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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 14th Aug 2019, 02:06
  #1821 (permalink)  
 
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Posturing? -- Seattle Times

https://www.seattletimes.com/busines...es-other-jets/

Southwest, a stalwart Boeing 737 MAX customer, eyes other jets
Aug. 13, 2019 at 2:12 pm Updated Aug. 13, 2019 at 3:46 pm

By Dominic Gates
Seattle Times aerospace reporter

Southwest Airlines, the largest customer of the 737 MAX and long an all-Boeing airline, insists it has “no current plans” to fly any jets other than the 737. But it’s at least eyeing the possibility.

The airline’s management has proposed new language in the contract with its flight-attendants union that would grant it the flexibility “to fly more narrowbody aircraft types.”

Southwest management told the union, TWU Local 556, in a proposal this month that the ability to operate aircraft other than the 737 “would give us the flexibility … to better compete and grow.”

“We are flying to more destinations that vary in distance, size and seasonality,” the company’s proposal states. “This change would allow us to fly aircraft types that are better suited for some of the markets we serve.”

The grounding of Boeing’s 737 MAX has hit Southwest hard. The airline has 280 of the jets on order, of which 34 were delivered and in passenger service before the grounding.

Jon Weaks, president of the Southwest Airlines Pilots Association, said in an interview that the carrier’s chief executive, Gary Kelly, “has bet the company on the MAX.”

The airline has parked its current fleet of MAXs at an airfield in Victorville, California. And it has another 41 contracted MAX deliveries for the remainder of this year that Boeing will hold until it gets clearance for the jet to fly passengers again. At this point, those aircraft won’t be in service until next year.

The 75 jets parked or awaiting delivery represent 10 percent of Southwest’s active fleet of 750 aircraft, putting the low-cost-carrier at a competitive disadvantage against other airlines with fewer MAXs or, as is the case with rival Delta, none.

In April, as anger against Boeing built among U.S. airline pilots after the second MAX crash in Ethiopia, Weaks wrote a memo to SWAPA pilots noting that some were questioning the wisdom of an all-737 fleet.

Weaks wrote that his pilots as well as Wall Street analysts have discussed “the advantages and disadvantages of an airline having a single fleet and having aircraft from only one manufacturer.”

He also referred to Boeing’s size and enormous influence in the aerospace world “and the antitrust issues that accompany this long-overlooked issue.”

This year, there was speculation that Southwest might buy the new Airbus A220, an all-new jet formerly known as the CSeries that the European jet maker acquired from Bombardier of Canada. Delta is now using that very fuel-efficient plane, which is small but offers the cabin comfort of bigger jets, to connect city pairs with high business demand, including Seattle-San Jose.

At a conference in March, five days before the second MAX crash, CEO Kelly admitted that Southwest has looked at the A220 but said that was just normal due diligence to assess all options.

“As new technology comes onto the market, I think we’re compelled to look at that,” Kelly said. But he added that it would take “a really compelling business case for us to deviate from” the current all-737 fleet.

That was before the MAX was grounded. Asked again on an earnings call last month about whether he might look at buying different jets, Kelly said it’s a longer-term strategic decision that wouldn’t solve the immediate problem.

“I think it’s something that needs to be fully explored and debated, and that’s not something we’re going to do in 90 days,” he said. “As a practical matter, if we want to diversify the fleet, it would take us years.”

Asked if Airbus is “circling you more aggressively” during the MAX crisis, Kelly said, “Yes, that’s always the case.” But he again insisted that “right now, we don’t see that we need a change in strategy.”

Responding via email to an inquiry Tuesday, Southwest spokeswoman Beth Harbin said, “Southwest has no current plans to pursue or introduce a new fleet type.”

The negative impact of the MAX grounding has led Wall Street analysts to wonder if Southwest may even consider acquiring another airline and bringing in different jets that way. Kelly pointed out in July that Securities and Exchange Commission (SEC) rules mean “we can’t comment on anything like that in substance” beyond saying that such a step would be “a huge strategic question.”

So does the proposed new language in the flight-attendant union contract indicate a shift in thinking?

TWU Local 556 President Lyn Montgomery said that when union negotiators asked management if they intended to bring in a new aircraft type in the future, “they said they had no plans.”

Pilot union president Weaks said that no new aircraft could be introduced without negotiating with SWAPA the pay rates for flying it. “There’s been no communication to us at all” on the issue, he said.

Harbin said the proposed clause in the flight-attendant contract is simply intended to provide the option to diversify in future.

“It is somewhat common at the negotiating table to discuss items that give you flexibility upfront for things you don’t currently have or even have a plan for,” she said.

Still, in the corporate world, “no current plan” is a response that can change with a simple announcement. That the 737’s largest customer, after what Boeing notes is a “48-year partnership,” is even contemplating the idea — one that its CEO says “needs to be fully explored” — may be unnerving enough for Boeing.

Dominic Gates: 206-464-2963 or [email protected]; on Twitter: @dominicgates.
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Old 14th Aug 2019, 02:49
  #1822 (permalink)  
 
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Originally Posted by Paul Lupp View Post
" Defence News reported earlier this year (2018) that the US Army had stopped taking deliveries of the AH-64E Apache attach helicopters from Boeing in February. The US Army explained that 'the service is not confident in the durability of what it deems a "critical safety item" - a strap pack nut that holds very large bolts, that subsequently hold the rotor blades on the helicopter'
(snip)
Suggest that you look into the Apache (D) crash a few years ago near Houston, Texas, if you want to understand that issue with the Apache. Short version: one blade left, and it all ended in tears. You will not find anything about that here on the fixed wing noiseathon regarding the 737 Max, but you may, if you use the search function, find some items of interest in the Rotorheads or Military Aviation forums. The strap pack nut figured prominently in that accident. With the increase in max gross weight for the E, a variety of issues regarding component life arose Long Before MCAS was a term anybody knew.
Plus: that's Boeing Mesa, Rotary Wing.
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Old 14th Aug 2019, 03:07
  #1823 (permalink)  
 
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Ryanair are supposedly considering Airbus as well though long term committed Boeing customers may find it worthwhile to stick with Boeing and drive very hard on price whilst being number one in the queue for the new narrow body MAX replacement when it arrives. A clean sheet design would probably outperform the A320NEO so Airbus might get into an arms race with Boeing to build an even better A320 replacement, something both companies have tried to avoid.

Of course it could just be a bargaining position. Airbus didn't bother talking to British Airways for years as they felt they were wasting their time and were simply being used to help BA get a better price from Boeing. When BA first bought Airbus aircraft they had to go to Toulouse and convince the sales department that they were serious.
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Old 14th Aug 2019, 03:33
  #1824 (permalink)  
 
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A clean sheet design would probably outperform the A320NEO so Airbus might get...
Just how long do you think that would take to bring to the market?
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Old 14th Aug 2019, 06:42
  #1825 (permalink)  
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Originally Posted by Icarus2001 View Post
Just how long do you think that would take to bring to the market?
Probably not that much later than Airbus' available delivery slots?
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Old 14th Aug 2019, 07:08
  #1826 (permalink)  

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Originally Posted by nyt View Post
Probably not that much later than Airbus' available delivery slots?


I think the problem is the efficiency sought.
- 737NG already has CFD wing
- the new engines are same for both
- fuselage won't add up to much, the tail has already been tweaked thrice.

So you can do weight.
- But a composite hull (787) for a shorthaul a/c needs to take a lot of beating on the ramp. Also the aftermarket needs aftermarket repairs, availability of both affects the sales price. Sales price needs to cover the development cost and here the two go against each other.
- go fly-by-light, all electric FCS. Sadly the recent even shows Boeing and their ecosystem do not have the skills to achieve that, present day.
- a plethora of unspecified small improvements. Which are also available to Airbus on their current airframe, hmm.

So all new airframe then, once materials and technologies that are not available now become suitable for mass production and field deployment. At the same time when 320NEO is becoming obsolete, not sooner.

my 2pc.

Last edited by FlightDetent; 14th Aug 2019 at 09:20.
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Old 14th Aug 2019, 08:17
  #1827 (permalink)  
 
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Just how long do you think that would take to bring to the market?
That is exactly the type of thinking that got them into this mess. A new type was always to far away for the senior management so they just kept on kicking the can down the road hoping it will become someone else's problem. Unfortunately for the current team the music stopped whilst they were holding the parcel.
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Old 14th Aug 2019, 09:25
  #1828 (permalink)  
 
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'TUI says that the grounding of the Boeing 737 Max will cost the holiday group €300m. It said: "Resumption of the 737MAX remains subject to the clearance decision of the civil aviation authorities and we have secured replacement aircraft leases out to the end of our Summer 2019 programme." The company made the disclosure in its third quarter results where it reported a 3.7% rise in sales to €4.7bn. Pre-tax profits, however dropped by 58.2% to €58.9m.'
https://www.theguardian.com/business...-to-300m-euros
This is good news because it seems to me that the only thing the aviation industry and its customers (right down to SLF) really cares about is money and therefore if the Max catastrophe costs everyone concerned a lot of money perhaps safety will claw its way back up the agenda towards its rightful position. Perhaps. Maybe. I am SLF on a flight this morning at a ludicrously low fare (less than a meal in an average restaurant), using an elderly turboprop on a shuttle island-hop, and I do wonder....
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Old 14th Aug 2019, 09:51
  #1829 (permalink)  
 
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Maninthebar, #1832 not known; the background is in the EASA reference below.

“Simulation has demonstrated that the thumb switch trim does not have enough authority to completely trim the aircraft longitudinally in certain corners of the flight envelope,”

“The trim wheel can be used to trim the airplane throughout the entire flight envelope. In addition, the autopilot has the authority to trim the airplane in these conditions.
The reference regulation and policy do not specify the method of trim, nor do they state that when multiple pilot trim control paths exist that they must each independently be able to trim the airplane throughout the flight envelope.”
“The main issue being that longitudinal trim cannot be achieved throughout the flight envelope using thumb switch trim only.

Boeing set the thumb switch limits in order to increase the level of safety for out-of-trim dive characteristics (CS 25.255(a)(1)). The resulting thumb switch limits require an alternative trim method to meet CS 25.161 trim requirements in certain corners of the operational envelope.

The need to use the trim wheel is considered unusual, as it is only required for manual flight in those corners of the envelope.”

The inference is that the stick trim switches are electrically inhibited at a particular tail position, preventing either ANU or AND movement (otherwise it would invalidate the purpose of inhibition for safety reasons - trim runaway).

Points to note: the ‘discrepancy’ was noted in simulation. ‘Authority’ or inhibited?
Apparently (significant speculation) the use of trim wheel, in simulation (as the alternative to elect trim) was restricted to the certification overspeed requirements, and not the full range of physical trim movement, or ability to manually trim over this trim range. Thus did not identify any inability to move the trim manually.

Apparently the autopilot / auto trim has the ability to trim over full range. This is ambiguous; either as required for autopilot control - stay in trim, but not manual trim cert requirements. Also, this could invalidate the safety inhibition as above - trim is still electrically enabled, and ‘if so’, and ‘if’ MCAS was routed via the ‘auto’ FCC, then it could electrically signal the tail to move in conditions which the stick trim could not.

Reference to ‘aisle stand trim switches’ is confusing, perhaps trim wheel.

https://www.easa.europa.eu/sites/def...20ISS%2010.pdf Page 15
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Old 14th Aug 2019, 11:09
  #1830 (permalink)  
 
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Originally Posted by safetypee View Post


Apparently the autopilot / auto trim has the ability to trim over full range. This is ambiguous; either as required for autopilot control - stay in trim, but not manual trim cert requirements. Also, this could invalidate the safety inhibition as above - trim is still electrically enabled, and ‘if so’, and ‘if’ MCAS was routed via the ‘auto’ FCC, then it could electrically signal the tail to move in conditions which the stick trim could not.

Reference to ‘aisle stand trim switches’ is confusing, perhaps trim wheel.

https://www.easa.europa.eu/sites/def...20ISS%2010.pdf Page 15
Thank you both for your replies.

So.....it COULD be that MCAS is able to trim the surface beyond the point at which the electric trim switches were inhibited.

Understood that the auto trim should not have been allowed to run that far without 'contradiction, though acknowledging that MCAS drive auto-trim drives the surface ~50% faster than the manual electric trim
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Old 14th Aug 2019, 12:06
  #1831 (permalink)  
 
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I guess we are beyond the "MCAS COULD" - we are pretty sure about that it does.
Having looked at the wiring diagrams it can indeed not be deduced if the only one direction of electric trim is inhibited beyond a certain deflection or both. I assumed it was only the towards mechanical limits direction. Maybe there was some input before in one of the threads but I cannot find it at the moment.
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Old 14th Aug 2019, 15:46
  #1832 (permalink)  
 
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Dave your previous might be misinterpreted on two counts.
‘Flight envelope’ implies an in-trim condition (speed?), whereas if the more likely tech design was that the trim cutout was relative to the tail angle then the crew could encounter very high stick loads relative to that required for the aircraft to be ‘in trim’ at the actual speed.

The reports / FDR did indicate that the crew attempted to use elect trim at larger tail angles, but without movement. Unfortunately there is no indication of this being relative to any elect trim inhibition, not known (or trim direction?), nor if this was due to high mechanical loading or purely elect inhibition.
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Old 14th Aug 2019, 16:02
  #1833 (permalink)  
 
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Originally Posted by safetypee View Post
The reports / FDR did indicate that the crew attempted to use elect trim at larger tail angles, but without movement.
Indeed so. My point was that the crew did not appear to be trying to use electric trim to get further out-of-trim (which is the direction in which the inhibit operates). The crew trim inputs were, as one might expect, in the direction to get the aircraft back in-trim, i.e. ANU:

Originally Posted by DaveReidUK View Post
Besides, there's no suggestion that either crew was attempting to trim in the direction of the extremes of the range.
I probably could have worded that slightly better. How about "there's no suggestion that either crew was attempting to trim in the direction approaching the extremes of the range" ?
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Old 14th Aug 2019, 16:56
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Originally Posted by safetypee View Post
The reports / FDR did indicate that the crew attempted to use elect trim at larger tail angles, but without movement. Unfortunately there is no indication of this being relative to any elect trim inhibition, not known (or trim direction?), nor if this was due to high mechanical loading or purely elect inhibition.
I assume you are talking about the ET302 Preliminary Report. Where does it "indicate that the the crew attempted to use MET at larger tail angles, but without movement"?

The second MCAS activation at 05:40:20 moved the stab trim down to 0.4 units, its lowest point of the flight. Airspeed was just below VMO. The crew responded with MET and raised the stab trim back up to 2.3 units. The two MET blips at the end of the flight (05:43:11) raised the stab trim position from 2.1 to 2.3 units. The switch wasn't held long enough to affect more movement, but that doesn't mean it was "without" movement.

As for the question whether MET can trim up after the stabilizer is beyond the nose-down limit, or trim down after the stabilizer is beyond the nose-up limit, the schematics posted by Yoko1 on June 28 suggest they can (sorry, but I don't seem to be able to reproduce them here b/c I'm still new). The MET trim up signal goes through the stab nose up limit switch, but not the nose down limit switch. Likewise, the MET trim down signal goes through the stab nose down limit switch, but not the nose up limit switch. So, for example, the stabilizer being beyond the nose down limit should have no effect on MET trim up signals.
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Old 14th Aug 2019, 17:27
  #1835 (permalink)  
 
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The schematics posted by the alter ego do only show that there are two seperate inputs to the eaton actuator for nose up and down electric trim end switch. Nothing is disclosed about how they are evaluated and used within the eaton assembly.

Last edited by BDAttitude; 14th Aug 2019 at 17:46.
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Old 14th Aug 2019, 18:11
  #1836 (permalink)  
 
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Originally Posted by BDAttitude View Post
The schematics posted by the alter ego do only show that there are two seperate inputs to the eaton actuator for nose up and down electric trim end switch. Nothing is disclosed about how they are evaluated and used within the eaton assembly.
It is conceivable that the Eaton motor assembly knows the position of the stabilizer (although I've seen no evidence of that). It is a lot harder to believe that Boeing would bake flight dynamics decisions (nose up and down limits and their affects on MET and FCC trim commands) into the motor. Do you have any factual basis for speculating that the Eaton motor inhibits MET signals based on stab position?
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Old 14th Aug 2019, 18:13
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[Not a pilot] After STAB TRIM cutout, the Ethiopian pilots were apparently wondering why the electric trim was not working. After one minute of this, the First Officer requested permission to try manual trim, which would seem to be the handwheel. After eight seconds, he declared that it was not working.

My question: Is it possible that the Pilot in Command flipped only one STAB TRIM cutout switch thinking that it would still allow electric trim as on previous 737s?

I'm not qualified to say how MAIN ELECT and AUTO PILOT work on previous series planes, but might a scenario like this explain the wasted minute until the first officer spoke up?
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Old 14th Aug 2019, 19:35
  #1838 (permalink)  
 
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Originally Posted by fotoguzzi View Post
[Not a pilot] After STAB TRIM cutout, the Ethiopian pilots were apparently wondering why the electric trim was not working. After one minute of this, the First Officer requested permission to try manual trim, which would seem to be the handwheel. After eight seconds, he declared that it was not working.

My question: Is it possible that the Pilot in Command flipped only one STAB TRIM cutout switch thinking that it would still allow electric trim as on previous 737s?

I'm not qualified to say how MAIN ELECT and AUTO PILOT work on previous series planes, but might a scenario like this explain the wasted minute until the first officer spoke up?
Honestly, after reading the transcript several times it is hard for me to clearly determine what the two pilots were trying to communicate. Statements like "trim with me" or "the trim isn't working" don't reference electric vs manual so it isnt obvious what they were talking about or what they assumed to be the condition of the trim system. I'm guessing that English may not have been either pilot's primary language, so it also understandable that under stressful conditions precise terminology was lacking. It has been discussed elsewhere in this and other threads that prior to these accidents, training in Runaway Stab trim and use of manual trimming had been pretty spotty, ironically because the 737 stab trim system had historically been very reliable, so it is also possible that neither pilot had any recent training experience in these procedures. That might explain in part slow reaction times. I'm not in any way a fan of putting video cameras in the cockpit, but I'll admit that this is one time that it would have been helpful.

As far as the functionality of the two switches, procedurally these switches are always used together whether on the NG or MAX and frankly I don't see this crew having either the awareness or the inclination to make this kind of distinction and diverge from procedure and use just one of the switches.
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Old 14th Aug 2019, 21:09
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[Not a pilot]
I have to agree. The two hundred hour pilot did not have any decades long habit of flipping just one switch, and he was the one who threw the switches. Why the Captain was seemingly expecting manual electric still to work is a mystery, which was why I thought they may have thrown only one switch.

"At 05:40:35, the First-Officer called out “stab trim cut-out” two times. Captain agreed and First-Officer confirmed stab trim cut-out."

"At 05:41:46, the Captain asked the First-Officer if the trim is functional. The First-Officer has replied that the trim was not working and asked if he could try it manually. The Captain told him to try."

"At 05:41:54, the First-Officer replied that it is not working."

Not sure if the handwheel would have been easier to turn a minute sooner, but CUTOUT should have been a good hint that manual electric was no longer going to work.

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Old 14th Aug 2019, 23:46
  #1840 (permalink)  
 
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A notice issued by Boeing a long time ago stated that it is okay for both pilots to work the manual trim wheels...dint say why of course.
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