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

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

Old 6th Jan 2020, 02:47
  #281 (permalink)  
 
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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.

Last edited by Australopithecus; 6th Jan 2020 at 04:28.
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Old 6th Jan 2020, 04:25
  #282 (permalink)  
 
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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.)
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Old 6th Jan 2020, 05:21
  #283 (permalink)  
 
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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 Co. BA -0.17% ’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 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.
















Last edited by Grebe; 6th Jan 2020 at 05:40. Reason: broke into paragraphs for easier reading
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Old 6th Jan 2020, 10:51
  #284 (permalink)  
 
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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?
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Old 6th Jan 2020, 11:05
  #285 (permalink)  
 
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Originally Posted by Stribeck View Post
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 787 Lightning strike issues v FAA
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Old 7th Jan 2020, 02:30
  #286 (permalink)  
 
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Exclamation More wiring details vs Stabilizer and lightning

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

By
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 lightning

The 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.

Last edited by Grebe; 7th Jan 2020 at 02:38. Reason: clarify
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Old 7th Jan 2020, 03:57
  #287 (permalink)  
 
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"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}
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Old 7th Jan 2020, 06:15
  #288 (permalink)  
 
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Originally Posted by Grebe View Post
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.
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Old 7th Jan 2020, 07:21
  #289 (permalink)  
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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

https://www.nytimes.com/2020/01/05/b...gtype=Homepage
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