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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 22nd Aug 2019, 07:22
  #1981 (permalink)  
 
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Short term storage advice is to store them with full (or close to full between engine runs) tanks with biocide additive and sump drains checked for water periodically. The more fuel in the tank the less ullage volume, the less air (with moisture) drawn in with each daily temperature cycle, and the less condensation of water in the tank. It's the same approach most people take with a fishing boat stored over the winter.
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Old 22nd Aug 2019, 09:43
  #1982 (permalink)  
 
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Originally Posted by Loose rivets View Post
Assuming drip checks, are there any advanced fuel analyses that have to be done on months-old fuel?
The molecules in that fuel are already billions of years old.
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Old 22nd Aug 2019, 10:00
  #1983 (permalink)  
 
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Originally Posted by flynerd View Post
The molecules in that fuel are already billions of years old.
Er no.

The formation of the hydrocarbon deposits from which human activity extracts and refines petroleum products started millions of years ago (pedantry ought to be accurate to 10^3 no?)

When extracted and subsequently refined the product that goes into the aircraft is no longer that stable admixture of petroleum types nor is it being held in the same conditions under which it was stable.

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Old 22nd Aug 2019, 10:54
  #1984 (permalink)  
 
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2-3 years! guess some are due now and very soon for others
  • C check – every 4-6,000 FH / 2-3 years. Now P8, P10 or P12 checks.
24 Max delivered 2017 & 330 in 2018.

737 Heavy Maintenance

Last edited by Bend alot; 22nd Aug 2019 at 10:56. Reason: Get the year right.
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Old 22nd Aug 2019, 12:58
  #1985 (permalink)  
 
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Aircraft have been going in and out of storage for ages. Nothing new, except for the scale of the operation.
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Old 22nd Aug 2019, 13:38
  #1986 (permalink)  
 
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Originally Posted by golfyankeesierra View Post
Aircraft have been going in and out of storage for ages. Nothing new, except for the scale of the operation.
Storage is generally a plan - sudden grounding then a "where to put them" does not serve well for heavier maintenance requirements down the track.

Not forgetting different countries, have different rules to allow a "dispensation" for a maintenance requirement/s even for a ferry flight on over due maintenance.
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Old 22nd Aug 2019, 15:16
  #1987 (permalink)  
 
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Originally Posted by flynerd View Post
The molecules in that fuel are already billions of years old.
The compounds in fuel can degrade rather quickly unless stored in ideal circumstances, due to oxidation or the action of the various organisms that can feed upon them. Anybody who has tried to start a lawnmower after it has been stored with fuel in it over winter has experienced that. There is a whole industry that makes chemical additives to combat this problem, and from my experience the success rate is not exactly 100%. The problem for Boeing is that a success rate of 99% would not be good enough, only a few planes having issues with fuel after storage would be a bad thing. After all, they only crashed two of them after thousands of flight hours; the rules are different for aircraft than lawnmowers and yachts.
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Old 22nd Aug 2019, 19:27
  #1988 (permalink)  
 
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Originally Posted by Bend alot View Post
Storage is generally a plan - sudden grounding then a "where to put them" does not serve well for heavier maintenance requirements down the track.

Not forgetting different countries, have different rules to allow a "dispensation" for a maintenance requirement/s even for a ferry flight on over due maintenance.
I think we all agree it is going to be a logistics nightmare, I am very interested how it is going to work out, but discussing fuel quality of stored aircraft is a mega thread drift.
It has zero relevance to the Max’s recertification and return to service.
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Old 22nd Aug 2019, 20:24
  #1989 (permalink)  
 
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I think it has rather a lot of relevance to the "return to service" part, even if it is just a matter of public perception. From the airline's point of view, life is being sucked out of the planes as they sit outside in various conditions getting cold started once in awhile. I'm not an engine guy nor a Jet guy, but from experience engines that sit idle have a much shorter service life, at what point this kicks in for Jets I won't even pretend to know. More than once I have met people who were thrilled to buy an older, low-hour yacht only to have to do an engine replacement in their first season while the purchaser of the one with the high hours, worn interior but a well-cared-for engine just keep on chugging along into antique status.
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Old 22nd Aug 2019, 20:39
  #1990 (permalink)  
 
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Originally Posted by flynerd View Post
The molecules in that fuel are already billions of years old.
The atoms in the fuel are billions of years old. The molecules are only a few weeks old, having been recently synthesized in a hydrocracker at the refinery.
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Old 22nd Aug 2019, 20:45
  #1991 (permalink)  
 
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Technically, fuel molecules have not been synthesized at the refinery, but separated from different kinds of molecules.
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Old 22nd Aug 2019, 21:48
  #1992 (permalink)  
 
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Satcom Guru

Peter Lemme has posted a deep analysis of the differences between NG and MAX stab trim systems as well as the proposed changes:

​​​​​​Connecting the Dots: From Command to Action
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Old 23rd Aug 2019, 00:09
  #1993 (permalink)  
 
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Originally Posted by Zeffy View Post

Peter Lemme has posted a deep analysis of the differences between NG and MAX stab trim systems as well as the proposed changes:

​​​​​​Connecting the Dots: From Command to Action
Wow that is some serious analysis! Thanks for posting.

Something which won’t help those arguing ‘pilot error’ is the fact that on the MAX, the previous NG logic where an aft column cutout switch inhibits any ongoing nose down trim is absent. That means that simply following any runaway trim procedure will lose the precious seconds needed to discover that although you are pulling back on the column, the automatic nose down trim is still being activated. If pilots were not informed that MCAS existed I can’t see how they would automatically know that the cut out switch logic had changed.

Not only are seconds lost discovering this but then this is followed by the inevitable “Hold on a minute, that was unexpected. What the hell is going on here?” moment, which not only loses more time but also disturbs the cognitive flow needed to first analyse the problem and then apply a solution.

Too many 737 pilots now know the situation on the MAX for it to be of any statistical use, but early on in this process it would have been interesting to have thrown a number of line pilots into the false MCAS operation/low altitude/climb power situation in the sim, to see exactly how many would analyse the problem and fly out of it and how many would end up flying it into the ground.
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Old 23rd Aug 2019, 04:09
  #1994 (permalink)  
 
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Seattle Times

https://www.seattletimes.com/busines...urn-to-flight/
Boeing and FAA give more signs of preparations for a 737 MAX return to flight

By Dominic Gates
Seattle Times aerospace reporter

Thursday brought more strong hints that Boeing and the Federal Aviation Administration are moving steadily toward ungrounding the 737 MAX as soon as October.

The FAA said Thursday it’s inviting “a cross-section of line pilots from carriers that operate the aircraft around the world” to participate in simulator testing “as part of the overall testing and validating of new procedures on the Boeing 737 MAX.”

And according to two sources with knowledge of the matter, the FAA’s Flight Standardization Board that determines U.S. pilot-training requirements aims to issue in early September new recommendations for exactly what MAX pilot training is needed before U.S. airlines can fly passengers on the airplane again.

Meanwhile, Boeing gave suppliers a new 737 production schedule reflecting “timing assumptions for the 737 MAX return to service plan.”

The updated schedule is aggressive. Assuming FAA clearance in October, Boeing plans to begin the ramp-up immediately, moving from the current 42 planes per month to the pre-crash production level of 52 jets per month by February and reach a new high of 57 jets per month by next summer.

The simulator sessions the FAA plans for line pilots will test new procedures related to Boeing’s the updated Maneuvering Characteristics Augmentation System (MCAS) flight control software, the original version of which went haywire in the two fatal MAX crashes in Indonesia and Ethiopia and repeatedly pushed the nose of each jet down.

Because of a potential new computer glitch discovered in June, pilots may also run through separate procedures handling uncommanded nose-down movements unrelated to MCAS.

Boeing and FAA pilots have been testing the updated MCAS software for months. What’s significant is that the FAA is now inviting regular 737 MAX line pilots to do the same.

The assumed response time of pilots to an emergency, whether due to MCAS or not, has been under scrutiny since the crash of the Ethiopian Airlines MAX in March, when the pilots tried and failed to follow a standard recovery checklist.

FAA guidelines say that if an emergency arises on a plane flying by autopilot, the assumption is that a pilot will begin to respond within three seconds. If the plane is being flown manually, the assumption is one second. When FAA test pilots deliberately delayed their responses in a simulation in June, one of the pilots crashed the plane.

The safety agency said the line pilots now being invited to the new simulator tests will be pilots with “previous experience at the controls of the Boeing 737 MAX.”

“A firm schedule for these tests has not been set, although they must be completed before the aircraft is approved for return to service,” the FAA said in a statement.

Those simulator sessions are designed to validate the safety of the MAX with a regular pilot at the controls.

Dennis Tajer, an American Airlines captain and spokesman for the Allied Pilots Association union, said that “anything that gets the average line pilot in to test that system — not the top test pilot at Boeing but an average 737 pilot — that’s realistic analysis and we’re encouraged to hear that.”

At the same time, the FAA’s Flight Standardization Board (FSB) is preparing to issue new guidelines early next month for the training that all U.S. airline pilots must receive before flying the MAX again.

In April, the board issued a draft report after reviewing the initial MCAS fix Boeing had designed, which it “found to be operationally suitable.”

That report said full-flight simulator training, which is time-consuming and expensive for the airlines, is unnecessary ahead of clearing the plane to fly again. Instead, the board recommended only a short computer-based course and classroom instruction about the new software update.

That report was shelved as Boeing’s software update kept getting pushed further out. If the new training outline coming in September sticks to the previous recommendation that simulator training is not needed, that will boost the MAX’s return-to-service schedule, which is crucial to the airlines and to Boeing.

The U.S. airline-pilot unions have said they could support such a recommendation provided that training specifically on how to handle uncommanded movement of the horizontal tail is included in the recurrent simulator training that every U.S. airline pilot must go through, typically every nine months or so.

The report by FAA’s Flight Standardization Board coming in September will have a comment period no longer than 30 days to gather input from the airlines and pilots before it’s finalized and made mandatory. This timeline meshes with Boeing’s publicly stated hope to get the MAX flying again commercially “in the early fourth quarter.”

Even if the FAA doesn’t mandate simulator training before the MAX returns to flight, there’s no guarantee for Boeing that some overseas regulators won’t come up with different requirements. But most foreign safety agencies seem likely to follow the FAA’s lead.

Separately, Boeing said Thursday that, contingent upon FAA clearance, it has come up with a new 737 MAX production schedule that can meet the target set by Boeing Chief Executive Dennis Muilenburg in July: ramping up to a new production level before the end of 2020.

Boeing said the production plan, which has been communicated to suppliers, “assumes a gradual increase in the 737 production rate from the current 42 per month to 57 per month in 2020.”

On Thursday, Reuters outlined the planned incremental steps, citing supplier sources. The Reuters report said Boeing’s plan is to increase production from 42 to 47 aircraft per month in October, as soon as regulatory approval to fly is granted. It would then increase production to the pre-crash rate of 52 aircraft per month in February, and to 57 jets per month in June 2020.

Still, all of this timing depends upon the regulators, here and overseas.

Boeing cautioned in its statement that “while the assumption reflects Boeing’s best estimate at this time, the actual timing of return to service will be determined by the FAA and other global aviation regulatory authorities.”

Dominic Gates: 206-464-2963 or [email protected]; on Twitter: @dominicgates.
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Old 23rd Aug 2019, 05:10
  #1995 (permalink)  
 
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Nothing of EASA issues being addressed, or what the fix is.

But we tested it, now we will get line pilots to test it.

It all happens in the background so you do not need to know about it.

All good - stamp please.
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Old 23rd Aug 2019, 05:44
  #1996 (permalink)  
 
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That means that simply following any runaway trim procedure will lose the precious seconds needed to discover that although you are pulling back on the column, the automatic nose down trim is still being activated.
Your statement completely ignores the fact that if a pilot is pulling back (is there any other way to pull) on the control column and they find that it is getting heavier, then they would naturally and instinctively use rear trim (nose up) using the electric trim switch on the column, which would then inhibit MCAS operation.
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Old 23rd Aug 2019, 10:00
  #1997 (permalink)  
 
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Originally Posted by Icarus2001 View Post
Your statement completely ignores the fact that if a pilot is pulling back (is there any other way to pull) on the control column and they find that it is getting heavier, then they would naturally and instinctively use rear trim (nose up) using the electric trim switch on the column, which would then inhibit MCAS operation.
Question, from an interface-design/engineering point of view, what is then the rationale for EFS? To make the control column get heavier because (assuming working AOA sensors) we are approaching stall, so the pilot then naturally and instinctively trims nose up? Really?

Subsidiary question: what is the pilot's natural and instinctive reaction to being pushed back into his/her seat by +ve g when trimming up?
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Old 23rd Aug 2019, 10:17
  #1998 (permalink)  
 
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Originally Posted by Zeffy View Post
Peter Lemme has posted a deep analysis of the differences between NG and MAX stab trim systems as well as the proposed changes:

​​​​​​Connecting the Dots: From Command to Action
Interesting analysis. He says there:

As has been described to me, Boeing will move MCAS (speed trim commands too?) to a dual architecture. In a dual architecture, each FCC has a full set of dedicated sensors to draw from; therefore no single point failure on inputs. If both FCC commands must agree for trim commands to be valid, then malfunction of one FCC can be suppressed.
Since when has aviation done anything other than dual architecture?
Who in the Boeing design team thought single architecture was a good idea?
Who in the Boeing management team thought single architecture was a good idea?
Who in the Boeing flight testing team thought single architecture was a good idea?

How did a single-channel MCAS ever get fitted to a 21st century aircraft?

Silver
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Old 23rd Aug 2019, 10:28
  #1999 (permalink)  
 
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Originally Posted by Icarus2001 View Post
Your statement completely ignores the fact that if a pilot is pulling back (is there any other way to pull) on the control column and they find that it is getting heavier, then they would naturally and instinctively use rear trim (nose up) using the electric trim switch on the column, which would then inhibit MCAS operation.
A basic tenet of aviation, is you are not supposed to (allowed to) use the trimmer as a primary flight control. It is only there to remove stick loads, after a manoeuvre has been completed. You can get yourself in a right Branston if you fly the trimmer, which is why most people would delay the use of trim.

The 737 speed-trim has undermined that basic tenet, because it is always placing the aircraft out of trim, but still there should be a considered delay before using the trimmer.

Silver
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Old 23rd Aug 2019, 10:36
  #2000 (permalink)  
 
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... the average line pilot in to test that system — not the top test pilot at Boeing but an average 737 pilot...
They haven't been reading their PPRuNe

​​​​​​It was pointed out some time ago that if they aimed at the "average" pilot, that may leave 50% of pilots unable to cope.

They need the worst case pilots, the least able ones. Which leaves an interesting question- how do you get hold of them?

"Hey you've been specially selected for this brand new testing event at the FAA!"
"Is that because of my outstanding skills and experience? "
​​​​​​" errr... "
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