MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures
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Later edit:
That aside, I don't understand what is so controversial in my claim that the post-flight reports of the previous Lion Air crew were lacking. The preliminary report for the Lion Air accident suggests that as well in the "Safety Action" section:
"Lion Air [...] On 30 October 2018, issued information to all pilots which contained reminder to [...] Write on the AFML for any malfunctions that happened during the flight. Brief the engineer on duty comprehensively about the malfunction happened in flight. Please refer to Fault Reporting Manual (FRM) provided in the aircraft. Send report to Safety and Security Directorate through all reporting methods that available as soon as practicable."
"For Operation Directorate To instruct all B737 pilots to use the Fault Reporting Manual (FRM) in all their Aircraft Flight Maintenance Log (AFML) report. This measure shall be enforced by Operations, Training and Standard with immediate effect. To instruct all pilots to fill the AFML report with as much details as deem necessary to provide a full comprehensive description of the technical defect to the engineering team. This measure should be applied with immediate effect."
"For Maintenance Directorate [...] On 3 November 2018, the Chief Pilot issued Notice to Pilot which required all pilots to perform the following: Read and study the FRM (Fault Reporting Manual) and know how to utilize it. Any observed faults, status message, or cabin faults must be written down in the AFML, and ATA Number/Tittle of ECAM Shown (Fault) For A330. Should have any doubt, please contact the chief pilot or Quality Assurance Department via Mission Control (MC) – OM-A 8.6.8. Do not hesitate to describe in details about the defect that has been encountered. This is a good practice especially for the engineers to do the troubleshooting and for the next crew that will fly the aircraft."
Last edited by MemberBerry; 7th Jul 2019 at 00:03.
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Somehow, from the information provided by the aircrew, the technicians were able to figure out that they had a malfunctioning AOA indicator -- which was replaced. The second one failed as well, for reasons that are not known (to us). So from a maintenance point of view, the reports were adequate.
Expecting line technicians in Ethiopia to discover a critical design flaw in a system that Boeing was keeping at least semi-secret is asking too much, in my opinion. Put yourself in the shoes even of a tech working in America, even if you had intimations that the shiny new 737 MAX was completely %$@!$ in rare circumstances and the entire fleet should immediately be grounded, would you pursue that line of inquiry? You have your 18 months of training from a vocational/tech school and you are going up against all of the PhDs at Boeing? I think not...
Expecting line technicians in Ethiopia to discover a critical design flaw in a system that Boeing was keeping at least semi-secret is asking too much, in my opinion. Put yourself in the shoes even of a tech working in America, even if you had intimations that the shiny new 737 MAX was completely %$@!$ in rare circumstances and the entire fleet should immediately be grounded, would you pursue that line of inquiry? You have your 18 months of training from a vocational/tech school and you are going up against all of the PhDs at Boeing? I think not...
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Somehow, from the information provided by the aircrew, the technicians were able to figure out that they had a malfunctioning AOA indicator -- which was replaced. The second one failed as well, for reasons that are not known (to us). So from a maintenance point of view, the reports were adequate.
Expecting line technicians in Ethiopia to discover a critical design flaw in a system that Boeing was keeping at least semi-secret is asking too much, in my opinion. Put yourself in the shoes even of a tech working in America, even if you had intimations that the shiny new 737 MAX was completely %$@!$ in rare circumstances and the entire fleet should immediately be grounded, would you pursue that line of inquiry? You have your 18 months of training from a vocational/tech school and you are going up against all of the PhDs at Boeing? I think not...
Expecting line technicians in Ethiopia to discover a critical design flaw in a system that Boeing was keeping at least semi-secret is asking too much, in my opinion. Put yourself in the shoes even of a tech working in America, even if you had intimations that the shiny new 737 MAX was completely %$@!$ in rare circumstances and the entire fleet should immediately be grounded, would you pursue that line of inquiry? You have your 18 months of training from a vocational/tech school and you are going up against all of the PhDs at Boeing? I think not...
very few PhDs at boeing are managers and real decision makers - they invariably work for some MBA power point ranger who made it up the chain of command. And the software is often nowdays checked by outside contractors who make far less money. At least thats the new ( since 1997 ) Boeing- not the old Boeing...
NG and MAX issues are proof - profit first, second, third priority - if you disagree you are encouraged to spend time with family or spend more time understanding the org chart and why you are not on it .
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In the Lion Air 610 accident flight, the Captain was flying and after the initial "surprise" when MCAS started doing its thing, he recovered nicely and maintained a relatively constant stab position with frequent Main Electric Trim inputs. He then handed the aircraft to the First Officer, and we see the decided inflection point in stab position where the FO effectively dug his own hole. Unfortunately, the Captain wasn't paying sufficient attention...
So again, what was the difference in the training, experience, and/or environment of the first three pilots and the last two that may have explained the dramatic difference in performance? We don't have the information (at least yet), but it is a reasonable line of inquiry.
So again, what was the difference in the training, experience, and/or environment of the first three pilots and the last two that may have explained the dramatic difference in performance? We don't have the information (at least yet), but it is a reasonable line of inquiry.
I'll post the FDR traces link at the end of this post.
At the moment that the PF handed off control of LT610, MCAS was in the MIDDLE of an 11-second run. At the beginning of the hand-off the trim was at roughly 5.2 units, but during the transition to the copilot it dropped to just over three units. Thus the contention that the copiilot took a controllable airplane and screwed it into the ground is just blatantly false.
The resultant of that handoff in mid-MCAS deployment was:
1. The co-pilot's stick forces immediately shot off the charts as he took control of a quickly increasing out-of-trim aircraft and tried to hold the nose up.
2. A (relatively) high negative-G bunt as he took control of a rapidly nose-down trimming airplane.
3. Airspeed began to increase rapidly, increasing stick forces accordingly. (Hmmmm... Where have we seen that phenomenon recently??)
4. Altitude began to decrease rapidly, increasing airspeed, stress, control forces etc.
MCAS continued to make inputs over the remaining 45 seconds or so of the flight yet he made not less than 7 attempts to trim against MCAS inputs, which eventually drove the trim all the way down to nearly zero units. (And which fact blows your entire "he did nuthin'" argument out of the water...) He did something, it just wasn't enough against quickly upsloping stick forces, negative G, increasing airspeed and MCAS "helping" out every five seconds
I wish I could find a way to express well how inappropriate it is to blame the crew for this boondoggle. Placing the blame at the foot of the copilot (and wrapping it in the fig leaves of "training issues") is cruel and pointless and speaks to a moral and technical certitude which is ugly to see expressed anywhere, much less somewhere like PPRuNE, which is (mostly) an outlier of good taste and moderation in an increasingly bananas world. .
Please for the love of god let go of this inane and offensive argument!!
Regards-
dce
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Somehow, from the information provided by the aircrew, the technicians were able to figure out that they had a malfunctioning AOA indicator -- which was replaced. The second one failed as well, for reasons that are not known (to us). So from a maintenance point of view, the reports were adequate.
Expecting line technicians in Ethiopia to discover a critical design flaw in a system that Boeing was keeping at least semi-secret is asking too much, in my opinion. Put yourself in the shoes even of a tech working in America, even if you had intimations that the shiny new 737 MAX was completely %$@!$ in rare circumstances and the entire fleet should immediately be grounded, would you pursue that line of inquiry? You have your 18 months of training from a vocational/tech school and you are going up against all of the PhDs at Boeing? I think not...
Expecting line technicians in Ethiopia to discover a critical design flaw in a system that Boeing was keeping at least semi-secret is asking too much, in my opinion. Put yourself in the shoes even of a tech working in America, even if you had intimations that the shiny new 737 MAX was completely %$@!$ in rare circumstances and the entire fleet should immediately be grounded, would you pursue that line of inquiry? You have your 18 months of training from a vocational/tech school and you are going up against all of the PhDs at Boeing? I think not...
The AoA was replaced before the flight with the Lion Air crew that managed to save the aircraft. And that Lion Air crew that saved the plane didn't report the stick shaker issue. After that flight the engineers/technicians/mechanics at Lion Air (Indonesia) didn't test the recently replaced AoA vane for issues. If the stick shaker would have been reported by the pilots after that flight, engineers/technicians/mechanics might have checked the AoA vane and may have fixed the problem before the accident Lion Air flight (Indonesian).
I didn't expect the engineers/technicians/mechanics at Lion Air (Indonesia) to find any critical flaw about MCAS or the MAX. But just as they replaced the AoA sensor once, at the very least they could replace it a second time. Since the AoA issue and the stick shaker simptom started when they replaced the AoA sensor, replacing it again might have fixed the issue and the Lion Air (Indonesian) accident might not have happened.
None of this assumes or requires any knowledge about MCAS from any of the Lion Air employees. If that's still not clear, maybe somebody else could try to explain it better than me, because I give up.
Last edited by MemberBerry; 7th Jul 2019 at 03:55.
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Once again I have to respectfully state that you are (to use your own vernacular) barking up the wrong tree in your quest to pin this on the crew.
I'll post the FDR traces link at the end of this post.
At the moment that the PF handed off control of LT610, MCAS was in the MIDDLE of an 11-second run. At the beginning of the hand-off the trim was at roughly 5.2 units, but during the transition to the copilot it dropped to just over three units. Thus the contention that the copiilot took a controllable airplane and screwed it into the ground is just blatantly false.
The resultant of that handoff in mid-MCAS deployment was:
1. The co-pilot's stick forces immediately shot off the charts as he took control of a quickly increasing out-of-trim aircraft and tried to hold the nose up.
2. A (relatively) high negative-G bunt as he took control of a rapidly nose-down trimming airplane.
3. Airspeed began to increase rapidly, increasing stick forces accordingly. (Hmmmm... Where have we seen that phenomenon recently??)
4. Altitude began to decrease rapidly, increasing airspeed, stress, control forces etc.
MCAS continued to make inputs over the remaining 45 seconds or so of the flight yet he made not less than 7 attempts to trim against MCAS inputs, which eventually drove the trim all the way down to nearly zero units. (And which fact blows your entire "he did nuthin'" argument out of the water...) He did something, it just wasn't enough against quickly upsloping stick forces, negative G, increasing airspeed and MCAS "helping" out every five seconds
I wish I could find a way to express well how inappropriate it is to blame the crew for this boondoggle. Placing the blame at the foot of the copilot (and wrapping it in the fig leaves of "training issues") is cruel and pointless and speaks to a moral and technical certitude which is ugly to see expressed anywhere, much less somewhere like PPRuNE, which is (mostly) an outlier of good taste and moderation in an increasingly bananas world. .
Please for the love of god let go of this inane and offensive argument!!
Regards-
dce
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I'll post the FDR traces link at the end of this post.
At the moment that the PF handed off control of LT610, MCAS was in the MIDDLE of an 11-second run. At the beginning of the hand-off the trim was at roughly 5.2 units, but during the transition to the copilot it dropped to just over three units. Thus the contention that the copiilot took a controllable airplane and screwed it into the ground is just blatantly false.
The resultant of that handoff in mid-MCAS deployment was:
1. The co-pilot's stick forces immediately shot off the charts as he took control of a quickly increasing out-of-trim aircraft and tried to hold the nose up.
2. A (relatively) high negative-G bunt as he took control of a rapidly nose-down trimming airplane.
3. Airspeed began to increase rapidly, increasing stick forces accordingly. (Hmmmm... Where have we seen that phenomenon recently??)
4. Altitude began to decrease rapidly, increasing airspeed, stress, control forces etc.
MCAS continued to make inputs over the remaining 45 seconds or so of the flight yet he made not less than 7 attempts to trim against MCAS inputs, which eventually drove the trim all the way down to nearly zero units. (And which fact blows your entire "he did nuthin'" argument out of the water...) He did something, it just wasn't enough against quickly upsloping stick forces, negative G, increasing airspeed and MCAS "helping" out every five seconds
I wish I could find a way to express well how inappropriate it is to blame the crew for this boondoggle. Placing the blame at the foot of the copilot (and wrapping it in the fig leaves of "training issues") is cruel and pointless and speaks to a moral and technical certitude which is ugly to see expressed anywhere, much less somewhere like PPRuNE, which is (mostly) an outlier of good taste and moderation in an increasingly bananas world. .
Please for the love of god let go of this inane and offensive argument!!
Regards-
dce
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stop blaming those guys that lost their lives in trying to fly a plane with deaign flaws... and focus on how to fix those design mistakes.. yoko1 i have asked to you a few days ago about your comment on not retracting flaps...and you ignored it... it is way to easy to blame some guys that tried their best to get out of a crap situation created by poor engineering...
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https://www.usatoday.com/story/news/...aa/1641781001/
foreign pilots without skills...that is what american news is now pushing...shame on them
foreign pilots without skills...that is what american news is now pushing...shame on them
the lunatic fringe
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https://www.usatoday.com/story/news/...aa/1641781001/
foreign pilots without skills...that is what american news is now pushing...shame on them
foreign pilots without skills...that is what american news is now pushing...shame on them
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Ah yes, thank you. I see that you are right, media reported that indicators had been repaired but I think it was the airspeed indicators that were replaced. But I still don't see why reporting the stick shaker is the key missing part here, since my understanding is that the stick shaker activates based on airspeed and not AOA. The captain did report that the airspeed indicators were wrong. A technician might have concluded from this information that the recently replaced AOA indicator was the root cause, but for whatever reason he didn't. Hindsight is 20/20.
From the report:
The point that I am trying to convey is that the problem was not one of carelessness or stupidity -- the pilots had a mental model of what caused the failure. The Airspeed indicator was wrong which caused the STS system to run in reverse. This is what they reported to the techs, and this is what the techs tried to solve. The fact that the AOA sensor failure was critical was in nobody's mental model because Boeing had not told anybody about MCAS. In the electronic log, the pilot reported a critical failure that caused him to hand off control to the FO, so I don't really see any dereliction of duty here. According to his mental model of the problem, he reported everything that was wrong with the plane. It is lawyerly to go through and look for some omission that perhaps should have, could have, led to the key insight into the MCAS problem -- and it ignores the fact that had Boeing documented MCAS and the known vulnerability that it has to a duff AOA (not speed) sensor, everybody would have been "in the loop" and the accident would probably not have happened.
From the report:
After parking, the PIC informed the engineer about the aircraft problem and entered IAS (Indicated Air Speed) and ALT (altitude) Disagree and FEEL DIFF PRESS (Feel Differential Pressure) light problem on the Aircraft Flight Maintenance Log (AFML).
The PIC also reported the flight condition through the electronic reporting system of the company A-SHOR. The event was reported as follows:
Airspeed unreliable and ALT disagree shown after takeoff, STS* also running to the wrong direction, suspected because of speed difference, identified that CAPT instrument was unreliable and handover control to FO. Continue NNC of Airspeed Unreliable and ALT disagree. Decide to continue flying to CGK at FL280, landed safely runway 25L.
Note: STS = Speed Trim System
The PIC also reported the flight condition through the electronic reporting system of the company A-SHOR. The event was reported as follows:
Airspeed unreliable and ALT disagree shown after takeoff, STS* also running to the wrong direction, suspected because of speed difference, identified that CAPT instrument was unreliable and handover control to FO. Continue NNC of Airspeed Unreliable and ALT disagree. Decide to continue flying to CGK at FL280, landed safely runway 25L.
Note: STS = Speed Trim System
Last edited by Water pilot; 7th Jul 2019 at 05:47.
https://www.usatoday.com/story/news/...aa/1641781001/
foreign pilots without skills...that is what american news is now pushing...shame on them
foreign pilots without skills...that is what american news is now pushing...shame on them
I think the evidence will be interesting, if all of it is presented.
There have been a number of fatal accidents with very experienced crew and without a doubt there will be more, just where and when is the question.
A current thread on PPRuNE has said that not long ago any "pilot with a pulse" could get a job at a number of USA companies on a E3 visa. Also the progression to captain was extremely fast!
Now add in the overtime (fatigue) to bolster the base pay and an insecure future (no PR option on the E3) and we have a few holes in the American cheese lining up.
I find it interesting that the same folk that are blaming foreign crew training/skill are quiet on computer based training subject.
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Ah yes, thank you. I see that you are right, media reported that indicators had been repaired but I think it was the airspeed indicators that were replaced. But I still don't see why reporting the stick shaker is the key missing part here, since my understanding is that the stick shaker activates based on airspeed and not AOA. The captain did report that the airspeed indicators were wrong. A technician might have concluded from this information that the recently replaced AOA indicator was the root cause, but for whatever reason he didn't. Hindsight is 20/20.
From the report:
The point that I am trying to convey is that the problem was not one of carelessness or stupidity -- the pilots had a mental model of what caused the failure. The Airspeed indicator was wrong which caused the STS system to run in reverse. This is what they reported to the techs, and this is what the techs tried to solve. The fact that the AOA sensor failure was critical was in nobody's mental model because Boeing had not told anybody about MCAS. In the electronic log, the pilot reported a critical failure that caused him to hand off control to the FO, so I don't really see any dereliction of duty here. According to his mental model of the problem, he reported everything that was wrong with the plane. It is lawyerly to go through and look for some omission that perhaps should have, could have, led to the key insight into the MCAS problem -- and it ignores the fact that had Boeing documented MCAS and the known vulnerability that it has to a duff AOA (not speed) sensor, everybody would have been "in the loop" and the accident would probably not have happened.
From the report:
The point that I am trying to convey is that the problem was not one of carelessness or stupidity -- the pilots had a mental model of what caused the failure. The Airspeed indicator was wrong which caused the STS system to run in reverse. This is what they reported to the techs, and this is what the techs tried to solve. The fact that the AOA sensor failure was critical was in nobody's mental model because Boeing had not told anybody about MCAS. In the electronic log, the pilot reported a critical failure that caused him to hand off control to the FO, so I don't really see any dereliction of duty here. According to his mental model of the problem, he reported everything that was wrong with the plane. It is lawyerly to go through and look for some omission that perhaps should have, could have, led to the key insight into the MCAS problem -- and it ignores the fact that had Boeing documented MCAS and the known vulnerability that it has to a duff AOA (not speed) sensor, everybody would have been "in the loop" and the accident would probably not have happened.
• alpha vane angle of attack outputs
• ADIRU outputs
• anti–ice controls
• wing configurations
• air/ground sensing
• thrust
• FMC outputs.
The SMYD computers provide outputs for all stall warning to include stick shaker and signals to the pitch limit indicator and airspeed displays and the GPWS windshear detection and alert.
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If the stick shaker would have been reported by the pilots after that flight, engineers/technicians/mechanics might have checked the AoA vane and may have fixed the problem before the accident Lion Air flight (Indonesian).
I didn't expect the engineers/technicians/mechanics at Lion Air (Indonesia) to find any critical flaw about MCAS or the MAX. But just as they replaced the AoA sensor once, at the very least they could replace it a second time. Since the AoA issue and the stick shaker simptom started when they replaced the AoA sensor, replacing it again might have fixed the issue and the Lion Air (Indonesian) accident might not have happened.
I didn't expect the engineers/technicians/mechanics at Lion Air (Indonesia) to find any critical flaw about MCAS or the MAX. But just as they replaced the AoA sensor once, at the very least they could replace it a second time. Since the AoA issue and the stick shaker simptom started when they replaced the AoA sensor, replacing it again might have fixed the issue and the Lion Air (Indonesian) accident might not have happened.
(b) if you are troubleshooting a problem persisting over several flights (AOA issues did not start with the replaced sensor) do you assume the cause is the part you have replaced with new, or that the cause is more likely elsewhere?
But the bigger problem with the theory that better reporting would help (I think) is that maintenance appear to have their own automation dependency problem. The LionAir guys asked the aircraft (BITE/IFIM) what was broken, fixed that and asked the aircraft if everything was now OK, got a yes = job done, end of thinking.
For a more detailed actual example of why reporting stick shaker would make sod-all difference to the outcome, consider this result of a busted AOA sensor:
* stick shaker at V1
* takeoff, establish stick shaker is spurious
* engage autopilot at 400ft "as normal" (because stick shaker identified as spurious)
* troubleshoot by calling home to find out where the CB is to turn the
shaker off, pull CB* get to FL170 and notice IAS and ALT disagree so run those checklists at that point
* discuss whether or not to continue flight
* decide to land and get maintenance to look at it (note the stick shaker was definitely reported - to find out which CB)
* maintenance use BITE, identify failed ADC, replace ADC, confirm BITE checks out, good to go
* second attempt at takeoff, stick shaker at V1 followed by high speed RTO...
Note that I suggest working out which incident that was before whining about inexperienced or third-world crews or airlines or maintenance...
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What surprises me is that knowing all off these sensors work with a minimal voltage or resistive change , just like in a car.
Bad grounding would ruin the reading of the value so quickly.
Then when i read the report of the Lion air they swap the sensor without investigeting , this is a brand new plane and already the sensor failed , no one thinks that there might be a problem with the wiring from the sensor to the fcc ?
Reminds me of my peugeot 205 there was smoke coming out of the indicator/wiper handle so i replaced it and it fried again because actually the wiring at the rear windscreen wiper was shorted against the frame.
Till now no one has brought up that the failure might have been in the wiring harness.
The maintance guy even cleaned the connector ! did he not know he was working on a brand new airplane ?
BDAttitude and DaveReidUK have followed up on this
Bad grounding would ruin the reading of the value so quickly.
Then when i read the report of the Lion air they swap the sensor without investigeting , this is a brand new plane and already the sensor failed , no one thinks that there might be a problem with the wiring from the sensor to the fcc ?
Reminds me of my peugeot 205 there was smoke coming out of the indicator/wiper handle so i replaced it and it fried again because actually the wiring at the rear windscreen wiper was shorted against the frame.
Till now no one has brought up that the failure might have been in the wiring harness.
The maintance guy even cleaned the connector ! did he not know he was working on a brand new airplane ?
BDAttitude and DaveReidUK have followed up on this
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And others (including me) have questioned if there was missing some sort of signal validation one would assume is state of the art.
The maintenance guy even cleaned the connector ! did he not know he was working on a brand new airplane ?
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BDAttitude DaveReidUK I stand corrected
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This is maintenance magenta line - "feel diif press light" wasn't indicating a fault and wasn't faulty, rather EFS was active for some time which means stick shaker was also, coupled with the reported IAS and ALT disagree should be more than enough to indicate AOA information (not necessarily probe) problem. But the IFIM is obviously not smart enough to work that out, and the spanners were either not smart enough to deviate from it, or were constrained to stick to it. Same goes for trusting the BITE when it said all was ok.
And as for (in another post) why inspect or clean a connector on a brand new aircraft if you were actually thinking rather than doing maintenance-by-numbers - KC46 FOD ring a bell with anyone?
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What surprises me is that knowing all off these sensors work with a minimal voltage or resistive change , just like in a car.
Bad grounding would ruin the reading of the value so quickly.
Then when i read the report of the Lion air they swap the sensor without investigeting , this is a brand new plane and already the sensor failed , no one thinks that there might be a problem with the wiring from the sensor to the fcc ?
Reminds me of my peugeot 205 there was smoke coming out of the indicator/wiper handle so i replaced it and it fried again because actually the wiring at the rear windscreen wiper was shorted against the frame.
Till now no one has brought up that the failure might have been in the wiring harness.
The maintance guy even cleaned the connector ! did he not know he was working on a brand new airplane ?
BDAttitude and DaveReidUK have followed up on this
Bad grounding would ruin the reading of the value so quickly.
Then when i read the report of the Lion air they swap the sensor without investigeting , this is a brand new plane and already the sensor failed , no one thinks that there might be a problem with the wiring from the sensor to the fcc ?
Reminds me of my peugeot 205 there was smoke coming out of the indicator/wiper handle so i replaced it and it fried again because actually the wiring at the rear windscreen wiper was shorted against the frame.
Till now no one has brought up that the failure might have been in the wiring harness.
The maintance guy even cleaned the connector ! did he not know he was working on a brand new airplane ?
BDAttitude and DaveReidUK have followed up on this
The main issue in that case was the maintenance staff were hung out to dry by the diabolical pirep written up by the previous crew. Granted theres nothing been said about what was handed over verbally but with an issue so serious it should have been documented in much more detail, taking several pages of the techlog if required.
And talking of cleaning connectors. You'd be surprised just how often connectors can be contaminated by stray fluids and the like or have a pin that's bent or disengaged so it's always worth a look. Especially with more and more fibre optics in connectors where clean connections are paramount.
It will be interesting to see whether the USA Today piece and the linked Fox News commentary by Sam Graves are the start of a trend, appearing, as they do, as the consensus expectation shifts to a year-end return to flight.