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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 28th Jul 2019, 12:05
  #1581 (permalink)  
 
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Originally Posted by Less Hair View Post
To be fair to Boeing: There is no point in now suddenly requiring the grandfathered MAX to be built like a new airplane in every detail. Sort the sensors, MCAS, the trim, the processor, the training and/or pod aerodynamics and that's it. Opening a can of worms will lead to nothing. If future grandfathering should be abandoned by the authorities let manufactures know about well in advance for the next types and programs.
Well this is not my center of expertise, but if the risk of rudder cables being cut by shrapnel due to modified engine position and increased piercing capability due to increased moment of inertia and particle size this may not simply be grandfathered.
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Old 28th Jul 2019, 12:37
  #1582 (permalink)  
 
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But then it cannot be certified at all. By the nature of grandfathering it carries over old surpassed technologies and standards like many other aircraft do.
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Old 28th Jul 2019, 12:42
  #1583 (permalink)  
 
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Originally Posted by BDAttitude View Post
Well this is not my center of expertise, but if the risk of rudder cables being cut by shrapnel due to modified engine position and increased piercing capability due to increased moment of inertia and particle size this may not simply be grandfathered.
I think you mean momentum, rather than moment of inertia (though KE might be a more appropriate metric), and I don't really see how raising the engine (but with a thrust line the same distance from the aircraft's centreline) would make that much difference to the risk.

But re grandfathering, it's tempting to wonder at what stage in the Max development did Boeing wake up to the possibility that the heavier fan and HPT on the LEAP engine meant poorer containment characteristics, if indeed that's the case (npi).
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Old 28th Jul 2019, 12:57
  #1584 (permalink)  
 
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Originally Posted by DaveReidUK View Post
I think you mean momentum, rather than moment of inertia (though KE might be a more appropriate metric), and I don't really see how raising the engine (but with a thrust line the same distance from the aircraft's centreline) would make that much difference to the risk.

But re grandfathering, it's tempting to wonder at what stage in the Max development did Boeing wake up to the possibility that the heavier fan and HPT on the LEAP engine meant poorer containment characteristics, if indeed that's the case (npi).
To be more precise this is what I meant:

Larger fan diameter = larger anglular momentum, higher KE at impact.
New engine position (fan clear of the wings) = higher capture cross section of the fuselage
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Old 28th Jul 2019, 13:32
  #1585 (permalink)  
 
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Originally Posted by Bend alot View Post
I guess the most relevant precedent is that these questions have been asked of other systems by the same company on the same project.

It seems that the answer to those questions by said company were not very accurate, but very fatal.

You will need to supply the evidence to counter the FAA engineer/s concerns that the trim is adequate mitigation or effective mitigation - it seems not, and it was not addressed due to financial and deadline factors - not that it is not a safety problem. I do not have that information, they did.
This is getting to be depressingly similar to Challenger shuttle disaster where the historical "prove it is safe to fly" mandate to engineers was inverted to "prove it is not safe to fly" due to political and deadline factors.

Last edited by MurphyWasRight; 28th Jul 2019 at 13:35. Reason: wrong were thanks to spill chucker.
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Old 28th Jul 2019, 14:15
  #1586 (permalink)  
 
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Originally Posted by wonkazoo View Post
No boofhead, you've got it completely backwards. I'm going to go out on a limb here and speak for PilotMike and others: Our issue is that you are taking substantially incomplete information and coming to a definitive conclusion about a complex series of events that resulted in the deaths of many people. Not only are you coming to a conclusion prematurely you are placing the blame/responsibility squarely on those who are not here to defend themselves, which is precisely why waiting until the facts have been released to make such judgments is not only critical, it is the only decent thing to do. Finally, you are making these declarative judgments about actual now-deceased individuals and their performance not in a thread about pilot performance, training or whatever you want, but in a thread about the eventual (??) return of the 737 MAX and the impact of the FAA's review of their own certification process that led to the disaster in the first place.

Posting an off-topic post (or a dozen) is just rude. Flaying the dead before the facts have been fully revealed is pure cruelty.

My .02 as always, and thankfully I'm headed to a far away place where it is entirely possible I will be deprived of having to respond to posts like these. Lucky me!!

Cheers all-
dce

Im going to have to throw out the bs flag here. The vast majority of this thread consists of people here working with a substantial incomplete set of facts and drawing premature conclusions about a complex series of events that may or may not hold up once all the facts are known. Some here speculate, in an amazing amount of intricate detail I might add, about virtually every aspect of how Boeing and the FAA may have screwed this up and I dont see anyone calling for a halt to that discussion so it seems you only want to apply that rule only as it effects the crew. If you really think people need to STFU until all the evidence is in then they need to STFU about all of it and not just the pilot training issues. Personally I think the discussion is fine as long as it doesn't get personal. These accidents were ultimately about people and the choices they made whether they were an engineer, a test pilot, a Boeing manager, a FAA regulator, an airline executive, a aircraft technician, a training syllabus designer, and yes even a pilot. They all own a piece of this puzzle and they all are proper subjects of scrutiny.

As far as the "dead pilots" defense I strongly suspect that if by some weird twist of fate the entire Boeing design team was sitting in the back of one of the accident aircraft there wouldn't be lots of people saying we shouldnt' look at their decisions just becaused they perished. It doesn't matter what we think anyway because the crew issues will be looked at as it is in any accident investigaton. This isn't anything personal and no one is flogging the dead. They may have all been great people but they were a product of the industry that trained them and if that training was defective, which the evidence seems to indicate, then that training needs to be fixed before the MAX is allowed to fly.

You accuse Boffhead of going off topic, however the thread title has the words "reevaluation of 737 Safety Procedures" so excuse me if I point out that you can't really discuss procedures without discussing the end user, the pilots, who will be implementing those procedures and perhaps whether the existing procedures were adequate or were or were not implemented correctly and why or why not. There are a couple of parallel discussions in other PPRuNe threads that are talking about all the current problems with pilot training and experience worldwide and given what we know of the pilots response to the "complex series or events" I think their training or lack of same is very germane to the topic of "reevaluation of 737 Safety Procedures." I'm just as sick about the loss of life as anyone and I want to see alot of changes made through and through, not just fix the jet. Fix the crappy oversight by the FAA. Fix the "just the minimum" training philosophy. Fix the whole squeeze the costs out of every corner of the operation so we can make our quarterly numbers and get our bonuses mindset that made the MAX an accident waiting to happen. Just my .02 cents.
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Old 28th Jul 2019, 14:22
  #1587 (permalink)  
 
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Originally Posted by Notanatp View Post
Perhaps this was a symptom of being overweight? Not only did the captain ask to continue runway heading and say flight control problems, but the DFDR data looks a little odd (at least to me). There's a pretty steep pitch up initially (yanking it off at the end of the runway?), a shallow climb profile, and then a bit of sink when flaps retract.
Normal takeoff profile would consist of a relatively steep climb followed by a slight power reduction from takeoff thrust to climb thrust with decrease in climb rate to accelerrate and retract the flaps followed by an increase climb once climb speed was achieved. There is a tendency for the 737 to sink during flap retraction which needs to be countered with appropriate control inputs. If the Captain was not used to hand flying through the clean up phase and was distracted by the stick shaker it is entirely possibly that he was tardy with making the appropriate control inputs to keep from sinking. As far as the overweight question Im sure that is one of things that the investigation will look at but it does not appear that the aircraft was underperforming.


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Old 28th Jul 2019, 14:34
  #1588 (permalink)  
 
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Originally Posted by BluSdUp View Post
I have been busy lately on fulltime flying the 737-800 and a rather interesting spring and summer on the Home Front, so I have not been following this tread in detail.
The fallout of the MAX debacle is directly effecting my future so, I have great interest in what will soon happen or not happen.
The fact that NTSB soon is ready to speak on the matter is good news, as they are on the top of my list as an independent Organization and has great people with integrity working to keep an Old Skipper safe.
This I appreciate.

With regards to the schedule Boeing and FAA came out with for a return to service before XMass , I am afraid that just got pushed into late January , at best.
I sure hope I am wrong , but I seldom am in these matters. A born realist, or pessimist You may say.
Has worked for me for 31 years.

What worry me the most is the politics in this , and the fact that trust in FAA and Boeing has taken a big hit.
I hope that can be taken care of as a separate issue later and we can get on with flying this beast that I have come to love.

Greetings from Norway
( 32 Celsius , 20 in the Sea)
Cpt B
Cpt B

The fact that the Max incidents occurred in the third world seems to obscure for you and other first world pilots the fact that the MAX design has now been found to be flawed and it is alleged those flaws caused numerous deaths. The flaws need to be corrected, that is a reasonable expectation of the fee-paying passengers, not just "politics".

Edmund

Last edited by edmundronald; 28th Jul 2019 at 14:51.
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Old 28th Jul 2019, 14:59
  #1589 (permalink)  
 
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Originally Posted by Tomaski View Post
I'm just as sick about the loss of life as anyone and I want to see alot of changes made through and through, not just fix the jet. Fix the crappy oversight by the FAA. Fix the "just the minimum" training philosophy. Fix the whole squeeze the costs out of every corner of the operation so we can make our quarterly numbers and get our bonuses mindset that made the MAX an accident waiting to happen. Just my .02 cents.
The whole point of regulation is that as it applies equally to everyone it allows the setting of safety standards even when people naturally want to cut corners. The "minimum bar" can be raised, even if companies will still want to barely clear the bar.

Edmund
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Old 28th Jul 2019, 16:00
  #1590 (permalink)  
 
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Originally Posted by Less Hair View Post
But then it cannot be certified at all. By the nature of grandfathering it carries over old surpassed technologies and standards like many other aircraft do.
I may have misunderstood you here but grandfathering/readacross is fine until new technology, in this case the engines, provides a changed threat environment, then you have to redo the safety case including additional mitigation to overcome those new threats. It sounds as if the new engines have brought a new threat against the rudder cables - from just what has been reported - but the new engines would need full certification anyway so that should have been picked up on the Max "delta certification" work. Is the FAA now saying that this did not take place?
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Old 28th Jul 2019, 16:17
  #1591 (permalink)  
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Originally Posted by Hot 'n' High View Post
It sounds as if the new engines have brought a new threat against the rudder cables - from just what has been reported - but the new engines would need full certification anyway so that should have been picked up on the Max "delta certification" work. Is the FAA now saying that this did not take place?
According to the NYT investigative piece, linked above, FAA engineers were aware of the risk and suggested possible changes, but Boeing resisted and FAA managers ended up allowing B to self-certify the relevant design.

The F.A.A. engineers suggested a couple solutions, three of the people said. The company could add a second set of cables or install a computerized system for controlling the rudder.

Boeing did not want to make a change, according to internal F.A.A. documents reviewed by The Times. A redesign could have caused delays. Company engineers argued that it was unlikely that an engine would break apart and shrapnel would hit the rudder cable.

Most of the F.A.A. engineers working on the issue insisted the change was necessary for safety reasons, according to internal agency emails and documents. But their supervisors balked. In a July 2015 meeting, Jeff Duven, who replaced Mr. Bahrami as the head of the F.A.A.’s Seattle operation, sided with Boeing, said two current employees at the agency.

F.A.A. managers conceded that the Max “does not meet” agency guidelines “for protecting flight controls,” according to an agency document. But in another document, they added that they had to consider whether any requested changes would interfere with Boeing’s timeline. The managers wrote that it would be “impractical at this late point in the program,” for the company to resolve the issue. Mr. Duven at the F.A.A. also said the decision was based on the safety record of the plane.

Engineers at the agency were demoralized, the two agency employees said. One engineer submitted an anonymous complaint to an internal F.A.A. safety board, which was reviewed by The Times.

“During meetings regarding this issue the cost to Boeing to upgrade the design was discussed,” the engineer wrote. “The comment was made that there may be better places for Boeing to spend their safety dollars.”

An F.A.A. panel investigated the complaint. It found managers siding with Boeing had created “an environment of mistrust that hampers the ability of the agency to work effectively,” the panel said in a 2017 report, which was reviewed by The Times. The panel cautioned against allowing Boeing to handle this kind of approval, saying “the company has a vested interest in minimizing costs and schedule impact.”

By then, the panel’s findings were moot. Managers at the agency had already given Boeing the right to approve the cables, and they were installed on the Max.
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Old 28th Jul 2019, 16:29
  #1592 (permalink)  
 
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Re: Grandfathering regarding uncontained engines;

Grandfathering is based on the historical experience and in-situ demonstration of adequate safety. It is obviously measured against the initial design means of meeting the regs (in this case uncontained engine shrapnel) Any significant new experience across the total fleet s of all similar aircraft designs, beyond the B37 Max fleet, may be considered and as such "Special Condition" in the design required by the regulator.

I see no such unexpectedly bad experience among all recent worldwide designs since the latest update to the regulations or mean of compliance. Thus the Grandfathering should continue to be accepted..

Arguing about energy and particle size is simply minutiae in consideration of the current worldwide standards and experiences
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Old 28th Jul 2019, 17:39
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Grandfathering is based on the historical experience and in-situ demonstration of adequate safety. It is obviously measured against the initial design means of meeting the regs (in this case uncontained engine shrapnel) Any significant new experience across the total fleet s of all similar aircraft designs, beyond the B37 Max fleet, may be considered and as such "Special Condition" in the design required by the regulator.
Up to the MAX the engines were under the wings and therefore the rudder cables were effectively protected by the wing centre structure and therefore are compliant with the regulations at time of certification. In the MAX the engines are a new design so previous engine fail rates are irrelevant and they are now ahead of the wings so they plainly don't meet the regulations as specifically stated by Boeing themselves. There are obvious and proven mitigation strategies to eliminate the danger to the rudder cables, yet Boeing elected not to employ them for purely commercial reason with the acquiescence of the FAA.

Grandfathering by itself is not inherently bad, however I think there is an obvious requirement to fully assess the impact of changes to the baseline airframe and mitigate any new dangers. So far it appears that Boeing failed to do this with

1) The MCAS
2) Manual Trim wheel effectiveness at high air speeds
3) Rudder cable vulnerability to uncontained engine failures

This is not confidence inspiring........
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Old 28th Jul 2019, 18:08
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Thanks OldnGrounded, I thought that's where we were .... according to the NYT

Originally Posted by lomapaseo View Post
Re: ......... I see no such unexpectedly bad experience among all recent worldwide designs since the latest update to the regulations or mean of compliance. Thus the Grandfathering should continue to be accepted..........
lomapaseo, I'd actually agree with you - providing the threat level remained the same. Not being a Boeing engineer and knowing the designs in detail I've no idea. I'm just interested that the FAA seemed to have called this out so, was that because the new engines have somehow increased the risk or, is this a case of the "political dimensions" in the past that people have discussed. I have just seen Big Pistons Forever reply which seems to explain this nicely. My only interest is that I've been involved in adding weapons to updated aircraft and readacross/grandfathering was always an issue. What could be safely read across and what couldn't often caused interesting/heated discussions.
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Old 28th Jul 2019, 19:35
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Originally Posted by Big Pistons Forever View Post
Up to the MAX the engines were under the wings and therefore the rudder cables were effectively protected by the wing centre structure
There's not a great deal of wing in the plane of the fan on the NG:

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Old 28th Jul 2019, 19:56
  #1596 (permalink)  
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As disappointing as the saga of the MCAS is, the subject of the rudder control runs and the perception of a threat from a liberated fan blade should be considered rationally. A mob lynching doesn't assure the industry achieves what it needs, and would almost certainly lead to unintended consequences in due course.

MCAS's morphing of design wth what appears to be inadequate hazard analysis was disastrous. It is interesting to follow the discussion that arises on the altered relationship of the manufacturer to the regulator due to the ODA approval process. EASA has an equivalent process, DOA, for exactly the same reasons, and dependent on the same safeguards. ODA/DOA depend on a robust QA process, and it is that part that has let loose in the Max case. The regulator change to ODA/DOA is a consequence of rational realisation that the regulators are starved of manpower being unable to compete in most cases with the industry salaries. Adequate oversight requires retaining competency and staffing levels that is not possible in the current minimum funding of regulators. In principal, with good QA oversight, the ODA/DOA system in a substantial improvement over previous processes, but the entity's ethics on QA is central, and TBC's history of abuse of QA engineers places some doubt on that; they need a corporate clean out of ethics for real, not a repeat of the last effort arising from the KC-767 saga, where there was no acknowledgement of their actions on the B737 parts fabrication scandal.

The rudder... For 50+ years the plane in question has flown without an incident of a primary control being severed by an uncontained fan failure. The engine and nacelle design is supposed to protect from a liberated fan as part of the certification requirement. In the case of the 737, the SWA B737 in flight failure passing by Pensacola resulted in a fatality of a passenger, as had the MD82 disk failure years before. The risk to the aircraft that is not able to be mitigated arises from disk failure, not singular fan blades. In general, as seen on UAL232, QFA032, and the AA B767's, a disk failure is potentially a catastrophic event, the defence is not having them, and that comes from having good metallurgical design and processing, good structural design, and as much redundancy as possible in critical systems architecture. QFA032 showed that you can still have a bad day, and not just because the manufacturer is Boeing and the product is called a Max.

I would have more interest in sorting out the manual trim issues by at a minimum providing a training program to remove the cobwebs of time past than to worry over a fan blade issue, where the risk of a disk failure is vastly more problematic and almost impossible to mitigate, it is to be avoided.
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Old 28th Jul 2019, 20:32
  #1597 (permalink)  
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Originally Posted by fdr View Post
I would have more interest in sorting out the manual trim issues by at a minimum providing a training program to remove the cobwebs of time past than to worry over a fan blade issue, where the risk of a disk failure is vastly more problematic and almost impossible to mitigate, it is to be avoided.
I think the most concerning part of the FAA internal dispute over the threat to the rudder cables from uncontained failure is that the engineers involved believed that management was improperly weighing cost and efficiency (as seen by B) versus safety. Remember that the Times investigators reviewed an FAA document that conceded that the design doesn't meet the guidelines for protecting flight controls and that the FAA's own panel investigating the engineer's formal complaint found that the managers who took B's side in the disagreement created “an environment of mistrust that hampers the ability of the agency to work effectively.”

The environment depicted by the Times story (along with a fair amount of similar material we've been seeing) seems fundamentally damaging and dangerous in and of itself, aside from questions about quantifying the risk to the rudder cables.

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Old 28th Jul 2019, 20:32
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It is perhaps just that the combination of crony regulation and Boeing arrogance generated a firestorm of regulatory rejection.
In this instance, the public weal was clearly disregarded by the FAA.
What I do not see is the path forward to general regulatory re-acceptance of the MAX. No regulator will bless this kludge, knowing that the next disaster puts them personally in the line of fire.
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Old 28th Jul 2019, 20:36
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Originally Posted by Imagegear View Post
How well is the code in the MCAS understood by non-software engineering guru's outside of Boeing?.
It will be completely non understood to all non software engineering people, everywhere.

I'd leave the engineering to the engineers . . .
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Old 28th Jul 2019, 23:57
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Pandora’s Box

a process that once begun generates many complicated problems.
The MAX issue certainly fits the definition, firstly it was the MCAS then the trim system now we’ve moved onto the rudder cables. Where to next ?
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