Boeing 737 MAX

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I wonder what the holdup is?

The procedure to safely fly the Max was known (perhaps not well understood) before the accidents.

By now even the 3rd world , 200 hour seat warmers should know how to make the aircraft function should one of the angle of attack sensors fail.

Sure a software fix would make it easier to fly , but today every Max would be safe to operate , and a simulator ride to certify the crews level of understanding might be wise for PR reasons.

So what is the holdup?
 
Why the holdup? It has become political.
 
Ski in NC said:
Why the holdup? It has become political.
Click to expand...

Yep. And a lot of interested entities want their voice heard. They aren't going to risk f*cking it up the second time so they want to make sure everyone is on board before they go forward with the plan.
 
The holdup is it’s an serious aircraft problem not a pilot problem. ( from a first world pilot that has flown the scenario in a Boeing sim).
 
Ski in NC said:
Why the holdup? It has become political.
Click to expand...

The big question is if Boeing was not forthcoming about the MCAS and the FAA did not know, did not care, or just missed it, is what else might be lurking in the MAX that may also have unintended consequences.

There are lots of new systems on the MAX to make it fly better. If the MCAS (which was there for a similar reason) can screw up and lead to a crash, what about the other new stuff?

For instance, there is a new FBW spoiler system. One of the things this does is deploy the spoilers a bit on approach at flap 30 or 40 so the flight spoilers will raise slightly to reduce lift necessitating a higher AOA and hence nose attitude to give an "acceptable nose gear contact margin" (because the wing and landing gear geometry has changed from previous 737 models). I'm not saying it could occur, but what happens if this system puts the spoilers full out, or full out on only one wing? Was this tested? How extensively? Does anyone actually know? Boeing has already shown that they may not have thought things out all the way through. Needless to say, a full spoiler deployment at low altitude at approach speeds is unlikely to have a good outcome.

Basically, the whole certification process on the MAX has been called into question. Boeing is going to have to convince the regulators that the plane is ok and the regulators are going to have to convince the public that they (the regulators) know what they are talking about.

Since the certification of an airplane model takes a minimum of a couple of years (even for a derivative model), going back and reviewing the MAX certification is not going to be a something that is done overnight, even without any defensive finger pointing.

Another issue is foreign regulators (which were the first to ground the MAX). A number of them see the US FAA as the gold standard and say "If it's good enough for the FAA it is good enough for us." If they come to believe that the FAA is out of their depth and not the standard they think it was, there is going to be a whole lot of pain to get these foreign regulators to approve the MAX again because they won't want to rubber stamp the FAA certificate for their country.

This is a worldwide problem for Boeing. Solving it in the US with the US regulators will help their case a lot, but it will not automatically be a free pass everywhere. The majority of MAX orders are to foreign carriers.
 
Virgin Australia, largely owned by foreign airlines and a bit (?10%) by Branson,which bases its domestic fleet on the 737-800, had a Max8 delivery program commencing November. I saw it reported they cancelled/converted the order to the Max 10 due in a couple of years, maybe with taking the Max 8 later. Could have been an issue of needing them or paying,I`m not sure. Qantas/Jetstar is top dog here, Virgin struggles to make a profit,Qantas makes lots and pays good dividends.
Perhaps Boeing has to fix 8s to make 10s, I really don`t know.
But based on the sensible analytical recent posts above, some pilots are due an apology for insults offered on this thread.
 
"The holdup is it’s an serious aircraft problem not a pilot problem."

So is "engine failure , fire ,seperation", but these emergencies are handled routinely.
 
FF said:
"The holdup is it’s an serious aircraft problem not a pilot problem."

So is "engine failure , fire ,seperation", but these emergencies are handled routinely.
Click to expand...

Exactly. And this problem is not able to be handled routinely. The whole point of mcas is to make an airplane that has a design flaw (pitch up stall) fly. When mcas fails, not only do the pilots have to initially fight runaway down trim, they subsequently must fly an aircraft that wants to stall and do it without trim motors. Did you read the AW post about starting with extreme down trim and no assist?

This thing is like the post sully sim. With the benefit of hindsight and lots of tries, half the time you can return to the airport and land. Fortunately, aviation standards look for something better than that.

I would not be surprised if the max 8 is done. Bandaiding a flawed design with software is likely recognized for what it is... a bad design.
 
ssobol said:
The big question is if Boeing was not forthcoming about the MCAS and the FAA did not know, did not care, or just missed it, is what else might be lurking in the MAX that may also have unintended consequences.

There are lots of new systems on the MAX to make it fly better. If the MCAS (which was there for a similar reason) can screw up and lead to a crash, what about the other new stuff?

For instance, there is a new FBW spoiler system. One of the things this does is deploy the spoilers a bit on approach at flap 30 or 40 so the flight spoilers will raise slightly to reduce lift necessitating a higher AOA and hence nose attitude to give an "acceptable nose gear contact margin" (because the wing and landing gear geometry has changed from previous 737 models). I'm not saying it could occur, but what happens if this system puts the spoilers full out, or full out on only one wing? Was this tested? How extensively? Does anyone actually know? Boeing has already shown that they may not have thought things out all the way through. Needless to say, a full spoiler deployment at low altitude at approach speeds is unlikely to have a good outcome.

Basically, the whole certification process on the MAX has been called into question. Boeing is going to have to convince the regulators that the plane is ok and the regulators are going to have to convince the public that they (the regulators) know what they are talking about.

Since the certification of an airplane model takes a minimum of a couple of years (even for a derivative model), going back and reviewing the MAX certification is not going to be a something that is done overnight, even without any defensive finger pointing.

Another issue is foreign regulators (which were the first to ground the MAX). A number of them see the US FAA as the gold standard and say "If it's good enough for the FAA it is good enough for us." If they come to believe that the FAA is out of their depth and not the standard they think it was, there is going to be a whole lot of pain to get these foreign regulators to approve the MAX again because they won't want to rubber stamp the FAA certificate for their country.

This is a worldwide problem for Boeing. Solving it in the US with the US regulators will help their case a lot, but it will not automatically be a free pass everywhere. The majority of MAX orders are to foreign carriers.
Click to expand...

That is a most excellent post!!!
 
BruceK said:
Virgin Australia, largely owned by foreign airlines and a bit (?10%) by Branson,which bases its domestic fleet on the 737-800, had a Max8 delivery program commencing November. I saw it reported they cancelled/converted the order to the Max 10 due in a couple of years, maybe with taking the Max 8 later. Could have been an issue of needing them or paying,I`m not sure. Qantas/Jetstar is top dog here, Virgin struggles to make a profit,Qantas makes lots and pays good dividends.
Perhaps Boeing has to fix 8s to make 10s, I really don`t know.
But based on the sensible analytical recent posts above, some pilots are due an apology for insults offered on this thread.
Click to expand...

Nah....we are the only operator of Max9s and our fleet is grounded as well. It has nothing to do with the "derivative". And no apology necessary. Some people are just know-it-all a******s and can't help it.

Screaming04....not gonna happen. The Max(8) is here to stay....as is the 9 and 10. After all of this scrutiny, it will likely be the safest airplane in the fleet/sky!
 
Baker said:
Screaming04....not gonna happen. The Max(8) is here to stay....as is the 9 and 10. After all of this scrutiny, it will likely be the safest airplane in the fleet/sky!
Click to expand...

You’re probably right... “too big to fail”. That said, I stand by my position that people movers should have rock solid stability. As the middleman in far too many emergencies, there’s enough going on without the added burden of an unstable platform. It’s bound to rear it’s head again eventually.

FF is right on one thing. Standby for the name change.
 
Screaming04 said:
You’re probably right... “too big to fail”. That said, I stand by my position that people movers should have rock solid stability. As the middleman in far too many emergencies, there’s enough going on without the added burden of an unstable platform. It’s bound to rear it’s head again eventually.

FF is right on one thing. Standby for the name change.
Click to expand...

It is not an unstable platform. It has some differences compared to previous variants, which is to be expected. The basis for MCAS was apparently rooted in trying to minimize those differences so the cert process was simpler. An unintended consequence of how the rules are structured.

Obviously it was not done well by Boeing.

But the aircraft is not unstable.

(not a pilot here, but have studied this issue quite a bit)
 
Ski in NC said:
It is not an unstable platform. It has some differences compared to previous variants, which is to be expected. The basis for MCAS was apparently rooted in trying to minimize those differences so the cert process was simpler.(read bandaid) An unintended consequence of how the rules are structured (read bypass new cert rules).

Obviously it was not done well by Boeing.

But the aircraft is not unstable.

(not a pilot here, but have studied this issue quite a bit)
Click to expand...

I'm being a bit loose on "unstable", substitute "built in tendency to pitch up and stall when power is applied".
 
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All aircraft with engines mounted under a low wing tend to pitch up when power is applied. Thrust vector from engines is below center of mass and center of drag. Not unique to the Max.
 
Ski in NC said:
All aircraft with engines mounted under a low wing tend to pitch up when power is applied. Thrust vector from engines is below center of mass and center of drag. Not unique to the Max.
Click to expand...

Apparently the problem with the MAX is that this effect is very pronounced in certain flight conditions and an artificial means of counteracting the pitch effect had to be developed.
 
If I remember correctly, the DC10 used to suffer jammed control lines, crashing planes. The MD11 emerged and all was well. So there is a chance for the Max8 but, the longer they are parked one of 2 scenarios results: They are safe because of the long time taken to achieve a thorough fix OR, the extraordinary time taken implies a very difficult fix and people will remain nervous. I`ve been on one only once, with what I read here,not looking forward to the next.
 
BruceK said:
If I remember correctly, the DC10 used to suffer jammed control lines, crashing planes. The MD11 emerged and all was well. ...
Click to expand...

Actually the MD-11 had its own set of problems. A few of them crashed because they had a tendency for PIO after a bounced landing. This may have been a result of the MD-11 having a much smaller horizontal tail than the DC/MD-10 which was supposed to improve efficiency. This MD-11 problem resulted in mandated training for ALL 121 operators in handling bounced landings, even in aircraft that do not have the same tendency. (FWIW, if the plane bounces you go around.)

Because of the smaller horizontal tail, the MD-11 also had to have a Longitudinal Stability Augmentation System (LSAS) as part of the flight control system which among other things improved the pitch stability.

For instance, "Monte Thames, a retired FedEx pilot, said MD-11s were so notoriously "squirrely" to land that pilots routinely spent extra time in flight simulators practicing how to control the plane. "The MD-11 is one of those planes that can bite you real quick."

If you watch the video of the recent Sukhoi Superjet crash it appears a similar PIO occurred after the first bounce that ended up with a burning plane and 41 people dead.
 
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Thanks ssobol. I`m not going to identify the plane we fly on next.
 
"If I remember correctly, the DC10 used to suffer jammed control lines, crashing planes.""

The case I remember was a DC 10 in Europe that some last min cargo put in the aft cargo bay by unqualified help.

The cargo net was loosened , the stuff installed and the employee did not re fasten the net. Sadly the net buckle was in one of the locking hooks so the employee simply forced the outside handle to the locked position.

The handle operated a micro switch , so the cockpit crew saw the "open" light go out and took off.

AS the aircraft pressurized , the entire cabin floor collapsed , binding the cables.

The crew did not understand the aircraft well enough to realize the auto pilot would have flown the aircraft back to landing.

The modern "switch position " pilot training does have costs.
 
ssobol said:
actually the md-11 had its own set of problems. A few of them crashed because they had a tendency for pio after a bounced landing. This may have been a result of the md-11 having a much smaller horizontal tail than the dc/md-10 which was supposed to improve efficiency. This md-11 problem resulted in mandated training for all 121 operators in handling bounced landings, even in aircraft that do not have the same tendency. (fwiw, if the plane bounces you go around.)

because of the smaller horizontal tail, the md-11 also had to have a longitudinal stability augmentation system (lsas) as part of the flight control system which among other things improved the pitch stability.

For instance, "monte thames, a retired fedex pilot, said md-11s were so notoriously "squirrely" to land that pilots routinely spent extra time in flight simulators practicing how to control the plane. "the md-11 is one of those planes that can bite you real quick."

if you watch the video of the recent sukhoi superjet crash it appears a similar pio occurred after the first bounce that ended up with a burning plane and 41 people dead.
Click to expand...




pio ?
 
(from Google): PIO- Pilot Induced Oscillation- Aircraft has a delay or minimal response to a control input, so when pilot senses his control input did not have desired response, gives even further control input. When AC does respond, it over-reacts and pilot has to give control input in the opposite direction. Net result is AC cycling between the pitch (or other) desired.

My boat at slow speed responds the same to rudder inputs. Turn the rudder, and not much effect. Trick is to make a 5deg change and WAIT. Boat will respond in a few sec. When first teaching my GF to drive, She would keep turning the rudder to like 20deg and when boat did respond, it would overshoot. Had to teach her to turn 5 and WAIT. Heck, I had to teach myself that, but it was several years ago. At high speed, no such issue.
 
Ski in NC said:
(from Google): PIO- Pilot Induced Oscillation- Aircraft has a delay or minimal response to a control input, so when pilot senses his control input did not have desired response, gives even further control input. When AC does respond, it over-reacts and pilot has to give control input in the opposite direction. Net result is AC cycling between the pitch (or other) desired.

My boat at slow speed responds the same to rudder inputs. Turn the rudder, and not much effect. Trick is to make a 5deg change and WAIT. Boat will respond in a few sec. When first teaching my GF to drive, She would keep turning the rudder to like 20deg and when boat did respond, it would overshoot. Had to teach her to turn 5 and WAIT. Heck, I had to teach myself that, but it was several years ago. At high speed, no such issue.
Click to expand...


Thanks.
 
Ski in NC said:
My boat at slow speed responds the same to rudder inputs. Turn the rudder, and not much effect. Trick is to make a 5deg change and WAIT. Boat will respond in a few sec. When first teaching my GF to drive, She would keep turning the rudder to like 20deg and when boat did respond, it would overshoot. Had to teach her to turn 5 and WAIT. Heck, I had to teach myself that, but it was several years ago. At high speed, no such issue.
Click to expand...

On the Prairie 29 I used to own, I used to call the steering wheel(helm) the "requestor". Because it took a while for your input to register and sometimes it would not register at all!!!
 
FF said:
"If I remember correctly, the DC10 used to suffer jammed control lines, crashing planes.""

The case I remember was a DC 10 in Europe that some last min cargo put in the aft cargo bay by unqualified help.

The cargo net was loosened , the stuff installed and the employee did not re fasten the net. Sadly the net buckle was in one of the locking hooks so the employee simply forced the outside handle to the locked position.

The handle operated a micro switch , so the cockpit crew saw the "open" light go out and took off.

AS the aircraft pressurized , the entire cabin floor collapsed , binding the cables.

The crew did not understand the aircraft well enough to realize the auto pilot would have flown the aircraft back to landing.

The modern "switch position " pilot training does have costs.
Click to expand...

The Turkish DC-10 crash in Paris was the result of the aft cabin floor collapsing and jamming the control cables for the elevator due to the cargo door latching design. The crew almost figured it out that by using the throttles they might be able to control the plane.

There was another near accident 19 mos before the Turkish crash for the same reason. The problem with the door and the control cable routing and floor collapses was a known issue.

"This possibility of a catastrophic failure as a result of this overall design was first discovered in 1969, and actually occurred in 1970 in a ground test. Although Convair, the contracted manufacturer of the door, informed McDonnell-Douglas of the potential problem, Douglas ignored these concerns, because rectification of what Douglas considered to be a small problem with a low probability of occurrence would have seriously disrupted the delivery schedule of the aircraft, and caused Douglas to lose sales."
 
"built in tendency to pitch up and stall when power is applied". "built in tendency to pitch up and stall when power is applied". This is NORMAL.

The Max problem is that with the engines located under the wing at high very angles of attack the bottom of the nacelle is exposed to the air flow , causing more pitch up than normal.

The Max fancy system was to solve the difference , but an angle of attack sensor failed and the entire "automatic" system to pitch down had far too much authority. Now corrected.

Anyone work out the cost of one days interest on a $150,000,000 aircraft sitting idle?
 
It will be interesting to watch and see how China and Air Bust attempt to drag out the re launch of the Max.

China uses any weapon to harm the US economy in its WTO battle , and Air Bust profits by selling more hulls while Boeing is grounded.

Some think it will be 1st quarter of 2020 before Boeing gets the OK.
 
FF said:
It will be interesting to watch and see how China and Air Bust attempt to drag out the re launch of the Max.

China uses any weapon to harm the US economy in its WTO battle , and Air Bust profits by selling more hulls while Boeing is grounded.

Some think it will be 1st quarter of 2020 before Boeing gets the OK.
Click to expand...

What makes you think that China will intentionally drag out the relaunch of the MAX?

China airlines are a major customer of the MAX (and most other Boeing models). Boeing just opened a completion center near Shanghai for Chinese deliveries.

The Chinese airlines are suffering from the grounding of the MAX like everyone else.

As for Airbus, yes they are a competitor and are happy that Boeing is having problems, but Boeing does not need any sort of approval from Airbus to relaunch the MAX.
 
The entire hassle is the pilots that followed the proper procedure for a run away stabilizer , a memory item, simply turned off 2 switches on the console , and used the trim hand wheel to fly onto their destinations.

Seems they are jumping thru thru lots of hoops to make the aircraft simpler to operate , for folks that cant be bothered to follow existing procedures.
 
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I think saying the pilots messed up, and everyone should get flying again with new training is just an incomplete assessment.


And it's equally incomplete to say it is just a defective plane design.


The pilots did the right things based on what they knew, but they let the air speed get out of control causing the right things to no longer work.


But the pilots were not aware how far the MCAS could trim the plane down, nor how to continually counteract it with the trim switches.


And normal procedures to overcome high manual trim resistance were not available to them because they were too close to the ground.


And MCAS should not have as much command as it does. It's claimed to be a flight characteristic compensator, but it has way more authority that such a system needs, and as a result when operating improperly it can do very bad things.


And something with as much authority as MCAS has, shouldn't be without dual inputs and disagree alarms.


And something with as much authority as MCAS should be well communicated to pilots so they understand what it can do and when it can do it, how it can go wrong, with accompanying training. Especially when it's single input.


And something with the authority of MCAS should have it's own disable capability without also disabling other important and functional things like electric trim.


And the certification process should have caught these discrepancies and triggered corrective actions on some or all of these issues.


So lots of holes to plug, lots of corrective action required, and lots to contemplate about a system that got us here. For better or worse, this is how we learn.
 
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