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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 16th Jul 2019, 02:05
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Originally Posted by SamYeager
As far as MCAS is concerned my gut feeling is that Boeing will stick with a software solution supplemented as necessary by training. However should they go down the route of aero changes I'm curious how much that might affect the claimed fuel savings for the MAX. Any ideas?
Micro VGs on the outboard slats would add a slight drag rise in the cruise, but that could also be offset if acting on the cross flow instabilities near the winglet-wing transition. A couple of biz jets have found benefit in that area.

Strake mods could go either way as well, Reducing or removal of the strakes would adversely affect TODR, but may actually improve cruise drag, if strut-nacelle-wing interference is worked on near the rear of the nacelle.

Tabs and wedges can improve cruise drag, however as the use of those would be to alter Cm at high AOA, the residual effect at low AOA would add to a cruise drag penalty from trim drag. That is able to be offset in part or fully by the flow improvements that occur from the transonic effects of the device itself.

Aft strakes have been used successfully on numerous aircraft, the Lear is the poster child for those. Cruise drag can be improved by their use dependent on design. They alter both directional and longitudinal stability. As a modern device, they are as recent as the DH-82 Tigermoth, would look right at home on a canary yellow B737 with roundels.

Bottom line is, make lemonade from lemons.



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Old 16th Jul 2019, 04:29
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Originally Posted by Takwis
It's best to get it as right as possible without the aerodynamic band aids, of course. But I'd stake my life on metal bits over lines of code any day.
And then you'd only be left with the manual trim wheel issue.....
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Old 16th Jul 2019, 04:57
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Ryanair 737 8200

Looks like Ryanair is shying off the "MAX" name, wonder about others...

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Old 16th Jul 2019, 06:24
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Originally Posted by john_tullamarine
Is not any longitudinal SAS a pitch feel modifier ? ..
Yes but that's a side effect, not necessarily beneficent, especially if the SAS is installed to deal with dynamic (oscillatory) stability issues.

Originally Posted by john_tullamarine
inadequate pitch forces being the reason for SAS in the first place ?
Not the reason. A symptom. Now, what could be the underlying cause for either manual or powered-cum-synthetic-feel pitch controls to go flabby?

Originally Posted by john_tullamarine
I concur with the inference that the anti-stall call was a media mis-hype mistake.
I'm actually inferring that there is good chance the media got it right this time
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Old 16th Jul 2019, 09:28
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Originally Posted by krismiler
A properly designed aircraft shouldn’t require all these aerodynamic add ons, get it right in the first place and you won’t need to go sticking pieces of metal everywhere.
It is a very rare airplane that doesn't need some fixes here or there. VG, vanes, strakes, fences, leading edge "dog tooth" or droop are very common to provide adequate behavior within the whole flight envelope.
For reasons of their own, Boeing chose the quick-and-dirty software patch way.

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Old 16th Jul 2019, 11:06
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I presume that all work done on an aerodynamic solution during development of the MAX, was tempered by a constant consideration of whether or not a new certification would be required, which would certainly hamper a full and frank investigation of all options. Add to that, potential negative effects on fuel economy, and you can start to see why Boeing was strongly drawn to MCAS as a solution.

As far as the trim wheel issue is concerned, this will probably need to be resolved by added redundancy in any ‘powered trim’ system. Retrofitting larger diameter trim wheels or placing a minimum strength requirement on flight crew are both non-starters.
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Old 16th Jul 2019, 11:09
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Originally Posted by Speed of Sound

As far as the trim wheel issue is concerned, this will probably need to be resolved by added redundancy in any ‘powered trim’ system. Retrofitting larger diameter trim wheels or placing a minimum strength requirement on flight crew are both non-starters.
I suspect you are right, though note that this solution will need to be applied to the NG also, and that all the checklists that require use of the trim wheel will need to be rewritten and training provided.
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Old 16th Jul 2019, 11:29
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This. Exactly this. Now that Boeing has publicly stated that they won't go the aerodynamic fix route, they have dug themselves a deep hole.
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Old 16th Jul 2019, 11:30
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Originally Posted by Maninthebar
I suspect you are right, though note that this solution will need to be applied to the NG also, and that all the checklists that require use of the trim wheel will need to be rewritten and training provided.
Rewriting two checklists and half an hour in the simulator will be nothing compared to installing 7,000+ trim servos to the existing NG fleet. I presume that this will be phased in and mandated to be completed by a set date rather than seeing the entire NG fleet grounded which would be political and economic dynamite in the US..
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Old 16th Jul 2019, 12:19
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Originally Posted by Speed of Sound


Rewriting two checklists and half an hour in the simulator will be nothing compared to installing 7,000+ trim servos to the existing NG fleet. I presume that this will be phased in and mandated to be completed by a set date rather than seeing the entire NG fleet grounded which would be political and economic dynamite in the US..
Interesting to note that in previous posts on many of the MAX threads - The B737 manual trim wheel was "marginal" on the classics. They said stab trim was a issue back then and basically never let it get away or your in trouble.

So Boeing have known about it for along time, but chose never to fix it but make it more "marginal" to control on the NG & MAX.
30 years+ to fix, or ground all for 2 years? Guess that's a management call.

Personally ground them if the wheel can not be turned (and Boeing knew) within the envelope.
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Old 16th Jul 2019, 13:07
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Ryanair will stop flying to some airports because of the Boeing 737 Max crisis

London (CNN Business)Ryanair is taking the knife to its operations in Europe as it prepares for two years of disruption caused by Boeing's 737 Max debacle.
Europe's biggest low-cost airline said Tuesday that it was planning to cut back operations at some airports and abandon others entirely because regulators may not return the grounded 737 Max to service until December."We are starting a series of discussions with our airports to determine which of Ryanair's underperforming or loss making bases should suffer these short term cuts and/or closures from November 2019," it said in a statement.

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Old 16th Jul 2019, 13:07
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Originally Posted by Bend alot
.
Personally ground them if the wheel can not be turned (and Boeing knew) within the envelope.
This isn’t simply a matter of physical strength of an individual pilot.If a scenario exists where both flight crew members need to have a hand on each wheel/wheel handle to re-trim the aircraft, this will seriously degrade cockpit resources at a time of already high workload.
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Old 17th Jul 2019, 01:10
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Originally Posted by Speed of Sound


Rewriting two checklists and half an hour in the simulator will be nothing compared to installing 7,000+ trim servos to the existing NG fleet. I presume that this will be phased in and mandated to be completed by a set date rather than seeing the entire NG fleet grounded which would be political and economic dynamite in the US..
For the NG there is probably an out by revising the checklist to re-incorporate the use of 2 (auto and all) cutout switches.

Can probably make the case that non auto instigated trim runaway is very unlikely (common english, not attempting to use certification levels) so having manual electric trim available would suffice.
The service history would also support this.

For MAX this would also require modifying the cutout switches to revert to NG functionality. Although a HW mod it would be trivial compared to adding extra power assist or even mechanical tweaks (foldout ratchets etc) to wheel.

Have to say I do like the image of the battery operated drills coming to the rescue
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Old 17th Jul 2019, 02:09
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Originally Posted by MurphyWasRight

Have to say I do like the image of the battery operated drills coming to the rescue
So do some of us ;-)
For some reasons the relevant posts were deleted.

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Old 17th Jul 2019, 17:03
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If the fix goes beyond software, which looks increasingly likely, they also have to explain why the.NG (same stabiliser, same trim wheel) is OK to very sceptical regulators.....
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Old 17th Jul 2019, 22:10
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Originally Posted by SLF3
If the fix goes beyond software, which looks increasingly likely, they also have to explain why the.NG (same stabiliser, same trim wheel) is OK to very sceptical regulators.....
There was some consensus on here a couple of months ago that any ‘ungrounding’ would be co-ordinated between major regulators. This was before the difficulties with the trim wheel operation and the microprocessor overload issues came to light. I still believe that some form of joint ungrounding will take place but will be after some interesting discussions which will inevitably prolong the process.
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Old 17th Jul 2019, 23:49
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Originally Posted by Speed of Sound
I still believe that some form of joint ungrounding will take place but will be after some interesting discussions which will inevitably prolong the process.
Maybe it is not the discussion that will prolong the process, but rather fixing the issues raised by "other" agencies.
Bad habits die hard, and the FAA might be tempted to overlook some of them, for the sake of national industry.
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Old 18th Jul 2019, 08:49
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Originally Posted by MurphyWasRight
For the NG ....
Can probably make the case that non auto instigated trim runaway is very unlikely (common english, not attempting to use certification levels) so having manual electric trim available would suffice.
No doubt that the operational statistics on the NG prove that this is very unlikely.
My concern is that the system have over achieved in the sense that the low runaway rate is not a result of the Design Assurance Level (DAL C instead of A), but undocumented good engineering :-) This can have unexpected consequences that a minor design update (e.g. the trim motor drive electronics, or implementing MCAS) can change the statistics drastically, despite being within specified limits.
The risk of a trim runaway to it’s stops, is the combined risk of trim system falling, and the pilots falling to react correctly in time.

CS 25 paragraphs 671/672 does not include the possibility of including the pilots reaction time into the equation.
Either the system by design have a low failure rate.
Or the pilots must be able to handle a full runaway without requiring exceptional piloting skill or strength.
It does however not exclude the solution of flipping switches to engage a standby/alternate system.
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Old 18th Jul 2019, 08:54
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The problem is not so much how often it has been required but that it is used as a mitigation in the hierarchy of risk for the airframe.

If it has been demonstrated that the device cannot be used to perform the risk control as stated then EITHER the risk has to be entirely reassessed, another control put in or the trim wheel re-engineered.

If the risk assessment for the NG (and MAX) is unchanged from previous versions for the elements of flight for which the manual trim wheel is a control then the assessments for these will also have to be redone or another control put in.

Either way a big big task for Boeing and regulatory authorities.

Last edited by Maninthebar; 18th Jul 2019 at 10:30.
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Old 18th Jul 2019, 23:20
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"...pretty soon you're talking real money..."

https://www.seattletimes.com/busines...max-grounding/
Boeing faces largest loss in its history after a $4.9 billion financial hit due to 737 MAX grounding

July 18, 2019 at 2:02 pm Updated July 18, 2019 at 3:55 pm
Dominic Gates By Dominic Gates
Seattle Times aerospace reporter

Ahead of its official quarterly earnings release next week, Boeing on Thursday bit the bullet and announced a huge $4.9 billion after-tax accounting charge due to the financial impact of the 737 MAX grounding.

This big cut to earnings will produce Boeing’s first quarterly loss in ten years. Prior to the announcement, S&P Capital IQ had projected a second-quarter profit of $1.3 billion, which will now turn into a loss of around $3.6 billion, the largest loss in Boeing history.

The last time Boeing recorded a net loss was the third quarter of 2009, when it lost $1.6 billion after writing off three flight test 787 Dreamliners and taking a charge for delays on the 747-8.

The charge was recognized in expectation that penalties for late deliveries and other costs will continue over a number of years, even assuming that regulators clear the MAX to fly again in early fall.

In addition to that one-time charge, Boeing also increased its estimated costs to produce the 737 by $1.7 billion in the second quarter, primarily due to the reduced production rate.

That means that this amount will be added to the cost of manufacturing the 737, spread out over the assumed number of 737s remaining to be built, which for accounting purposes is just over 3,000 aircraft.
Boeing similarly added $1 billion to the 737 production costs last quarter because of the reduced production. The combined $2.7 billion addition to the costs will reduce the profit margin on each future 737 delivery and cut the cash flow per aircraft delivered by $900,000.

Boeing said that the charge to earnings will cut its quarterly revenue and pre-tax profits by $5.6 billion.

It added that although this charge is being taken now, the potential concessions to customers or penalties paid will be provided over a number of years and will take various forms of economic value. For example, an airline could potentially choose to take a big discount on a future order or maintenance support rather than upfront money.

That means most of the impact on cash flow will occur in the future.

The charge focuses on the impact of the grounding and does not include any estimate of the financial liability Boeing will incur as a result of the two 737 MAX crashes that killed 346 people, which potentially could be in the region of $3 billion, though much of that may be paid by insurers.

Boeing Chairman and Chief executive Dennis Muilenburg, in a statement, said, “The MAX grounding presents significant headwinds and the financial impact recognized this quarter reflects the current challenges and helps to address future financial risks.”

In arriving at the multibillion-dollar charge figure, Boeing said it “assumed approval of 737 MAX return to service in the U.S. and other jurisdictions begins early in the fourth quarter 2019. This assumption reflects the company’s best estimate at this time, but actual timing of return to service could differ from this estimate.”

Boeing further assumed a gradual increase in the 737 production rate from the current reduced rate of 42 jets per month up to 57 jets per month in 2020, and that airplanes produced during the grounding will be delivered over several quarters following return to service.

“Any changes to these assumptions could result in additional financial impact,” Boeing cautioned.

Ron Epstein, aerospace analyst with Bank of America Merrill Lynch, said that since Boeing’s assumption is that the MAX returns to service “early in the fourth quarter,” which is a six-month grounding, then that projects roughly $1 billion per month in pre-tax penalties paid to customers and about $1.7 billion per quarter added to the 737 cost basis.

But clearly there’s a risk that the timeline for the 737 MAX to return to service could slip, potentially into January 2020, according to the latest pessimistic reports. Epstein said that could add another $3 billion charge and an additional $1.7 billion to the cost basis for 737 accounting.

Before the announcement of the charges, Boeing shares had slipped during market trading Thursday by $8.41 or 2.3 percent. After the announcement, in after-hours trading, investors reacted to the news by buying Boeing stock and three hours later had recovered $6.67 of that loss in value.

Epstein said that’s because some investors will see Boeing’s announcement as taking a big charge to cover the worst case scenario. “They’ll say, this is it, this is as bad as it will be. Now we know the risk.”

He said that because additional delay in returning the MAX to service is possible, it’s unclear if this is in fact as bad as it will be for Boeing. Furthermore, he said, these charges take no account of potential longer-term consequences, such as whether Boeing will lose market share to Airbus in the single-aisle jet market.

Dominic Gates: 206-464-2963 or [email protected]; on Twitter: @dominicgates.
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