MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures
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I believe the information released on GT610 indicated that the captain was using his thumb switch (yoke) to counter MCAS but that the FO did not countinue with it as aggressively ?
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as a slight tangent, I wonder if the various authorities looking into the human factors of pilots interacting with ever more complex aircraft systems will also look at maintenance. It's fairly obvious from the LT flight before the crashed one that 3 pilots had their hands full with the stick shaker and stall horn going the entire way home, and trim disabled, that then resulted in a tech log writeup of "STS running in reverse" and the crew disappeared off home for bikkies and bed leaving a tech crew to scratch their head over what the entry meant.
The system is more suited to a tail dragger without electrics than a modern airliner with systems up the wazoo and intense 24/7 flying schedules and hundreds of passengers.
If I was recertifying the 737 I would at least insist on a EICAS type system that maintenance could access. We've agreed pilots can't be expected to be expert in all the underlying complexities of the aircraft engineering systems, yet we expect them to be able to write a spot on entry in the tech log. HF101 fail in my book, Add in low hour newbie pilots and it's an epic HF101 fail.
The system is more suited to a tail dragger without electrics than a modern airliner with systems up the wazoo and intense 24/7 flying schedules and hundreds of passengers.
If I was recertifying the 737 I would at least insist on a EICAS type system that maintenance could access. We've agreed pilots can't be expected to be expert in all the underlying complexities of the aircraft engineering systems, yet we expect them to be able to write a spot on entry in the tech log. HF101 fail in my book, Add in low hour newbie pilots and it's an epic HF101 fail.
Last edited by tiddles52; 14th Oct 2019 at 13:54.
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as a slight tangent, I wonder if the various authorities looking into the human factors of pilots interacting with ever more complex aircraft systems will also look at maintenance. It's fairly obvious from the ET flight before the crashed one that 3 pilots had their hands full with the stick shaker and stall horn going the entire way home, and trim disabled, that then resulted in a tech log writeup of "STS running in reverse" and the crew disappeared off home for bikkies and bed leaving a tech crew to scratch their head over what the entry meant.
Similarly, it has been suggested elsewhere that the Lion Air maintenance staff was under pressure to minimize downtime on the fleet which may have contributed to a less than thorough diagnosis and repair. IIRC, there was a history of problems with this aircraft even before the penultimate flight. I imagine these possibilities will be looked at by the official accident team.
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I see a pattern in B737 MAX threads, we have lots of interesting posts by gums, Takwis, et al, those posts which question the design choices made by Boeing, are conveniently ignored and left unanswered by the PR machine, perhaps because they have no solid arguments to counter them, then the conversation is conveniently steered to pilot error, lack of airmanship, lack of maintenance, bad airline reputation, energy rays, AF447, you name it.
All this in an attempt to deviate attention from MCAS and the flawed certification process for the B737 MAX.
A few months ago FCeng84 did provide valuable information about the MAX then he disappeared, then came 737driver with an heroic defense of the Boeing Company, and now we get external articles "crafted" in such a way as to make the dead pilots look incompetent.
Boeing & the FAA should concentrate on fixing the B737 MAX design for good, not just a software hack to mitigate the MCAS debacle, it seems EASA is the only player still exerting some sort of pressure to actually improve the safety of the MAX.
A proper fix may require lots of time, money, and a new certification process, the alternative is accepting a greater risk for loss of human lives.
All this in an attempt to deviate attention from MCAS and the flawed certification process for the B737 MAX.
A few months ago FCeng84 did provide valuable information about the MAX then he disappeared, then came 737driver with an heroic defense of the Boeing Company, and now we get external articles "crafted" in such a way as to make the dead pilots look incompetent.
Boeing & the FAA should concentrate on fixing the B737 MAX design for good, not just a software hack to mitigate the MCAS debacle, it seems EASA is the only player still exerting some sort of pressure to actually improve the safety of the MAX.
A proper fix may require lots of time, money, and a new certification process, the alternative is accepting a greater risk for loss of human lives.
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Recommendation R3.4: The FAA should review the natural (bare airframe) stalling characteristics of the B737 MAX to determine if unsafe characteristics exist. If unsafe characteristics exist, the design of the speed trim system (STS)/MCAS/elevator feel shift (EFS) should be reviewed for acceptability
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EASA appears to have been among the first authorities to insist upon good answers to hard questions, but both the preliminary report from NTSB and the JATR report, the other day, seem to indicate that others are on the same path. This, from JATR, for instance, is serious stuff:
Recommendation R3.4: The FAA should review the natural (bare airframe) stalling characteristics of the B737 MAX to determine if unsafe characteristics exist. If unsafe characteristics exist, the design of the speed trim system (STS)/MCAS/elevator feel shift (EFS) should be reviewed for acceptability
That would be a very good start to bring some transparency and understanding of the context in which decisions were made.
I see a pattern in B737 MAX threads, we have lots of interesting posts by gums, Takwis, et al, those posts which question the design choices made by Boeing, are conveniently ignored and left unanswered by the PR machine, perhaps because they have no solid arguments to counter them, then the conversation is conveniently steered to pilot error, lack of airmanship, lack of maintenance, bad airline reputation, energy rays, AF447, you name it.
All this in an attempt to deviate attention from MCAS and the flawed certification process for the B737 MAX.
A few months ago FCeng84 did provide valuable information about the MAX then he disappeared, then came 737driver with an heroic defense of the Boeing Company, and now we get external articles "crafted" in such a way as to make the dead pilots look incompetent.
Boeing & the FAA should concentrate on fixing the B737 MAX design for good, not just a software hack to mitigate the MCAS debacle, it seems EASA is the only player still exerting some sort of pressure to actually improve the safety of the MAX.
A proper fix may require lots of time, money, and a new certification process, the alternative is accepting a greater risk for loss of human lives.
All this in an attempt to deviate attention from MCAS and the flawed certification process for the B737 MAX.
A few months ago FCeng84 did provide valuable information about the MAX then he disappeared, then came 737driver with an heroic defense of the Boeing Company, and now we get external articles "crafted" in such a way as to make the dead pilots look incompetent.
Boeing & the FAA should concentrate on fixing the B737 MAX design for good, not just a software hack to mitigate the MCAS debacle, it seems EASA is the only player still exerting some sort of pressure to actually improve the safety of the MAX.
A proper fix may require lots of time, money, and a new certification process, the alternative is accepting a greater risk for loss of human lives.
"Truth is ever to be found in simplicity, and not in the multiplicity and confusion of things" Sir Isaac Newton
Oct 2018, splash 1st Max
Preliminary investigation,
Public acknowledgement of a new hitherto unknown (to flight crew) system incorporated.
response: follow a procedure without crew training
March 2019 plant 2nd Max.
aircraft grounded by NAA's around the world. Trump does his bit belatedly requiring the FAA to follow the overseas grounding.
Repurposing of the MCAS system disclosed.
Oct 15 2019, Max variant remains grounded...
If the problem was the crews, then training them would have resulted in RTS in short order, following intervention training. It has not. The foreign NAA's remain critical of the lapses in certification that has been revealed to date. That is not a pilot matter, that is a manufacturer design, certification and oversight issue.
As Feynman said post Challenger, "...for nature cannot be fooled"
Boeing and the FAA have reluctantly accepted that something somehow needs to be done with respect to a potentially deadly MAX quirk. Most of everybody’s effort these months goes into remedying that.
Boeing and the FAA appear to keep quiet as to some other certification aspect that has been successfully swept under the rug when the NG was created, or let’s say, developed.
The two MAX accidents however now have pulled the whole rug away.
The use of the manual trim wheel to tame the beast when some hardware failure opened its cage was never a particular practical solution, but in the present time it has become even more out of place than 50 years ago. Also, the trim wheels have been made even smaller when the NG came about. The NG, that notably introduced a larger wing and an increased span stabilizer.
No crashes have put this silently accepted anomaly on the table. On the contrary, the NG has an admirable safety record. But it still cheated by pointing out it’s grandfather rights rather than adhering to state-of-the-art standards. Now the question is whose signatures will appear under the conclusion that the exemplary safety record allows waiving this uncovered certification hole, as well as which other authorities will be willing to agree? This would be unbelievably unprecedented.
On top of that, if two pilots can in some conditions already have problems with the manual trim wheel as a last resort, what about the situation when one of them is out of the cockpit on a personal needs break? A suddenly rogue airplane is supposed to remain controllable by the temporary cruise minimum of one pilot. Because, logically, during cruise a single pilot shall be able to initially tame the beast. It is my understanding that both the grounded MAX and the 5000 still operational NGs fail to satisfy this criterion.
And it’s not a software thing.
Boeing and the FAA appear to keep quiet as to some other certification aspect that has been successfully swept under the rug when the NG was created, or let’s say, developed.
The two MAX accidents however now have pulled the whole rug away.
The use of the manual trim wheel to tame the beast when some hardware failure opened its cage was never a particular practical solution, but in the present time it has become even more out of place than 50 years ago. Also, the trim wheels have been made even smaller when the NG came about. The NG, that notably introduced a larger wing and an increased span stabilizer.
No crashes have put this silently accepted anomaly on the table. On the contrary, the NG has an admirable safety record. But it still cheated by pointing out it’s grandfather rights rather than adhering to state-of-the-art standards. Now the question is whose signatures will appear under the conclusion that the exemplary safety record allows waiving this uncovered certification hole, as well as which other authorities will be willing to agree? This would be unbelievably unprecedented.
On top of that, if two pilots can in some conditions already have problems with the manual trim wheel as a last resort, what about the situation when one of them is out of the cockpit on a personal needs break? A suddenly rogue airplane is supposed to remain controllable by the temporary cruise minimum of one pilot. Because, logically, during cruise a single pilot shall be able to initially tame the beast. It is my understanding that both the grounded MAX and the 5000 still operational NGs fail to satisfy this criterion.
And it’s not a software thing.
Last edited by Plumb Bob; 15th Oct 2019 at 04:32. Reason: Layout is difficult to manage.
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The certification process of the 737 MAX seems very much the same as the 777X, over the same period, same FAA, same Boeing and same Congress rulemaking, FAA reauthorizations and certification process streamlining.
US Congress, GAO are very satisfied their demands on aircraft certification streamlining were implemented in the 2011-2017 period. They do the rulemaking, FAA budgets. Only more delegation of certification should be done by FAA and the EASA should avoid doing their own checks. FAA should work on that.. https://www.gao.gov/assets/690/683649.pdf
Grandfathering design and requirements were taken to a new level for the all new 777X & DOA’s are all over the place, certifying huge “minor” design changes with limited FAA oversight, special conditions and 27 yr old requirements.
Nobody wants to be the messenger, fearing to hurt the company it’s (nice) employees and the great looking 777X. If Boeing is serious they’ll let JATR do a review of 777X certification. Shouldn’t take very long, I think they can do a lot of copy-paste..
Last edited by keesje; 15th Oct 2019 at 07:59.
MCAS is designed to increase stick force at parts of the flight envelope where, by implication, aerodynamic forces no longer present to the flight crew as they do in 'normal' flight. Moreover, during the design and development phase Boeing engineers found that this effect was far more marked than the original implementation of MCAS was able to counter.
This raises the questions of
1. How big is this corner of the envelope on this airframe with these engines
2. How much more hazardous is this corner of the envelope pn the MAX than on, say, the NG
3. What information and training (if any) should be provided to flight crew to avoid getting into this position
4. What actions or training, if any, in addition to existing checklists and/or procedures are necessary to recover to normal flight in the event of MCAS failing OFF
And the reason I say it is related to the above question is because I suppose that the yoyo method of unloading aero loads presupposes that MCAS is turned off AND that the plane will deliberately be flown into what I take to be the conditions for which MCAS is designed to be a risk control.
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Not sure if this has been previously covered, but China Southern's B737 MAX 8, B-1205, seems to have been doing quite a bit of flying over the last month. Does anyone know if these are evaluation flights?
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FR24 shows flight numbers and schedules that look like revenue flights. Confusing.
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The simplest way to explain it is that the harder one has to push or pull on the control column, the harder it will be to use the manual trim wheel. Thus larger elevator deflections, higher speeds, and (I believe) lower altitudes will increase the dynamic pressure on the elevator which then places more pressure on the jackscrew mechanisms. That said, if the stab is kept reasonably close to a neutral trim state, there is little problem in using the manual trim wheel throughout the flight envelope.
Salute!
Well, Tom, Hans and Byros...... The mods shut off the Tech Log threads very early for some reason, and they had very good tech data, discussions and diagrams and such. Not a lotta politics, conspiracy theories and such. Some human factors, but that is normal when looking at an accident from a perspective involving personal close calls or actual crashes one survived. Beats the hell outta me why we can not talk technical, even get into the FAR certification stuff and let the polotics over here on the basic "rumor" forum.
Before retiring back to the cave, I would love to take a poll of all the 737 drivers here, and they seem outnumbered by the wannabes and others....
Question: Hiow nuch did you know about MCAS in the summer of 2018 after flying a few legs in the MAX?
Gums asks....
Well, Tom, Hans and Byros...... The mods shut off the Tech Log threads very early for some reason, and they had very good tech data, discussions and diagrams and such. Not a lotta politics, conspiracy theories and such. Some human factors, but that is normal when looking at an accident from a perspective involving personal close calls or actual crashes one survived. Beats the hell outta me why we can not talk technical, even get into the FAR certification stuff and let the polotics over here on the basic "rumor" forum.
Before retiring back to the cave, I would love to take a poll of all the 737 drivers here, and they seem outnumbered by the wannabes and others....
Question: Hiow nuch did you know about MCAS in the summer of 2018 after flying a few legs in the MAX?
Gums asks....
Last edited by gums; 15th Oct 2019 at 18:37. Reason: typo
The simplest way to explain it is that the harder one has to push or pull on the control column, the harder it will be to use the manual trim wheel. Thus larger elevator deflections, higher speeds, and (I believe) lower altitudes will increase the dynamic pressure on the elevator which then places more pressure on the jackscrew mechanisms. That said, if the stab is kept reasonably close to a neutral trim state, there is little problem in using the manual trim wheel throughout the flight envelope.
Salute!
Well, Tom, Hans and Byros...... The mods shut off the Tech Log threads very early for some reason, and they had very good tech data, discussions and diagrams and such. Not a lotta politics, conspiracy theories and such. Some human factors, but that is normal when looking at an accident from a perspective involving personal close calls or actual crashes one survived. Beats the hell outta me why we can not talk technical, even get into the FAR certification stuff and let the polotics over here on the basic "rumor" forum.
Before retiring back to the cave, I would love to take a poll of all the 737 drivers here, and they seem outnumbered by the wannabes and others....
Question: Hiow nuch did you know about MCAS in the summer of 2018 after flying a few legs in the MAX?
Gums asks....
Well, Tom, Hans and Byros...... The mods shut off the Tech Log threads very early for some reason, and they had very good tech data, discussions and diagrams and such. Not a lotta politics, conspiracy theories and such. Some human factors, but that is normal when looking at an accident from a perspective involving personal close calls or actual crashes one survived. Beats the hell outta me why we can not talk technical, even get into the FAR certification stuff and let the polotics over here on the basic "rumor" forum.
Before retiring back to the cave, I would love to take a poll of all the 737 drivers here, and they seem outnumbered by the wannabes and others....
Question: Hiow nuch did you know about MCAS in the summer of 2018 after flying a few legs in the MAX?
Gums asks....
Nothing!
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Yes, I wasn't clear enough, I recall there was mention in the now closed threads, that once you got to full AND or ANU trim, there might be areas, even inside the normal W/B, Altitude and IAS envelope where it would be impossible to get back to in-trim without maneuvers like the yo-yo. I was trying to remember if this only applied to manual trim, or also to thumb switch trim, and what the speeds/altitudes where, where this became an issue.
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Grandfathering design and requirements were taken to a new level for the all new 777X & DOA’s are all over the place, certifying huge “minor” design changes with limited FAA oversight, special conditions and 27 yr old requirements.
Nobody wants to be the messenger, fearing to hurt the company it’s (nice) employees and the great looking 777X. If Boeing is serious they’ll let JATR do a review of 777X certification. Shouldn’t take very long, I think they can do a lot of copy-paste..
Nobody wants to be the messenger, fearing to hurt the company it’s (nice) employees and the great looking 777X. If Boeing is serious they’ll let JATR do a review of 777X certification. Shouldn’t take very long, I think they can do a lot of copy-paste..
The manufacturers cannot keep building aircraft in flight...
Getting back on discussion...
all of this topic on stab trim/MCAS...this was never meant to be a system to control stall, or be very active to control the ac.
Set the green band on TO and let the AP stab balance flight with altitude and decreasing fuel weight.
It was a nice convenience....
Look what it turned into...,
On a side note, there is a news entity reported that the Boeing "NMA" is proposed to be a 767-400 metal fuselage with composite wings, and large engines with a lift kit on the landing gear....
Enter the 767X
https://simpleflying.com/boeing-767x-nma/
lesson NOT learned..
Last edited by Smythe; 16th Oct 2019 at 00:52.
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Plot thickens- phony documents ???
By Alan Levin
and Harry Suhartono
Bloomberg News
Weeks after a Lion Air jet crashed in the Java Sea, killing all 189 aboard, an airline employee gave investigators photographs meant to show that a crucial repair had been properly performed the day before the disaster.
Yet the photos may not show what was claimed.
The time displayed in photos of a computer screen in the cockpit of the Boeing 737 MAX indicated they actually had been taken before the repair was performed, according to a draft of the final crash report being prepared by Indonesia’s National Transportation Safety Committee (NTSC), portions of which were reviewed by Bloomberg News.
Investigators were similarly unable to confirm the authenticity of other photos in the packet, which were supposed to show how a piece of equipment near the jet’s nose had been calibrated, according to the report. There were indications that the pictures depicted a different plane, according to two people familiar with the investigation.
The draft report doesn’t say whether anyone falsified or misrepresented the photos — which would be considered a serious breach of protocol — but concludes that they may not be valid evidence.
The incident injected additional tension into the already fraught international investigation in which billions of dollars and the reputations of airlines, manufacturers and entire nations are on the line.
737 MAX CRISIS COMPLETE COVERAGE
Dennis Muilenburg out as Boeing chairman but keeps CEO position
Boeing rejected 737 MAX safety upgrades before fatal crashes, whistleblower says
Extra pilot saved doomed Lion Air jetliner on next-to-last flight
More
According to one person briefed on the matter, the Indonesia-based airline has told investigators that the allegations about the photos are unsubstantiated and shouldn’t be mentioned in the final report of the October 2018 crash. But to others involved in one of the most significant accident probes in decades, it could represent an attempt to mislead investigators about a critical aspect of the case and needs to be documented, said two other people who were briefed about the existence of the photos.
Lion Air spokesman Danang Prihantoro said that he could not comment on the investigation. Representatives of the U.S. Federal Aviation Administration, Boeing and National Transportation Safety Board (NTSB) declined to comment on the existence of the photos.
Indonesia’s NTSC, which is overseeing the investigation, is finalizing the report and expects to release it by early November. Anggo Anurogo, a spokesman for the investigation agency, said it wouldn’t comment on the report before its release.
Portions of the draft reviewed by Bloomberg News say an engineer gave the photos to investigators to show that the replacement of a sensor on the plane on Oct. 28 had been done properly. The sensor, known as an “angle-of-attack” vane, was malfunctioning on the very next flight as well as the one the next day that crashed and is at the heart of the investigation, according to an NTSC preliminary report released last November.
Some of the images were taken of the inside of an equipment compartment where the faulty sensor was attached, according to the people familiar with the investigation. Part of the calibration process occurs in that location.
Visible in the background of these photos was other equipment with identification marks, the people said. Officials at Boeing were able to trace at least one of the devices to a different 737 MAX jet operated by Lion Air, they said.
Other photos were shot in a 737 MAX cockpit, where mechanics check to see that the sensor is providing accurate readings, the people said. Those photos showed the captain’s flight display, but the time shown on its digital clock was before the repair being performed, according to the draft report.
Lion Air, which already was pushing back on preliminary conclusions by investigators, has challenged assertions that the photos were falsified and asked the NTSC not to include the pictures and any reference to them in its final report, according to one person familiar with the airline’s view of the matter.
The airline further said the photos didn’t come from the carrier, the person said. The pictures were blurry, and the airline couldn’t understand how equipment markings could have been identified, the person said.
Investigative reports of crashes often contain hundreds of pages and document evidence collected and significant issues faced during the probe.
The repair depicted by the photos is central to the investigation. A malfunction of the angle-of-attack sensor is believed to have triggered an automated system on the plane to repeatedly force its nose down, eventually causing the pilots to lose control and crash at high speed into the ocean.
Documents reviewed by Bloomberg News show the repair station XTRA Aerospace in Miramar, Florida, had worked on the sensor. It was installed on the Lion Air plane on Oct. 28 in Denpasar, Indonesia, after pilots on earlier flights had reported problems with instruments displaying speed and altitude. XTRA has said it is cooperating with the investigation.
For months, examinations of the Lion Air crash and the second, similar accident March 10 of a 737 MAX operated by Ethiopian Airlines have focused on the angle-of-attack sensors and their role in the functioning of a feature built into the jet known as Maneuvering Characteristics Augmentation System.
MCAS, designed to keep the nose of the plane from drifting too far up in flight, was fed data from one of the plane’s two angle-of-attack sensors, devices that protrude from the jet’s nose and resemble a weather vane.
When it senses the nose has risen too far, it automatically pushes it back down, reducing the risk of an aerodynamic stall. Investigators believe a malfunction of the sensor on board the Lion Air flight mistakenly forced the nose of the plane down repeatedly until the pilots lost control.
The same failure occurred Oct. 28 immediately after the repair on the Lion Air jet, but pilots on that flight were able to recover and fly to their destination. Not so on the final flight of the jet, when the pilots began fighting for control shortly after takeoff.
The plane hit the water in a high-speed dive, shattering into pieces. While investigators haven’t said whether they’ve recovered the angle-of-attack sensor from the bottom of the sea, the plane’s black-box flight recorder was brought up and confirmed the sensor was malfunctioning.
The crash, and the Ethiopian Airlines disaster months later, prompted a worldwide grounding of Boeing’s best-selling jet, leading to billions of dollars in losses and international investigations into how the system was designed and approved.
The mechanic who worked on the Lion Air jet before the crash reported the new device was installed according to the maintenance procedure, the November 2018 preliminary report said.
“Installation test and heater system test result good,” said an entry in the plane’s maintenance log included in the report. The mechanic also told a pilot about to fly the plane that the sensor “had been tested accordingly,” the report said.
However, data in the report suggest the calibration wasn’t done properly or at all, said John Goglia, a former airline mechanic who used to serve on the NTSB.
Such processes are routine and relatively simple, Goglia said. The procedure is designed as a fail-safe to ensure that a mechanic can quickly determine whether a newly installed sensor isn’t working.
“They were given an unairworthy airplane because the maintenance was incomplete and didn’t correct the problem,” he said.
Alan Levin
Harry Suhartono
and Harry Suhartono
Bloomberg News
Weeks after a Lion Air jet crashed in the Java Sea, killing all 189 aboard, an airline employee gave investigators photographs meant to show that a crucial repair had been properly performed the day before the disaster.
Yet the photos may not show what was claimed.
The time displayed in photos of a computer screen in the cockpit of the Boeing 737 MAX indicated they actually had been taken before the repair was performed, according to a draft of the final crash report being prepared by Indonesia’s National Transportation Safety Committee (NTSC), portions of which were reviewed by Bloomberg News.
Investigators were similarly unable to confirm the authenticity of other photos in the packet, which were supposed to show how a piece of equipment near the jet’s nose had been calibrated, according to the report. There were indications that the pictures depicted a different plane, according to two people familiar with the investigation.
The draft report doesn’t say whether anyone falsified or misrepresented the photos — which would be considered a serious breach of protocol — but concludes that they may not be valid evidence.
The incident injected additional tension into the already fraught international investigation in which billions of dollars and the reputations of airlines, manufacturers and entire nations are on the line.
737 MAX CRISIS COMPLETE COVERAGE
Dennis Muilenburg out as Boeing chairman but keeps CEO position
Boeing rejected 737 MAX safety upgrades before fatal crashes, whistleblower says
Extra pilot saved doomed Lion Air jetliner on next-to-last flight
More
According to one person briefed on the matter, the Indonesia-based airline has told investigators that the allegations about the photos are unsubstantiated and shouldn’t be mentioned in the final report of the October 2018 crash. But to others involved in one of the most significant accident probes in decades, it could represent an attempt to mislead investigators about a critical aspect of the case and needs to be documented, said two other people who were briefed about the existence of the photos.
Lion Air spokesman Danang Prihantoro said that he could not comment on the investigation. Representatives of the U.S. Federal Aviation Administration, Boeing and National Transportation Safety Board (NTSB) declined to comment on the existence of the photos.
Indonesia’s NTSC, which is overseeing the investigation, is finalizing the report and expects to release it by early November. Anggo Anurogo, a spokesman for the investigation agency, said it wouldn’t comment on the report before its release.
Portions of the draft reviewed by Bloomberg News say an engineer gave the photos to investigators to show that the replacement of a sensor on the plane on Oct. 28 had been done properly. The sensor, known as an “angle-of-attack” vane, was malfunctioning on the very next flight as well as the one the next day that crashed and is at the heart of the investigation, according to an NTSC preliminary report released last November.
Some of the images were taken of the inside of an equipment compartment where the faulty sensor was attached, according to the people familiar with the investigation. Part of the calibration process occurs in that location.
Visible in the background of these photos was other equipment with identification marks, the people said. Officials at Boeing were able to trace at least one of the devices to a different 737 MAX jet operated by Lion Air, they said.
Other photos were shot in a 737 MAX cockpit, where mechanics check to see that the sensor is providing accurate readings, the people said. Those photos showed the captain’s flight display, but the time shown on its digital clock was before the repair being performed, according to the draft report.
Lion Air, which already was pushing back on preliminary conclusions by investigators, has challenged assertions that the photos were falsified and asked the NTSC not to include the pictures and any reference to them in its final report, according to one person familiar with the airline’s view of the matter.
The airline further said the photos didn’t come from the carrier, the person said. The pictures were blurry, and the airline couldn’t understand how equipment markings could have been identified, the person said.
Investigative reports of crashes often contain hundreds of pages and document evidence collected and significant issues faced during the probe.
The repair depicted by the photos is central to the investigation. A malfunction of the angle-of-attack sensor is believed to have triggered an automated system on the plane to repeatedly force its nose down, eventually causing the pilots to lose control and crash at high speed into the ocean.
Documents reviewed by Bloomberg News show the repair station XTRA Aerospace in Miramar, Florida, had worked on the sensor. It was installed on the Lion Air plane on Oct. 28 in Denpasar, Indonesia, after pilots on earlier flights had reported problems with instruments displaying speed and altitude. XTRA has said it is cooperating with the investigation.
For months, examinations of the Lion Air crash and the second, similar accident March 10 of a 737 MAX operated by Ethiopian Airlines have focused on the angle-of-attack sensors and their role in the functioning of a feature built into the jet known as Maneuvering Characteristics Augmentation System.
MCAS, designed to keep the nose of the plane from drifting too far up in flight, was fed data from one of the plane’s two angle-of-attack sensors, devices that protrude from the jet’s nose and resemble a weather vane.
When it senses the nose has risen too far, it automatically pushes it back down, reducing the risk of an aerodynamic stall. Investigators believe a malfunction of the sensor on board the Lion Air flight mistakenly forced the nose of the plane down repeatedly until the pilots lost control.
The same failure occurred Oct. 28 immediately after the repair on the Lion Air jet, but pilots on that flight were able to recover and fly to their destination. Not so on the final flight of the jet, when the pilots began fighting for control shortly after takeoff.
The plane hit the water in a high-speed dive, shattering into pieces. While investigators haven’t said whether they’ve recovered the angle-of-attack sensor from the bottom of the sea, the plane’s black-box flight recorder was brought up and confirmed the sensor was malfunctioning.
The crash, and the Ethiopian Airlines disaster months later, prompted a worldwide grounding of Boeing’s best-selling jet, leading to billions of dollars in losses and international investigations into how the system was designed and approved.
The mechanic who worked on the Lion Air jet before the crash reported the new device was installed according to the maintenance procedure, the November 2018 preliminary report said.
“Installation test and heater system test result good,” said an entry in the plane’s maintenance log included in the report. The mechanic also told a pilot about to fly the plane that the sensor “had been tested accordingly,” the report said.
However, data in the report suggest the calibration wasn’t done properly or at all, said John Goglia, a former airline mechanic who used to serve on the NTSB.
Such processes are routine and relatively simple, Goglia said. The procedure is designed as a fail-safe to ensure that a mechanic can quickly determine whether a newly installed sensor isn’t working.
“They were given an unairworthy airplane because the maintenance was incomplete and didn’t correct the problem,” he said.
Alan Levin
Harry Suhartono