectations of them

This is a very important theme. The world's other regulators work for their citizens. The citizens, both as passengers, and as taxpayers, employ the regulators to be the knowledgeable and objective intermediaries to assure the safety of the flying public. The regulators develop and then apply internationally accepted design and manufacturing standards. And, commonly, they accept each other's work via bilateral certification agreements. Not so much this time. The FAA has broken faith with the other regulators, and they are questioning the completeness of the FAA's certification process. The bilateral agreements allow any authority to independently "familiarize" themselves with the certification of another authority - for the re introduction of the MAX, they're doing it!

The citizens have every right to assert their demand for design compliant planes for their safe travel. They can do this by asking what type they're being booked on, and by demanding the independent evaluation of their national authority. Some national authorities, including the FAA, employ a system of delegation of certification activities to specified persons in the manufacturer's company. If the system works properly, the public's interests are well represented. If the manufacturer has too much influence over their delegated staff, there could be a problem. In the case of the MAX, there was a problem. The FAA would rather not admit it, but the other authorities see what's going on, and are going to check for themselves.

The FAA's and Boeing's desire for a schedule for this will be missed. Worse, would be the FAA tries to recertify the MAX before the other authorities do, that would look bad! And, worse when they realize that though that might enable the MAX to fly US domestic, it would not be accepted internationally, That would be embarrassing!

The FAA's miss on past certification activities on the MAX have been exposed to the world, and they have no choice but to be thorough and transparent in the recertification effort, and they and Boeing take their lumps in the process.

[LowObservable]

Can't it? Even not with enough lipstick and citing "alternate means of compliance" ?
I'm still guessing it all has been agreed on and they are just fighting about documention, training and other "formalities" . Everyone needs that plane back in the air - even the Chinese.

What EASA was saying during most of the fall was that the solution was a third AoA vane. Hopefully, Boeing has had a Team B working on exactly that, including a retrofit kit that can be installed in 15 minutes using a Leatherman and a Dremel.

[OldnGrounded]

What EASA was saying during most of the fall was that the solution was a third AoA vane. Hopefully, Boeing has had a Team B working on exactly that, including a retrofit kit that can be installed in 15 minutes using a Leatherman and a Dremel.

On the other hand, the information that has been shared* about what B is actually doing says that MCAS 2.0 will use only the two existing vanes, together with both FCCs operating simultaneously, and logic that disables MCAS (and perhaps other automatics) on disagreement. I don't think they're working on a third AoA sensor solution, although that, fairly obviously, would be the right thing to do if you were starting from a clean sheet for MCAS.

Of course, if you were actually starting from a clean sheet, it might be a good idea to design an airframe that didn't require MCAS.

* Boeing's Fix Tames the Tiger . . . (https://www.seattletimes.com/business/boeing-aerospace/boeings-fix-tames-the-tiger-in-the-737-max-flight-controls/)

[turbidus]

https://cimg7.ibsrv.net/gimg/pprune.org-vbulletin/278x194/pilots_copy_be8280b0ebf5a352950943a035ea6a31efc886f0.jpg
I thought the whole MAX saga was already a PR disaster of the highest order,

Yes, the 3x5 cards! I see in the presentation, that the cards were also to go to the pilots. Was this to make them feel more confident to fly the MAX? :rolleyes:

My thoughts are that the pilots should NOT be involved in this in any way, I can imagine some unintended consequences.

FAQ and Key Points cards for pilots???????? Is this instead of sim training????

This Boeing slide is what they should be very concerned about: TRUST

https://cimg7.ibsrv.net/gimg/pprune.org-vbulletin/505x124/ba_trust_copy_b50f26fb27b5bca46d49f07fa7ad8e06e1c05fe0.jpg

[LowObservable]

On the other hand, the information that has been shared* about what B is actually doing says that MCAS 2.0 will use only the two existing vanes, together with both FCCs operating simultaneously, and logic that disables MCAS (and perhaps other automatics) on disagreement.

That's what I call "pseudo-triplex". I don't think the international authorities are buying it.

[Grebe]

That's what I call "pseudo-triplex". I don't think the international authorities are buying it.

https://www.isasi.org/Documents/library/technical-papers/2011/Introducing-787.pdf

SEE Pages 39 to 42

787 Synthetic Airspeed

Introducing the 787 - Effect on Major Investigations - And Interesting Tidbits

Tom Dodt Chief Engineer – Air Safety Investigation ISASI September, 2011
+++

I would think a simple inertial compare re pitch angle ( eg floor angle ) and horizontal flight path would give an reasonably approximate AOA via a totally internal system- at least accurate enough to identify out of range or false compares of two external AOAS sensors.

After all- Boeing must use a similar internal - inertial compare to their military orbital spaceplane which stays up for a year or more and then lands automatically. Reentry no doubt does not alllow external vane type sensors , etc.

[GlobalNav]

That's what I call "pseudo-triplex". I don't think the international authorities are buying it.

Perhaps I misunderstand your meaning, but I think triplex architecture provides for continued function in the case of a single AoA sensor failure. Not what the Boeing fix, if you can call it that, could do. By having two two AoA sensors in the loop, a disagreement can be noted and the MCAS function disabled. With two FCC involved, (not exactly sure why), additional failure modes may be detected and again, the function disabled. Not sure what pseudo-triplex means, but it does not offer what a full triplex architecture does.

Not sure if Boeing considered it, but one possible approach is to use non-AoA information from attitude and perhaps inertial sensors to detect a discontinuity in AoA sensor output as a validity check, and continue using the other AoA sensor if it is behaving normally. Not substituting the alternative attitude/inertial sensors for AoA, but only as a validity check. Only a thought, not trying to redesign the system.

[Chris2303]

So the protection given by MCAS in certain conditions of flight is a certification requirement?

How can that then be abrogated by disabling MCAS if there is an AOA disagreement?

[OldnGrounded]

So the protection given by MCAS in certain conditions of flight is a certification requirement?

Yes. That's what we have all been told.

How can that then be abrogated by disabling MCAS if there is an AOA disagreement?

Excellent question.

[gums]

Salute!

Outstanding question by Chris...

The problem is not using two sensors. The problem is not simply using one sensor, but alternating between the seats in the cockpit, and not telling either of them about the system and how it worked, and then disconnecting the column switches they had used for thousands of hours, and then...... and then.....

I will take a huge bet that if every Max pilot back in 2017 had to read a description of MCAS and potential problems if an AoA vane went south, and /or had a stick shaker going and various caution lights indicating airspeed problems or yada yada, and even best! a MCAS light! Imagine that?. How many crashes?

Good grief!

The pissant cert thing about stick forces is the most tiny problem in this mess. Besides obvious aero problems due to the new motors and their mounting, the crude attempt to meet FAA cert using a crude kludge and possible FAA negligence passing the cert, the failure to tell ME, the guy that has to get 150 folks to Topeka, Kansas is bordering on criminal.

The lawyers of the lost souls are gonna have a field day.

Gums sends....

[OldnGrounded]

I will take a huge bet that if every Max pilot back in 2017 had to read a description of MCAS and potential problems if an AoA vane went south, and /or had a stick shaker going and various caution lights indicating airspeed problems or yada yada, and even best! a MCAS light! Imagine that?. How many crashes?
Very few, if any. It would also have been nice to toss in a switch to disable MCAS without killing MET.

[HighWind]

With two FCC involved, (not exactly sure why), additional failure modes may be detected and again, the function disabled. .
This allow the system to detect if one of the two FCC's calculate a different value, due to a bit flip. This can then disable MCAS for the remainder of the flight, but it is not possible to detect the faulty FCC, and restart it. This is not a good design, since the two CPU's are loose coupled, there is limit on how much information they can check (bandwith), and there is a risk that they get out of sync. and fails safe (No MCAS, and maybe no autopilot?).
It would be better if each FCC had two CPU's (in the same enclosure) doing the same job (COM and MON), this make the FCC fail-silent i.e. the fault does not propagate to the other side.
It would also be good if in case of a faulted FCC, the remaining FCC has access to air-data sensors in the other side.

[MurphyWasRight]

Very few, if any. It would also have been nice to toss in a switch to disable MCAS without killing MET.
That switch existed on 737 until max, one of the two cutout switches disabled all automatic trim the other disabled all, including manual, electric trim.

This was discussed in the prior threads but no solid reason for change in MAX where either switch disables all electric trim.

Also brought up is that the training changed some time ago to allways use both switches on suspect trim runaway.

Had this changed not been made the ET crew might have been able to recover by enabling manual electric trim only.

[Fly Aiprt]

If the other involved airworthiness authorities got together and put together an acceptable to all package of requirements to recertify MAX and presented it to Boeing and FAA with a comply or die request!

Didn't EASA do that in a way some months ago, with its published key points ?
Boeing and the FAA would say they "appreciate the input, and are fully committed to work with the agencies"... and then continue whatever they are doing to this date.
What are they presently doing, by the way ?

[edmundronald]

Salute!

Outstanding question by Chris...

The problem is not using two sensors. The problem is not simply using one sensor, but alternating between the seats in the cockpit, and not telling either of them about the system and how it worked, and then disconnecting the column switches they had used for thousands of hours, and then...... and then.....

I will take a huge bet that if every Max pilot back in 2017 had to read a description of MCAS and potential problems if an AoA vane went south, and /or had a stick shaker going and various caution lights indicating airspeed problems or yada yada, and even best! a MCAS light! Imagine that?. How many crashes?

Good grief!

The pissant cert thing about stick forces is the most tiny problem in this mess. Besides obvious aero problems due to the new motors and their mounting, the crude attempt to meet FAA cert using a crude kludge and possible FAA negligence passing the cert, the failure to tell ME, the guy that has to get 150 folks to Topeka, Kansas is bordering on criminal.

The lawyers of the lost souls are gonna have a field day.

Gums sends....






Gums,

The lawyers for the deceased will get $2M per American passenger, peanuts for others, and mucho moolah for lawyers themselves.

Shareholder lawsuits, customer lawsuits, possible criminal negligence, and the MAX not flying for another year or two, now that’s a different story.

I think that for the Max to get certified again it will take either a miracle or a clear act of political policy, and from this point on the FAA will have to give clear written assurances that they will waive any right to contest ANY European or Chinese certification in the future. The reason being that something about the 737 needing MCAS is clearly not kosher, the native aerodynamics escaped scrutiny the first time round and can’t pass the regs that apply to civilian airliners, so certifying the Max with this envelope protection system will infringe on regulations, and that will be known to all in the business.

Edmund

[turbidus]

With two FCC involved, (not exactly sure why), additional failure modes may be detected and again, the function disabled. I understand how they did this, as it is easier to compare one FCC to another as the AOA vanes are wired one right and one left. What concerns me is this seems like reducing redundancy in some ways, as now you have lost the redundancy of 2 independent FCC's. There must be a whole Fton of cascading scenarios by tying the 2 together.
Doesnt it seem much more difficult to trace a fault through 2 FCC's? Comparing 3 versus 2 seems like far better redundancy and error trapping. Still the same with comparing 2, which one do you pick?

[Bend alot]

Consider this if you have time?
If the other involved airworthiness authorities got together and put together an acceptable to all package of requirements to recertify MAX and presented it to Boeing and FAA with a comply or die request!
What would be the likely reaction of Boeing and FAA to such a scenario?
Your thoughts and comments appreciated
Be lucky
David

The "thanks for the input" reply seems accurate.

Many/most regulators keep clear from giving solutions/advice on what to do or what will be accepted to be approved.

Mostly this is so they are immune to any faults that the solution/advice may contain when accidents happen. We have seen Boeing saying the FAA approved MCAS, but also that Boeing did not inform the FAA of changes made to MCAS during design.

Imagine if the FAA suggested the MAX needed MCAS to be certified?
Dennis would still be in the top job!

The regulators are (should) be there to confirm compliance of regulation are meet, not to tell companies how to meet compliance of regulation.

[GlobalNav]

I understand how they did this, as it is easier to compare one FCC to another as the AOA vanes are wired one right and one left. What concerns me is this seems like reducing redundancy in some ways, as now you have lost the redundancy of 2 independent FCC's. There must be a whole Fton of cascading scenarios by tying the 2 together.
Doesnt it seem much more difficult to trace a fault through 2 FCC's? Comparing 3 versus 2 seems like far better redundancy and error trapping. Still the same with comparing 2, which one do you pick?

If all the design does is compare two sources without anything independent for verification, you shouldn’t pick one. Functionality should require agreement between the two, otherwise shut it down. While triplex architecture compares three and disregards the outlier, there have been cases where the outlier was most correct. It’s called having a bad day. And when it happens there’s typically a common cause or condition that made the two wrong. Not a high probability, but it has happened with air data sensors. One reason that it’s useful to have independent and dissimilar system(s) to verify.

[MechEngr]

I understand how they did this, as it is easier to compare one FCC to another as the AOA vanes are wired one right and one left. What concerns me is this seems like reducing redundancy in some ways, as now you have lost the redundancy of 2 independent FCC's. There must be a whole Fton of cascading scenarios by tying the 2 together.
Doesnt it seem much more difficult to trace a fault through 2 FCC's? Comparing 3 versus 2 seems like far better redundancy and error trapping. Still the same with comparing 2, which one do you pick?

They are already tied together to disable the autopilot based on AoA disagree. Since the plane will be in fully manual control at that point it is up to the pilots, just like always.

[MechEngr]

That switch existed on 737 until max, one of the two cutout switches disabled all automatic trim the other disabled all, including manual, electric trim.

This was discussed in the prior threads but no solid reason for change in MAX where either switch disables all electric trim.

Also brought up is that the training changed some time ago to allways use both switches on suspect trim runaway.

Had this changed not been made the ET crew might have been able to recover by enabling manual electric trim only.

It might not have been required if the ET crew trimmed to neutral or even nose up before shutting off the trim. Recall that the electric trim was re-enabled at the point you are thinking of, but they did not retrim the airplane using electric trim; instead they tapped the button a couple of times without making a change to the stab trim and then attempted to re-enable the autopilot.

I suspect the change was made in order to prevent confused pilots shutting off the working trim system and allowing the erroneous one to keep working, much like pilots have shut down the remaining functioning engine in a panic.

[Longtimer]

A reviewing wiring issue that could cause short circuit on 737 MaxPUBLISHED SUN, JAN 5 20208:01 PM EST
https://fm.cnbc.com/applications/cnbc.com/resources/source_logo/2018/04/05/133240667-byline-reuters.png
KEY POINTS

The New York Times reported Boeing is reviewing whether two bundles of wiring are too close together, which could lead to a short circuit and potentially result in a crash if pilots did not respond appropriately.
The FAA said in a statement Sunday the agency and company “are analyzing certain findings from a recent review of the proposed modifications to the Boeing 737 MAX.”
Link to article: https://www.cnbc.com/2020/01/06/boeing-faa-reviewing-wiring-issue-that-could-cause-short-circuit-on-737-max.html
Boeing is currently working to design separating the wiring bundles if necessary and conducting extensive analysis to establish if the electrical fault could occur in a real-world scenario, a company official said.

[Australopithecus]

The article went on to say that the fix is basically a redesigned bracket which can be installed in an hour. The article also said that the new Boeing CEO's response was to fix all the aircraft as soon as the risk validation was complete. That response was contrasted by Muilenberg's preference for the lowest cost fix coupled with an aggressive PR stance.

GE apparently has troubling news about rotor shattering risk which the FAA is also reviewing which may renew the discussion about the rudder cable redundancy.

[Water pilot]

The FAA flagged the wiring issue as potentially “catastrophic.” It is possible other protections like shielding, insulation and circuit breakers could prevent the short circuit, a company official said.
This may not be a huge issue for the MAX, but I certainly hope that the engineering department had nothing to do with the statement that I highlighted because that is strictly an amateur's approach to electrical safety. Among many other things, despite popular belief a circuit breaker does not prevent fires from shorts, and this is especially true for partial shorts due to wiring insulation failure. Perhaps the MAX has arc fault detection but I doubt it (current technology is very prone to false activation and in an aircraft that can be fatal more quickly than in other applications.)

[Grebe]

WSJ article on Sim training and electrical

Just another case of save $200 re installing a few brackets and rerouting wiring- with net cost of probably $10,000- Boeing had similar problems on AF tanker( 767) at Everett since mil spec wiring isx tighter controlled than FAA - and first few tankers followed 767 commercial specs re wiring and had to be rewired to assure separation per Mil spec.

So they sent up electrical types from Renton P-8 to splain to everett types how to read the two syllable words in a mil spec and what they mean.

Took a few months to rewire-reroute and correct. Now it seems that renton had similar issues

But the stock prices and bone-us were up :\

And they saved a Million per plane for Southwest by not requiring more than a ipad review.

Only cost 10 Bilion and counting ...

Updated Jan. 5, 2020 7:05 pm EST








Federal aviation regulators are considering mandatory flight-simulator training before U.S. pilots can operate Boeing (https://quotes.wsj.com/BA) Co. BA -0.17% (https://quotes.wsj.com/BA?mod=chiclets) ’s 737 MAX jets again, according to government and industry officials familiar with the deliberations, a change that would repudiate one of the plane maker’s longstanding arguments.The Federal Aviation Administration months ago rejected the idea—which would entail extra costs and delays for airlines—as unnecessary.

But in recent weeks, these officials said, requiring such training before returning the grounded U.S. MAX fleet to the air has gained momentum among agency and industry safety experts.“The deliberations appear headed for a much different direction than before,” according to one of the officials, who described increased FAA emphasis on the topic.The FAA’s formal decision isn’t expected until February or later, and the situation remains fluid. An agency spokeswoman declined to comment on specifics, saying more analysis and testing is required.“The FAA does not have a timeline for this process,” she said. “And at this point our primary concern is ensuring a complete and thorough review of the aircraft.”A Boeing spokesman said: “We are thoroughly evaluating all aspects of a safe return to service including pilot training, procedures and checklists.” He added that Boeing will follow the recommendations of regulators world-wide and its priority is supplying any information they seek.Boeing has long maintained 737 MAX pilots don’t need supplemental simulator training beyond what pilots receive to fly other 737 models, a stance that many FAA officials now regard with increasing skepticism, according to the officials.

The FAA’s changed outlook on simulator training has arisen partly because Boeing and regulators are proposing rewriting some emergency checklists for pilots and creating some new ones, according to some of these officials.In addition, one of these officials said, the FAA expects certain cockpit alert lights to be updated so they can notify crews of potential problems with an automated stall-prevention feature called MCAS. Misfires of that system led to two fatal MAX nosedives in less than five months, taking 346 lives and resulting in global grounding of the planes in March.

Simulator training typically is used to ensure flight crews understand and can respond appropriately to numerous changes in emergency procedures or alerts.Since at least early fall, regulators in Europe, Canada and some Asian markets have signaled they are leaning toward mandating extra simulator training as part of their independent reviews of the MAX’s safety.The current tentative timeline projects FAA approval of an ungrounding order around March, after a group of international aviators—called the Joint Operational Evaluation Board—is slated to issue comprehensive training recommendations. After that, it would take weeks to inspect the idled planes, complete required maintenance tasks, brief foreign authorities and fly demonstration flights without passengers.










At this point, United Airlines Holdings (https://quotes.wsj.com/UAL) Inc. has said it is considering voluntarily implementing additional flight-simulator sessions for MAX pilots, though no final decision has been made. The airline has taken the MAX out of its schedules through early June. Airlines could point to such a requirement in their efforts to convince the flying public that the beleaguered airliner is safe, some of the officials said.


Complicating the FAA’s decision is an industrywide shortage of functioning 737 MAX simulators.In response, the FAA, Boeing and airlines are considering installing new software in existing 737 NG simulators so they can better mimic the characteristics of MAX jetliners, according to these officials.Meanwhile, agency chief Steve Dickson, a former airline captain and safety executive, plans to personally test software fixes and training changes as soon as the end of January or early February.

A year ago, when the FAA was analyzing earlier versions of MCAS fixes, Boeing argued strongly against upfront simulator requirements. The company said in a letter to the agency that differences between 737 NG and MAX models relating to the MCAS software “do not affect pilot knowledge, skills, abilities or flight safety.” At the time, FAA and Boeing officials tentatively agreed on training sessions that aviators could perform by themselves on tablets or laptop computers.The correspondence was released in October by the House Transportation Committee, which continues to investigate safety problems that have bedeviled the MAX, along with the FAA’s oversight of the plane’s initial design and subsequent proposed fixes.

Separately, a broader internal review of the MAX’s design by Boeing, extending well beyond software questions, has uncovered a potential safety problem stemming from the location of certain wire bundles inside the tail.The spacing of the bundles could cause an electrical short circuit resulting in a possible emergency that would require pilots to respond in as soon as four seconds to prevent the plane from going into a hazardous dive, said people familiar with the details. Information about the wire bundles was reported earlier by the New York Times. Various other MAX systems also have been re-examined since Boeing and the FAA in June revised long-held assumptions about pilot-response times.

An FAA spokesman said the agency will ensure that all safety related issues identified during the review process are addressed before the MAX is approved for return to passenger service.








A Boeing spokesman said the company is working closely with regulators on a robust and thorough certification process that includes assessing the safety of the wiring bundles. He added it was premature to say whether this will lead to a design change.

[Stribeck]

In the original NY Times article (nytimes.com/2020/01/05/business/boeing-737-max.html), there is another pretty remarkable statement that Reuters didn't include:

"Boeing also recently told the F.A.A. that it had discovered a manufacturing problem that left the plane’s engines vulnerable to a lightning strike.
While assembling the Max, workers at Boeing’s Renton, Wash., factory had ground down the outer shell of a panel that sits atop the engine housing in an effort to ensure a better fit into the plane. In doing so, they inadvertently removed the coating that insulates the panel from a lightning strike, taking away a crucial protection for the fuel tank and fuel lines. "

Can anyone explain exactly what this really means? Have they been using manual powertools to grind down components that doesn't fit during final assembly?

[Nil by mouth]

In the original NY Times article (nytimes.com/2020/01/05/business/boeing-737-max.html), there is another pretty remarkable statement that Reuters didn't include:

"Boeing also recently told the F.A.A. that it had discovered a manufacturing problem that left the plane’s engines vulnerable to a lightning strike.
While assembling the Max, workers at Boeing’s Renton, Wash., factory had ground down the outer shell of a panel that sits atop the engine housing in an effort to ensure a better fit into the plane. In doing so, they inadvertently removed the coating that insulates the panel from a lightning strike, taking away a crucial protection for the fuel tank and fuel lines. "

Can anyone explain exactly what this really means? Have they been using manual powertools to grind down components that doesn't fit during final assembly?

This thread and included links should explain what you are asking https://www.pprune.org/rumours-news/627922-787-lightning-strike-issues-v-faa.html

[Grebe]

From seattle times- Another article re Boeing breaking SPEEA pilots union may be posted elsewhere


By
Dominic Gates (https://www.seattletimes.com/author/dominic-gates/)
Seattle Times aerospace reporterDuring the exhaustive review of the 737 MAX systems demanded by safety regulators, Boeing has discovered a potential new wiring design problem that could add delay to the company’s target of returning the jet to service around March.

And a separate manufacturing issue affecting MAXs built over the past year will require hours of repair work on a large number of jets to ensure the engines are fully protected from a lightning strike before they can fly again.

The impact of the potential design problem inside some wiring bundles is still unknown.

According to an insider familiar with the details, Boeing engineers discovered “a theoretical possibility” of an electrical short circuit in wires connected to the jet’s moveable horizontal tail — known as the stabilizer — that could cause the tail to swivel uncommanded by the pilot, pushing the nose down.

Although this potential fault in the wiring bundles is unrelated to the flight control system that went wrong on the two crash flights in Indonesia and Ethiopia, Boeing said that as part of “a robust and thorough certification process to ensure a safe and compliant design,” it is analyzing the risk that it could produce a similar outcome to the crash scenarios.

“We identified this wire bundles issue as part of that rigorous process, and we are working with the FAA to perform the appropriate analysis,” said Boeing spokesman Gordon Johndroe. “It would be premature to speculate as to whether this analysis will lead to any design changes.”

The Boeing insider said it’s not yet clear if this is a real concern.

Our current understanding is that analysis may show that the theoretical fault cannot occur in the specific way required, and that other protections already in place – ranging from shielding to insulation to circuit breakers – would prevent it from being possible,” the insider said.

He added that company engineers are currently working to complete their analysis of the issue. Boeing is sharing its findings with the FAA and figuring out what if anything must be done to address it.

Both the wiring issue and the lightning vulnerability were first reported Sunday by The New York Times.Exploring all potential faults During the ongoing intensive review of the MAX systems, Boeing’s engineering team identified a theoretical scenario in which three wires routed close together might cause an electrical short that could result in “a high-speed continuous horizontal stabilizer runaway,” the insider said.

During the original certification of the MAX, Boeing’s system safety assessment classified such a “runaway stabilizer”—in which the horizontal tail swivels without pilot input to push down the nose of the jet—as a “major” hazard, meaning a flight upset that would likely cause only minor injuries to those on board.

Given the outcome of the two crashes, when both flight crews failed to cope with a runaway stabilizer, the event was reassessed last summer as “catastrophic” — two hazard levels higher, signifying a risk of losing the plane. A catastrophic hazard classification requires a design such that no single failure could trigger the event. That led to re-examining every possible system failure and the discovery of the potential electrical short.

This fault is not related to the flawed flight control software—the Maneuvering Characteristics Augmentation System (MCAS)—that contributed to the MAX crashes.

If further analysis confirms that the wiring is a real concern, the fix would require additional separation of a short segment of two wire bundles, the Boeing insider said.Adding more wire separation toward the tail of the airplane is difficult, because the structure narrows there and there is little extra room for maneuver.Even as Boeing engineers try to figure out if the failure could really happen, they are also working to design the separation.Manufacturing flaw left MAXs vulnerable to lightningThe separate MAX issue related to lightning protection is not a design but a manufacturing mistake.

On any jet aircraft, the two areas that draw the most lightning strikes are the nose of the airplane and the pods surrounding the engines that thrust out ahead of the wing. On the 737, the engine pods and the pylons that hold them to the wing, which are largely made of non-conducting carbon composite, have a metal foil just beneath the surface to safely disperse the current from such a strike.

Boeing said in a statement Monday that an incorrect manufacturing procedure used on some MAXs damaged the protective metal foil on two panels covering the engine pylons.

“On some airplanes built between February 2018 and June 2019, the protective foil inside the composite panels may have gaps,” Boeing said.

The pylons or struts holding the engines are covered on top by a couple of composite panels, resembling an elegant thumbnail resting on top of the engine pod. Boeing said operators of the affected jets will need to replace the two panels with new ones provided by the manufacturer.

Boeing is also asking all MAX operators to apply a sealant to establish a required electrical bond path. Boeing will provide the parts to ensure the bond path works as intended, the statement said.

A person with knowledge of the details said replacement of the panels with the damaged protective foil could be accomplished in about 5 hours, while the work to establish the electrical bond path will take approximately 20 hours.

All affected MAXs will have this done before they are allowed to fly again, the person said.

People close to the FAA process say that late February or early March remains the earliest that the agency could clear the MAX to fly again. But a federal government official cautioned that as the meticulous audit of the MAX systems continues, these two new issues may not be the last to be discovered.

“There’s no guarantee they won’t find other issues that need to be addressed,” the official said.

[phylosocopter]

"which could lead to a short circuit and potentially result in a crash if pilots did not respond appropriately."

Those other bloody pilots! Of course it wouldn't happen here ! [/sark}

[MechEngr]

From seattle times- Another article re Boeing breaking SPEEA pilots union may be posted elsewhere

Aside from the scare bolding, the electrical situation isn't as bad as it is made out to be. Electrical separation can be managed in a lot of ways besides physical separation.

I expect this one is: If there is a fire in the tail and the insulation is burned off, and then the remains of the wire's insulation comes off and then if the wires are moved so a power wire from something contacts the drive power wire for the trim motor, then couldn't that cause a problem? Or - suppose a worker just takes a knife and shaves off the wire insulation before installing the wires exactly where they go into a clamp, but arranged so they almost touch (so it passes functional inspection) and then after years of vibration they do touch, couldn't that be a problem?

I'm more perturbed by the allowance of post-acceptance part alteration that isn't called for in the engineering drawings. That's a practice that needs to be dealt with harshly.

[Senior Pilot]

Guys,

Despite best intentions this thread had become a Hamsterwheel with virtually nothing new being posted for some weeks. We were rehashing discussions and suppositions that were done to the nth degree in one or all of the numerous closed 737 Max threads.

The wiring issue has been merged (7th Jan 2020) as will anything else NEW and pertinent.

This will remain closed until some new and worthwhile progress in the saga appears and can be seen to be either a Rumour or News worthy of this forum. In the meantime there is a Hamsterwheel in JetBlast and also a discussion in SLF. Feel free to post suitable inputs there :ok:

https://www.nytimes.com/2020/01/05/business/boeing-737-max.html?action=click&module=Top%20Stories&pgtype=Homepage