Indonesian aircraft missing off Jakarta
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Lion air fights back
28/11/2018 noon
KNKT :"In our view, the plane was not airworthy and should not have kept flying"
straitstimes.com/asia/se-asia/lion-air-plane-not-fit-to-fly-says-safety-agency
28/11/2018 night
Lion air :" We find an incompatibility between the National Transportation Safety Committee`s preliminary report and news contents published by several local media"
"there were media reports informing that the Lion Air plane that crashed into the Java Sea on Oct 29 had not been able to fly normally since its flight from the resort island of Bali to Jakarta on Oct 28.This statement is not true,"
Lion air file a request for the KNKT`s clarification to find whether or not the statement was made by the committee`s credible sources. If the KNTK failed to respond to Lion Air`s written clarification, the airline company would take a legal action
en.antaranews.com/news/120897/lion-air-requests-national-transportation-safety-committees-clarification
29/11/2018
KNKT :“The plane was airworthy during its departure from Denpasar, Bali, under flight number JT043 and its departure from Jakarta under flight number JT610,” as contained in the release, which further negates rumors that the plane’s airworthiness was to be questioned."
That same rumor was also denied by Lion Air as its carrier and maintains that the unit was good to go and corresponds with existing documents based on the Aircraft Fligt Maintenance Log (AFML) passed by the carrier’s engineers that act as releasemen.
The releaseman had conducted a series of tests and checked the reportedly faulty instruments as it landed in Jakarta. The AFML was then signed by the engineers since they deemed that the technical issues had been fixed.
en.tempo.co/read/news/2018/11/29/056923857/KNKT-issue-Report-on-Lion-Airs-JT-610-Airworthiness
28/11/2018 noon
KNKT :"In our view, the plane was not airworthy and should not have kept flying"
straitstimes.com/asia/se-asia/lion-air-plane-not-fit-to-fly-says-safety-agency
28/11/2018 night
Lion air :" We find an incompatibility between the National Transportation Safety Committee`s preliminary report and news contents published by several local media"
"there were media reports informing that the Lion Air plane that crashed into the Java Sea on Oct 29 had not been able to fly normally since its flight from the resort island of Bali to Jakarta on Oct 28.This statement is not true,"
Lion air file a request for the KNKT`s clarification to find whether or not the statement was made by the committee`s credible sources. If the KNTK failed to respond to Lion Air`s written clarification, the airline company would take a legal action
en.antaranews.com/news/120897/lion-air-requests-national-transportation-safety-committees-clarification
29/11/2018
KNKT :“The plane was airworthy during its departure from Denpasar, Bali, under flight number JT043 and its departure from Jakarta under flight number JT610,” as contained in the release, which further negates rumors that the plane’s airworthiness was to be questioned."
That same rumor was also denied by Lion Air as its carrier and maintains that the unit was good to go and corresponds with existing documents based on the Aircraft Fligt Maintenance Log (AFML) passed by the carrier’s engineers that act as releasemen.
The releaseman had conducted a series of tests and checked the reportedly faulty instruments as it landed in Jakarta. The AFML was then signed by the engineers since they deemed that the technical issues had been fixed.
en.tempo.co/read/news/2018/11/29/056923857/KNKT-issue-Report-on-Lion-Airs-JT-610-Airworthiness
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Boeing needs to write a new checklist specifically for MCAS and/or redesign the system. I'll leave it to their engineers and pilots to figure out what should/should not be included. We don't have enough information to make informed decision. Boeing's actions to the point in time are not acceptable. Withholding information about this system is detestable corporate malfeasance.
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The pilots on lion 610 were in regular contact with ATC and as late as 20 seconds before impact with the ocean they indicated their preferred flight level. This suggests they were not under duress in operating the aircraft until the very end. It is still very much unclear why their successful and consistent NU trim corrections are suddenly insufficient to counteract MCAS.
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Obviously not. If I've got active an active stick shaker, I don't need a checklist to tell me not to fly high AoA or Steep Turns and to LAND. That was my (inferred) point. To their credit, at least THIS crew FLEW THE PLANE.
Boeing needs to write a new checklist specifically for MCAS and/or redesign the system. I'll leave it to their engineers and pilots to figure out what should/should not be included. We don't have enough information to make informed decision. Boeing's actions to the point in time are not acceptable. Withholding information about this system is detestable corporate malfeasance.
Boeing needs to write a new checklist specifically for MCAS and/or redesign the system. I'll leave it to their engineers and pilots to figure out what should/should not be included. We don't have enough information to make informed decision. Boeing's actions to the point in time are not acceptable. Withholding information about this system is detestable corporate malfeasance.
If your automatic stab trim is trimming down when you don't want it to. And even after you trim back up it starts trimming nose down again. and you repeat the sequence a couple more times... . even without a NNC checklist it would seem appropriate to switch the automated trim off. That is what the switches are for after all. Even if all you knew about the systems was a black box it is the aviator approach. The previous crew seemed to crack it - but the crash crew didn't - but they had gone through that sequence of auto trim down - manual electric trim up multiple times. So they knew what was happening and how it was counteracted. For some reason they didn't switch the auto stab trim off. I would really like to know where that flying spanner was, as this looks like a fault finding exercise gone wrong rather than set the systems safe and land.
The pilots on lion 610 were in regular contact with ATC and as late as 20 seconds before impact with the ocean they indicated their preferred flight level. This suggests they were not under duress in operating the aircraft until the very end. It is still very much unclear why their successful and consistent NU trim corrections are suddenly insufficient to counteract MCAS.
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A little strong.
If your automatic stab trim is trimming down when you don't want it to. And even after you trim back up it starts trimming nose down again. and you repeat the sequence a couple more times... . even without a NNC checklist it would seem appropriate to switch the automated trim off. That is what the switches are for after all. Even if all you knew about the systems was a black box it is the aviator approach. The previous crew seemed to crack it - but the crash crew didn't - but they had gone through that sequence of auto trim down - manual electric trim up multiple times. So they knew what was happening and how it was counteracted. For some reason they didn't switch the auto stab trim off. I would really like to know where that flying spanner was, as this looks like a fault finding exercise gone wrong rather than set the systems safe and land.
If your automatic stab trim is trimming down when you don't want it to. And even after you trim back up it starts trimming nose down again. and you repeat the sequence a couple more times... . even without a NNC checklist it would seem appropriate to switch the automated trim off. That is what the switches are for after all. Even if all you knew about the systems was a black box it is the aviator approach. The previous crew seemed to crack it - but the crash crew didn't - but they had gone through that sequence of auto trim down - manual electric trim up multiple times. So they knew what was happening and how it was counteracted. For some reason they didn't switch the auto stab trim off. I would really like to know where that flying spanner was, as this looks like a fault finding exercise gone wrong rather than set the systems safe and land.
Re #1791, - Realbabilu
Lion Air have a valid point. If all necessary rectification actions had been taken, and systems checked, then there is no way to identify an ‘unairworthy’ aircraft.
Operators do not ground aircraft every time that they encounter ‘ground tested, no fault found’.
Although there was a history with this aircraft, it is reported that there were intervening flights without problems - only the last two faults were consecutive, (if so why - faulty system resetting / intermittent), and not the exactly the same symptoms being reported after each flight (but probably the same insidious fault), then the operator had reasonably exhausted all ground work.
The debatable point is whether to air test vs ‘check next flight and report’; again compare this with industry practice for intermittent fault finding; EFIS display and stick shake, associated with a recorded AoA fault log, and less than compelling evidence of a trim problem; all of which had been addressed by maintenance action, probably justifies ‘check next flight’, irrespective of an onboard engineer - would he have twigged the significance of trim. Also after one flight a pilot erroneously related the AoA / air data problems with STS, ‘they accounted for the trim going backwards’.
In fact there was no trim problem, it worked as designed; it’s just that this design was not communicated to pilots (would there have been a checklist for failures at this time - before the accident), it would be impossible to describe the exact nature of issue to maintenance. Thus without a description, nor understanding of the likely severity of the malfunction, neither pilots or maintenance could be expected to do better; no better that the regulatory authorities or even Boeing in recognising the hazard.
Lion Air have a valid point. If all necessary rectification actions had been taken, and systems checked, then there is no way to identify an ‘unairworthy’ aircraft.
Operators do not ground aircraft every time that they encounter ‘ground tested, no fault found’.
Although there was a history with this aircraft, it is reported that there were intervening flights without problems - only the last two faults were consecutive, (if so why - faulty system resetting / intermittent), and not the exactly the same symptoms being reported after each flight (but probably the same insidious fault), then the operator had reasonably exhausted all ground work.
The debatable point is whether to air test vs ‘check next flight and report’; again compare this with industry practice for intermittent fault finding; EFIS display and stick shake, associated with a recorded AoA fault log, and less than compelling evidence of a trim problem; all of which had been addressed by maintenance action, probably justifies ‘check next flight’, irrespective of an onboard engineer - would he have twigged the significance of trim. Also after one flight a pilot erroneously related the AoA / air data problems with STS, ‘they accounted for the trim going backwards’.
In fact there was no trim problem, it worked as designed; it’s just that this design was not communicated to pilots (would there have been a checklist for failures at this time - before the accident), it would be impossible to describe the exact nature of issue to maintenance. Thus without a description, nor understanding of the likely severity of the malfunction, neither pilots or maintenance could be expected to do better; no better that the regulatory authorities or even Boeing in recognising the hazard.
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A little strong.
If your automatic stab trim is trimming down when you don't want it to. And even after you trim back up it starts trimming nose down again. and you repeat the sequence a couple more times... . even without a NNC checklist it would seem appropriate to switch the automated trim off. That is what the switches are for after all. Even if all you knew about the systems was a black box it is the aviator approach. The previous crew seemed to crack it - but the crash crew didn't - but they had gone through that sequence of auto trim down - manual electric trim up multiple times. So they knew what was happening and how it was counteracted. For some reason they didn't switch the auto stab trim off. I would really like to know where that flying spanner was, as this looks like a fault finding exercise gone wrong rather than set the systems safe and land.
If your automatic stab trim is trimming down when you don't want it to. And even after you trim back up it starts trimming nose down again. and you repeat the sequence a couple more times... . even without a NNC checklist it would seem appropriate to switch the automated trim off. That is what the switches are for after all. Even if all you knew about the systems was a black box it is the aviator approach. The previous crew seemed to crack it - but the crash crew didn't - but they had gone through that sequence of auto trim down - manual electric trim up multiple times. So they knew what was happening and how it was counteracted. For some reason they didn't switch the auto stab trim off. I would really like to know where that flying spanner was, as this looks like a fault finding exercise gone wrong rather than set the systems safe and land.
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https://www.usatoday.com/story/trave...ts/2138115002/
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No. Not at all. there is nothing to suggest that their airspeed decayed, and a lot of evidence (FDR airspeed and ground speed and ADS-B Groundspeed, all consistent) whcih indicates that it did *not* decay.
Perhaps TOO harsh... but which is worse: a crew that failed to aviate or a troubleshooting excursion with passengers and a flying spanner? ATM the flying spanner has been relegated to a footnote in report appendix. Maybe someone isn't being forthright about this person's role? It should be known by now if he was on the flight for positioning, pleasure or some other purpose.
That would seem to indicate deadheading/positioning and imply a seat in the cabin, though there's no evidence offered either way for that.
Once the CVR is found, if it emerges that the engineer was in fact in the jumpseat, then that will likely also reveal whether they were either just there as a courtesy, or in an observer/troubleshooting role. If the latter, it's very hard to believe they were doing so on their own initiative and almost certain that someone higher up the management chain would have authorised/instructed their presence up front.
STABILIZER TRIM MOTOR CONFIGURATION
I found the following Bulletin in an FCOM for a Classic. It details the different operation of the stabilizer trim main electric motor (turns in only one direction and drives the stabilizer trim actuator through two electro-magnetic clutches, one for NU, another for ND) and the autopilot trim system (turns in either direction and drives the stabilizer trim through a single clutch).
I'm assuming that MCAS commands the AP motor. I'm not an engineer but that arrangement would seem to create the potential for an interesting battle between one motor driving through a single clutch and the other motor driving through the repeated engagement of an electro-magnetic clutch. You might expect that the more efficient configuration will eventually win out over the less efficient in an extended duel, particular if the more efficient configuration is also driving at a faster rate.
The stuck clutch issue described in the bulletin might also be relevant.
Does anyone know if that described motor/clutch arrangement has been carried on through the NG/MAX line?
Would an engineer care to comment on how a duel between the two systems might play out?
PS. The bulletin tends to support one trim wheel rotation = 0.1 units of trim (... the stabilizer trim wheel coasted up to 40 turns (four units of trim).)
I'm assuming that MCAS commands the AP motor. I'm not an engineer but that arrangement would seem to create the potential for an interesting battle between one motor driving through a single clutch and the other motor driving through the repeated engagement of an electro-magnetic clutch. You might expect that the more efficient configuration will eventually win out over the less efficient in an extended duel, particular if the more efficient configuration is also driving at a faster rate.
The stuck clutch issue described in the bulletin might also be relevant.
Does anyone know if that described motor/clutch arrangement has been carried on through the NG/MAX line?
Would an engineer care to comment on how a duel between the two systems might play out?
PS. The bulletin tends to support one trim wheel rotation = 0.1 units of trim (... the stabilizer trim wheel coasted up to 40 turns (four units of trim).)
Flight Crew Operations Manual Bulletin
Number: FLR-6(FR)
Issue Date: August 10, 2012
Subject: Runaway Stabilizer Procedure
Reason: This bulletin is issued to operators of an intermittent stabilizer trim system anomaly and provide additional guidance when accomplishing the Runaway Stabilizer procedure.
Background Information
Four operators have reported instances of excessive stabilizer trim system coasting (stabilizer trim wheel continues to rotate) after the control wheel stabilizer trim switches have been activated and released. The reports indicate that when the pilot released the trim switches, the stabilizer trim wheel coasted up to 40 turns (four units of trim). In some instances the trim wheel stopped moving in the commanded direction and then rotated up to 40 turns in the opposite direction.
The stabilizer trim main electric motor turns in only one direction. It drives the stabilizer trim actuator through two electro-magnetic clutches. One clutch is engaged for nose-up trim and the other is engaged for nose-down trim. Boeing examination of a suspect clutch showed that the reported coasting and/or reverse coasting of the stabilizer manual trim wheel was due to intermittent jamming of a clutch disc in one of the clutch assemblies. As a result, the electric motor will remain mechanically connected to the stabilizer trim mechanical actuator gear system after the control wheel stabilizer trim switches have been released.
With flaps down, the electric motor can continue to rotate up to 40 additional turns of the manual trim wheel after electrical power has been removed. With flaps up, manual trim wheel coasting is not significant because of the reduced trim motor speed. The autopilot trim system, which uses a motor that turns in either direction and drives the stabilizer trim through a single clutch, does not exhibit this problem.
Boeing Service Bulletin 737-27A1191, dated October 13, 1994, and revision dated November 3, 1994, provide instructions to replace the stabilizer trim electric actuator on the stabilizer trim control system.
Recommended Operating Procedures
The current Runaway Stabilizer procedure will effectively inhibit and limit an out of trim condition. Normal pilot reaction to a runaway stabilizer of opposing the runaway with main electric trim in addition to control column force will initially resolve a runaway. The Runaway Stabilizer Checklist recall action, “STABILIZER TRIM CUTOUT SWITCHES...CUTOUT” will isolate the malfunction if the runaway was caused by the main electric trim or autopilot trim systems. The stabilizer trim cutout switches only remove electrical power to the electric motors.
If the trim wheel continues to rotate after this action has been taken, the recall action “STBILIZER TRIM WHEEL....GRASP AND HOLD” will prevent further runaway or coasting. If the electric motor remains mechanically connected to the stabilizer trim mechanical actuator gear system because of a clutch malfunction, actuating the stabilizer trim cutout switches to cutout will not immediately stop the trim wheel rotation. Grasping the trim wheel will stop the rotation more quickly than allowing the trim wheel to coast to a stop, keeping the airplane more in trim.
In accordance with the procedure, trim the stabilizer manually for the remainder of the flight.
Number: FLR-6(FR)
Issue Date: August 10, 2012
Subject: Runaway Stabilizer Procedure
Reason: This bulletin is issued to operators of an intermittent stabilizer trim system anomaly and provide additional guidance when accomplishing the Runaway Stabilizer procedure.
Background Information
Four operators have reported instances of excessive stabilizer trim system coasting (stabilizer trim wheel continues to rotate) after the control wheel stabilizer trim switches have been activated and released. The reports indicate that when the pilot released the trim switches, the stabilizer trim wheel coasted up to 40 turns (four units of trim). In some instances the trim wheel stopped moving in the commanded direction and then rotated up to 40 turns in the opposite direction.
The stabilizer trim main electric motor turns in only one direction. It drives the stabilizer trim actuator through two electro-magnetic clutches. One clutch is engaged for nose-up trim and the other is engaged for nose-down trim. Boeing examination of a suspect clutch showed that the reported coasting and/or reverse coasting of the stabilizer manual trim wheel was due to intermittent jamming of a clutch disc in one of the clutch assemblies. As a result, the electric motor will remain mechanically connected to the stabilizer trim mechanical actuator gear system after the control wheel stabilizer trim switches have been released.
With flaps down, the electric motor can continue to rotate up to 40 additional turns of the manual trim wheel after electrical power has been removed. With flaps up, manual trim wheel coasting is not significant because of the reduced trim motor speed. The autopilot trim system, which uses a motor that turns in either direction and drives the stabilizer trim through a single clutch, does not exhibit this problem.
Boeing Service Bulletin 737-27A1191, dated October 13, 1994, and revision dated November 3, 1994, provide instructions to replace the stabilizer trim electric actuator on the stabilizer trim control system.
Recommended Operating Procedures
The current Runaway Stabilizer procedure will effectively inhibit and limit an out of trim condition. Normal pilot reaction to a runaway stabilizer of opposing the runaway with main electric trim in addition to control column force will initially resolve a runaway. The Runaway Stabilizer Checklist recall action, “STABILIZER TRIM CUTOUT SWITCHES...CUTOUT” will isolate the malfunction if the runaway was caused by the main electric trim or autopilot trim systems. The stabilizer trim cutout switches only remove electrical power to the electric motors.
If the trim wheel continues to rotate after this action has been taken, the recall action “STBILIZER TRIM WHEEL....GRASP AND HOLD” will prevent further runaway or coasting. If the electric motor remains mechanically connected to the stabilizer trim mechanical actuator gear system because of a clutch malfunction, actuating the stabilizer trim cutout switches to cutout will not immediately stop the trim wheel rotation. Grasping the trim wheel will stop the rotation more quickly than allowing the trim wheel to coast to a stop, keeping the airplane more in trim.
In accordance with the procedure, trim the stabilizer manually for the remainder of the flight.
does that leave us with a severe nose down and loss of altitude in seconds as they continued trying to trim?
Not like the Asian carriers A300 crashes but more like the Asian carrier B747 dive
Did they see (perceive) different symptoms than the previous sector's crew?
Did they diagnose the problem the same way?
Was this malfunction subtly different?
@CONSO: how can they afford not to?
From a CRM perspective, I'll make a case to you: one of them (whomever at that point is non flying, so left seat?) cranking on the manual trim wheel with great vigor would reduce the load to where one pilot can handle it. That trim wheel will move the control surface to relive "yoke forces" ... but as I've not flown that aircraft, I'll accept that this case may have holes in it. (Lack of CVR information also makes me wonder what else was going on in their crew coordination effort) And that's all good to consider ... unless ... the one who cranks the trim wheel (for an unknown reason) accidentally rotates it in the wrong direction. That would make things worse.
I make no assertion that this happened.
I only mention that outside chance because, under stress, sometimes people do stuff that you (and they) would not expect. (And from running aircrews through sim training some years ago, as you task load a crew more and more you get some oddball results some times ....)
That thought leads me back to .... pilot training.
Company issue: lion air.
Training materials issue: OEM, among others, differences courses, etc.
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As someone who has followed this thread since the beginning, I do find it odd how some people are blaming the pilots for their actions when the discussions here BEFORE BOEING REVEALED THE EXISTENCE AND ACTIONS OF MCAS were so very different to those discussions much more recently.
People are "forgetting" the lack of knowledge, training and simulator knowledge of the system.
.
As someone who has followed this thread since the beginning, I do find it odd how some people are blaming the pilots for their actions when the discussions here BEFORE BOEING REVEALED THE EXISTENCE AND ACTIONS OF MCAS were so very different to those discussions much more recently.
People are "forgetting" the lack of knowledge, training and simulator knowledge of the system.
.
MickG0105, re
This is a larger question concerning complex systems and their interactions in which there may be conflicting commands depending upon sensor input, (here, 'wrong' sensor data). Things are getting much more complex as computer systems invite a digital world to make use of data in ways that are not possible with mechanical systems. Determining all possible such conflicts (or software bugs) is no longer a realistic target but eliminating, or building a resilient system, (alternative solutions, back-ups, dual-dual systems, etc.), is a realistic target.
Examining this is a design and engineering responsibility, here, of Boeing's. This is apparently a system which relies upon one sensor (out of two or three), and so is potentially a single-point-of -failure. Such a system can be described as "brittle" rather than "resilient". So a question would be, was the testing for all possible failure modes done and if so, what were the results? They will be documented somewhere and so finding out is just a matter of time.
Understand the opinion that not every snag requires a test flight. That is entirely realistic and is normal for the industry. What can be argued is the need for a test flight when primary flight controls are involved along with a continuous stick-shaker and the caution messages that were experienced on the previous three flights, and this goes to communication when writing up snags, (as has already been observed here).
PJ2
" I'm assuming that MCAS commands the AP motor. I'm not an engineer but that arrangement would seem to create the potential for an interesting battle between one motor driving through a single clutch and the other motor driving through the repeated engagement of an electro-magnetic clutch. "
Examining this is a design and engineering responsibility, here, of Boeing's. This is apparently a system which relies upon one sensor (out of two or three), and so is potentially a single-point-of -failure. Such a system can be described as "brittle" rather than "resilient". So a question would be, was the testing for all possible failure modes done and if so, what were the results? They will be documented somewhere and so finding out is just a matter of time.
Understand the opinion that not every snag requires a test flight. That is entirely realistic and is normal for the industry. What can be argued is the need for a test flight when primary flight controls are involved along with a continuous stick-shaker and the caution messages that were experienced on the previous three flights, and this goes to communication when writing up snags, (as has already been observed here).
PJ2
Last edited by PJ2; 29th Nov 2018 at 19:01. Reason: to add, "all possible", to the sentence on conflicts
Understand the opinion that not every snag requires a test flight. That is entirely realistic and is normal for the industry. What can be argued is the need for a test flight when primary flight controls are involved along with a continuous stick-shaker and the caution messages that were experienced on the previous three flights, and this goes to communication when writing up snags, (as has already been observed here). PJ2
That's an angle of inquiry well worth pursuing.
Had the company maintenance team a gap in their tech manuals?
.
As someone who has followed this thread since the beginning, I do find it odd how some people are blaming the pilots for their actions when the discussions here BEFORE BOEING REVEALED THE EXISTENCE AND ACTIONS OF MCAS were so very different to those discussions much more recently.
People are "forgetting" the lack of knowledge, training and simulator knowledge of the system.
.
As someone who has followed this thread since the beginning, I do find it odd how some people are blaming the pilots for their actions when the discussions here BEFORE BOEING REVEALED THE EXISTENCE AND ACTIONS OF MCAS were so very different to those discussions much more recently.
People are "forgetting" the lack of knowledge, training and simulator knowledge of the system.
.
And the crew of previous flight also recognized there was a trim problem, but in their case almost immediately disabled the automated trim and trimmed via the mechanical trim wheels.
- GY
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The pilots on lion 610 were in regular contact with ATC and as late as 20 seconds before impact with the ocean they indicated their preferred flight level. This suggests they were not under duress in operating the aircraft until the very end. It is still very much unclear why their successful and consistent NU trim corrections are suddenly insufficient to counteract MCAS.
So the question is, why the change in which pilot was flying? CVR will go a long ways in helping figure this out if it can be found
Lonewolf_50, I believe the preliminary report includes comments regarding the thoroughness of snags. If one had an altimeter or airspeed discrepancy beyond published limits, one fixes it of course, but sometimes the only way of ensuring they are working correctly is to test them at altitude.
The stickshaker on the previous flight wasn't conveyed in the snag. The investigation needs to determine why not - what "hat" was being worn when that piece of information was not provided?
The stickshaker on the previous flight wasn't conveyed in the snag. The investigation needs to determine why not - what "hat" was being worn when that piece of information was not provided?