Boeing 737 MAX Crash Reveals Severe Problem With Older Boeing 737 NGs
The fleet of Boeing 737 MAX planes will stay out on the ground longer than anticipated. Boeing promised a new software package to correct the severe problems with its Maneuver Characteristics Augmentation System (MCAS). The delivery was supposed to be ready in April. A month later it has still not arrived at the Federal Aviation Agency where it will take at least a month to certify it. The FAA will not be the only one to decide when the plane can come back into the flight line. Other country's agencies will do their own independent review and will likely take their time.
The 737 MAX incident also revealed a problem with older generations of the 737 type of plane that is only now coming into light. Simulator experiments (video) showed that the recovery procedures Boeing provided for the case of a severe mistrim of the plane is not sufficient to bring the plane back under control. The root cause of that inconvenient fact does not lie with the 737 MAX but with its predecessor, the Boeing 737 Next Generation or NG.
This was known in pilot circles for some time but will only now receive wider public attention:
The Boeing 737 Max's return to commercial airline service is reportedly being further delayed by the Federal Aviation Administration.US government officials told The Wall Street Journal's Andy Pasztor that the FAA is evaluating the emergency procedures for not only the Max but also the older generations of the 737 including the [once] hot-selling Boeing 737 NG.
According to the officials, the broadened evaluation will take a look at how pilots of all 737 variant are instructed to respond to emergency situations.
Here is a detailed explanation why the FAA is now looking into the pilot training for older 737 types.
The 737 NG (-600/-700/-800/-900) was the third generation derivative of the 737 and followed the 737 Original (-100/-200) and Classic (−300/-400/-500) series. The first NG flew in 1997. Some 7,000 were build and most of them are still flying.
Two technical modifications that turned out to be a problem during the recent incidents occurred during the redesign of the 737 Classic into the New Generation series.
In the NG series a new Flight Management Computer (FMC) was added to the plane. (The FMC helps the pilots to plan and manage the flight. It includes data about airports and navigation points. It differs from the two Flight Control Computers in that it has no control over physical elements of the plane.)
The FMC on the NG version has two input/output units each with a small screen and a larger keyboard below it. They are next to the knees of the pilot and the copilot They are located on the central pedestal between the pilots right below the vertical instrument panel (see pic below). The lengthy FMCs did not fit on the original central pedestal. The trim wheels on each side, used to manually trim the airplane in its longitudinal axis or pitch, were in the way. Boeing's 'solution' to the problem was to make the manual trim wheels smaller.
737 NG cockpit with FMC panels and with smaller trim wheels (black with a white stripe)
bigger
737 Original-200 cockpit with larger trim wheels (black with a white stripe)
bigger
The smaller trim wheels require more manual force to trim with the same moment of force or torque than the larger ones did.
Another change from the 737 Classic to the 737 NG was an increase in the size of the rear horizontal flight surface, the stabilizer.
The stabilizer at the rear of the plane can be turned around a central pivot point. The natural nose up or nose down characteristics of an airplane change during a flight depending on the speed at which the airplane flies. The stabilizer can be moved during a flight by a jackscrew (vid) which is turned by either an electric motor, or via cables from the hand-cranked trim wheels in the cockpit. Trimming the airplane keeps it level at all flyable speeds.
At the rear end of the stabilizer is the elevator surface (blue arrow in the pic below). The elevator is moved by the column or yoke the pilot uses to control the plane. During a flight the pilot, or an automated stabilizer trim system (STS), will electrically trim the stabilizer so that no additional force on the column is required for the plane to stay at its flight level.
In case of a mistrim of the stabilizer, the plane puts its nose up or down and the pilot will have to push or pull his column to move the elevator to counter the mistrim of the stabilizer. Depending on the position of the stabilizer and the speed of the airplane this can require very significant force. In some cases it might be impossible.
Graphic via The Air Current and Peter Lemme - bigger
The size of the stabilizer increased from 31.40 square meter on the Classic to 32.78 sqm on the NG and MAX. Meanwhile the size of the elevator, the primary control surface the pilot can use to counter a mistrimmed stabilizer, was kept at its original size of 6.55 sqm.
It is therefore more difficult for the pilot of a 737 NG or 737 MAX plane to use the elevator to counter a mistrimmed stabilizer than it was on the earlier 737 Classic series.
In 1961 a mistrimmed stabilizer on a Boeing 707 caused the crash of an airplane. All on board died. The root cause was a malfunction in the electrical switch the pilot normally uses to electrically move the stabilizer. The switch stuck in an ON position and the motor moved the stabilizer to its most extreme position. The plane's nose went up until it aerodynamically stalled. The pilots were unable to recover from the situation.
The type of incident where an electric malfunction drives the stabilizer into an extreme position is since known as a 'runaway stabilizer'.
To get a type rating for Boeing planes the pilots have to learn a special procedure to diagnose and correct a runaway stabilizer situation. The procedure is a so called 'memory item'. The pilots must learn it by heart. The corrective action is to interrupt the electric circle that supplies the motor which drives the jackscrew and moves the stabilizer. The pilots then have to use the hand-cranked trim wheels to turn the jackscrew and to bring the stabilizer back into a normal position.
737 stabilizer jackscrew - bigger
[The MCAS incidents on the crashed 737 MAX were not of the classic runaway stabilizer type. A runaway stabilizer due to an electric malfunction is expected to move the stabilizer continuously. The computerized MCAS operated intermittently. It moved the stabilizer several times, with pauses in between, until the mistrim became obvious. The pilots would not have diagnosed it as a runaway stabilizer. Only in the end are the effects of both problems similar.]
A third change from older 737s to newer types involved the manuals and the pilot training.
If due to a runaway stabilizer event the front end of the stabilizer moves up, the nose of the airplane will move down and the plane will increase its speed. To counter that the pilot pulls on his column to move the rear end of the elevator up and to bring the plane back towards level flight. As the plane comes back to level the aerodynamic pressure on the mistrimmed stabilizer increases. Attempts to manually trim in that situation puts opposing forces on the jackscrew that holds the stabilizer in its positions. The aerodynamic forces on the stabilizer can become so big that a manual cranking of the trim wheel can no longer move the jackscrew and thereby the stabilizer.
Until the introduction of the newer 737 types Boeing's pilot manuals for the 737 included a procedure that described how to overcome the situation. It was counterintuitive. If the stabilizer put the plane in an extreme nose down position the pilot was advised to first pull the column to decrease the speed. He then had to push the column forward to lower the aerodynamic forces that blocked the jackscrew. Then the manual trim wheel could be turned a bit while the plane continued to dive and again increased its speed. The procedure had to be repeated several times: pull column to decrease speed; push column to decrease the aerodynamic force on the stabilizer and its jackscrew; trim manually; repeat. The technic was known as the rollercoaster maneuver.
Excerpt from an old 737-200 manual - via The Air Current - bigger
Recently some pilots used a 737 NG flight simulator to test the procedure. They simulated the runaway stabilizer case at a height of 10,000 feet and use the rollercoaster maneuver to recover from the mistrim. When they finally had the stabilizer back into a correct trim position they found themselves at 3,000 feet height. The maneuver would thus help only when the plane is already at a significant height above ground.
Both of the recent 737 MAX crashes happened shortly after the start. The rollercoaster maneuver would not have helped those flights. But should a runaway stabilizer incident happen on a 737 NG at its normal flight level the maneuver would probably be the only chance to recover from the situation.
The crashes of the two 737 MAX revealed a number of problems with the design of the MCAS system. Several additional issues with the plane have since become known. There may be other problems with its 737 MAX that no one yet learned of. The rather casual FAA certification of the type was clearly not justified.
But the problems described above are 737 NG problems. The 380 or so existing 737 MAX are currently grounded. But some 7,000 737 NG fly about every day. The record provides that it is a relatively safe airplane. But a runaway stabilizer is a well known electrical malfunction that could by chance happen on any of those flights.
The changes from the 737 Classic to the 737 NG make it more difficult, if not impossible, for the pilots to recover from such a situation:
- The smaller manual trim wheels on the 737 NG make it more difficult to trim a runaway stabilizer back into a regular position.
- The larger stabilizer surface makes it more difficult to counter a runaway stabilizer by using the elevator which was kept at the same size.
- 737 NG pilots no longer learn the rollercoaster maneuver that is now the only way to recover from a severe mistrim.
Simulator sessions demonstrate (video) that a runaway stabilizer incident on a 737 NG can no longer be overcome by the procedures that current Boeing manuals describe.
It is pure luck that no NG crash has yet been caused by a runaway stabilizer incident. It is quite astonishing that these issues only now become evident. The 737 NG was certified by the FAA in 1997. Why is the FAA only now looking into this?
The second 737 MAX crash revealed all these issues to a larger public. Except for MCAS the trim systems on the NG and MAX are similar. The Ethiopian Airline flight 302 did not experience a runaway stabilizer, but the multiple engagement of MCAS moved the stabilizer to a similar extreme position. The pilots cut the electricity to the stabilizer motor and tried to re-trim the plane manually by turning the trim wheels. The aerodynamic forces on the stabilizer were impossible to overcome. The pilots had not learned of the rollercoaster maneuver. (Not that it would have helped much. They were too low to the ground.) They switched the motor back on to use manual electrical trim to re-trim the aircraft. Then MCAS engaged again and put them into the ground.
All NG and MAX pilots should learn the rollercoaster maneuver, preferable during simulator training. There are probably some 50,000 pilots who are certified to fly a Boeing NG. It will be an enormous and costly effort to put all of them through additional training.
But it will be more costly, for all involved, if a 737 NG crashes and kills all on board due to a runaway stabilizer incident and a lack of pilot training to overcome it. Such an incident would probably keep the whole NG fleet on the ground.
Pilots, airlines and the public should press the FAA to mandate that additional training. The FAA must also explain why it only now found out that the problem exists.
---
Previous Moon of Alabama posts on Boeing 737 issues:
- Boeing, The FAA, And Why Two 737 MAX Planes Crashed - March 12 2019
- Flawed Safety Analysis, Failed Oversight - Why Two 737 MAX Planes Crashed - March 17 2019
- Regulators Knew Of 737 MAX Trim Problems - Certification Demanded Training That Boeing Failed To Deliver - March 29 2019
- Ethiopian Airline Crash - Boeing Advice To 737 MAX Pilots Was Flawed - April 9 2019
Additional sources with more technical details:
- Vestigal Design Issues Cloud 737 MAX Crash Investigation - Jan Ostrower, The Air Current
- Stabilizer Trim - Peter Lemme, Satcom Guru
- Trim Cutout with Severe Out-of-Trim Stabilizer can be difficult to recover - Peter Lemme, Satcom Guru
- Professional Pilots Rumors Forum and News - Various authors in a number of 737 threads, PPRuNe
Posted by b on May 25, 2019 at 21:20 UTC | Permalink
on the one hand a thorough and impressive look at the subject. on the other hand i'm getting on a 737 next week and this adds to my already profound anxiety about flying. good times.
Posted by: the pair | May 25 2019 22:18 utc | 2
Very clearly stated description of how "accidents" get engineered, baked-into, into big and complex machines and systems. Wonderful.
Raises material questions about defects in regulation of airplane safety, and how that happens (can you spell "m-o-n-e-y"?) and why (repeat spelling). Regulatory Capture? Geewhiz...yatink?
Feynman's classic report on the Challenger "accident" exposes the same sort of matter.
Feynman also tells a story about Oak Ridge in the building of the plant to separate isotopes - he knew nothing of blue-prints and they showed him reams of paper, he spotted a little rectangle with an X in side..."what happens if this opens" he said (if I recall rightly) Of course he thought it looked like a window, but in the language of blueprints it was, of course, a valve.... Turned out it was a lucky question, well, maybe not for Japan...
When you build stuff or operate it one must always ask, at every junction, what if?... This is true of driving, of motorcycles, airplanes, boats, and probably taking a bath.
Posted by: Walter | May 25 2019 22:54 utc | 3
Another excellent description of the Boeing profit cancer.
Where are the cost/benefit analysis that were done to justify the profit over safety moves of Boeing? Some people are making big bucks by putting the public more at risk for profit.
Who are they and why are they not in jail?
If corporations are people like Mitt Romney says then why is Boeing not under arrest?
If we can't arrest Boeing then why not the leadership that made the profit over safety decisions? Certainly there is a paper trail.
Boeing is now like Trump by putting a clear face on the sickness that is the West governed by the elite who own global private finance and everything else.
And this sickness is having a hissy fit because it knows it can't compete against China's mixed economy and they won't let the elite own China finance.
Public versus private finance is the war that humanity is waging even though it is presented by the West as all these spinning plates of other things.
Boeing needs to be driven into bankruptcy, just like empire is being driven, to put consequences to the cancer of profit over safety.
Posted by: psychohistorian | May 25 2019 23:13 utc | 4
When is Trump going to declare that Airbus is a threat to American national security and sanction it like Huawei?
Posted by: Ghost Ship | May 25 2019 23:24 utc | 5
Correct me if I'm wrong but hasn't every single transport-category aircraft made since the Boeing 707, including Airbus, Embraer and Bombardier, used a jackscrew to position the horizontal stabilizer?
Posted by: dh | May 25 2019 23:26 utc | 6
Ah shit. I'll have to postpone my purchase of 737s now. How on earth will I now jetset the globe?
First world problems, huh...
Posted by: dan | May 25 2019 23:42 utc | 7
Jackscrews are, in most older cars and most trucks,and most machine tools the way the controls and steering works. They are ordinary, simple, and nearly foolproof. The article does not blame the jackscrew. Sometimes corrosion and maintenance issues, and rarely, manufacturing defects, can happen...nothing like that at issue in these two failure patters.
I have seen exactly one jackscrew failure, and it still worked ok, and I have had in my hands hundreds of jackscrews torn down for analysis.
The failures at hand have to do with a dead-short between the ears associated with Big Bucks and "fictionalized capitalism" - they faked it, pencil whipped the job...as we used to say when I worked for the Army...
Posted by: Walter | May 25 2019 23:48 utc | 8
@8 Thank you Walter. I'm not an engineer...just trying to pinpoint the stabilizer problem. Faulty electronics? Overloaded trim wheels? Bad design or capitalist greed?
B explained it very well but is the problem unique to Boeing?
Posted by: dh | May 25 2019 23:54 utc | 9
Unlike the recent MCAS issues on a new aircraft I suspect runaway trim on 737 NG is a rare event most pilots only experience in the simulator (unlike in the 60’s-70’s on other models) .In over 20 years of flying (737 NG) has their ever been a crash due to runaway trim? Just asking as I don't know.
This does not mean the procedures should not be corrected and additional training done.
Posted by: Pft | May 26 2019 0:13 utc | 10
thanks b.. that is discouraging to hear... it is interesting seeing the faa's role in all of this.. it reminds me of the role of the opcw and what was, or wasn't shared in the report on douma... at some point these agencies need to be scrutinized more aggressively... the author andersons of enron keep rearing their ugly heads..
Posted by: james | May 26 2019 0:18 utc | 12
Just curious, but has any airline ever reported a runaway stabilizer on a 737NG?
Obviously no 737NG has crashed from such an event, but if there is a runaway stabilizer incident then the airline is (I assume) obliged to report it to the FAA. Is that data available to the public?
Posted by: Yeah, Right | May 26 2019 0:27 utc | 14
To b; Thank you. to Walter also thank you for most informative comments. To dh #9. No way is the problem unique to Boeing. Where was that walk way/over pass which collapsed the day after it opened killing several? The Carolina's? Georgia? How about Becktel's Big Dig? The roof tiles fell in the airport tunnel killing how many? Oops no links. Wait wait
What about the atrium walk way in???? City in the US midwest. Undersized bolts. The whole thing fell down at the opening celebration. Deflection won. Cost cutting lost. Scores died. Famous engineering maxims: Two is one and one is none. Keep it simple stupid.
I vote that all airline pilots get a raise and more vacation time.
Posted by: Miss Lacy | May 26 2019 0:30 utc | 15
Great analysis, thank you B.
Clearly then even the old 737 is unsafe below 7,000 feet and probably higher for unprepared or unsuspecting pilots, because the recovery maneuver causes at least that altitude loss, and the 737 NG is further unsafe in cases where the recovery maneuver does not work.
The problem is skimping on error handling processes, the most costly, critical, and invisible part of critical systems design. Skimping is universal where profit motive governs, and infects regulators via bribes and regulatory capture. Where disasters will result very rarely, the skimping remains invisible, the investors count their gains and donate to the parties that control regulatory agencies, and managers are promoted and retire. The value of a human life is adjusted to zero by sociopathic investors and their preferred corporate managers.
Posted by: Sam F | May 26 2019 0:51 utc | 16
So basically the post is stating that boing and the faa have a culture of overlooking safety issues - no blood no foul (until there is blood).
Boing and faa would like to point the finger at pilots, birds, weather, God... etc. Lastly faa and boing will be leaking blame directed at each other and then it will be that you cant actually punish government employees and then boing is major military contractor and strategically important - too big to fail.
Basically, they have both been shown to be unreliable. Fatal to the faa, maybe to boing, maybe to passengers.
Posted by: jared | May 26 2019 1:35 utc | 17
Unlike the recent MCAS issues on a new aircraft I suspect runaway trim on 737 NG is a rare event most pilots only experience in the simulator (unlike in the 60’s-70’s on other models) .In over 20 years of flying (737 NG) has their ever been a crash due to runaway trim? Just asking as I don't know. This d\n mean the procedures s\n\b corrected and additional training done. by: Pft @10 <= Re rime and clear ice builds, especially in low altitude (take off and approaches) where icing develops along moment arm @ local positions <= trim becomes a major frantic cockpit issue.. yeah, I know icing is never a problem in a modern life exchanged for profit aircraft..
Psychohistorian seated the hard nail into government protected corporate lumber (weed exterminator Monsanto , bomb makers everywhere and vision, hearing and heart -threatened calcium channel signal corrupting 5G energies come to mind. One drop of corporation greed = the early death for large numbers of expendable humans. but never fear the secret government is at work, protecting the corporate lords and their Oligarch owners from those of you who toil to earn a living.. what you governed humans don't know, those who govern you (the governors) intend to get Assange for telling you, because the corporation lords don't want you to know.
Never has there been a better case for independent of government, independent of corporate influence audits..
The entire flying public should be allowed to audit all of the aircraft designs, construction and management decisions and FAA activities and decisions from start to finish. The life of the passenger depends on the scope and quality of the audit.
There is a safe harbor rule in securities tell the whole truth, and nothing but the truth, if you fail that requirement you must give the money investors gave you back to the investors. ..humm!
Posted by: snake | May 26 2019 2:38 utc | 18
Thanks b, for another expose on the current flaws in the U$A's brand of Capitalism.
As snake @ 18 says;"Never has there been a better case for independent of government, independent of corporate influence audits.."
Posted by: ben | May 26 2019 2:56 utc | 19
@Ghost Ship | May 25, 2019 7:24:24 PM | 5
When is Trump going to declare that Airbus is a threat to American national security and sanction it like Huawei?
Probably after he attacks Toyota. Maybe he's starting on the Japanese company.
Toyota Motor Corp. rebuked President Donald Trump’s declaration that imported cars threaten U.S. national security, signaling contentious talks are ahead for the White House and America’s key trading partners.
Posted by: Cyril | May 26 2019 3:15 utc | 20
I don't know much about commercial aircraft but even I can see that b has way ahead of other media in reporting about the Boeing/FAA clusterf*ck. Both in terms of timely info and depth of info.
Great work b!
Posted by: Jackrabbit | May 26 2019 3:36 utc | 21
@Cyril | May 25, 2019 11:15:18 PM | 20
Probably after he attacks Toyota.
Maybe Trump has already started going after Airbus:
The United States wants to put tariffs on $11.2 billion worth of EU goods ... to offset what it says are unfair European subsidies for plane manufacturer Airbus.
How much of Boeing is vulnerable to a European retaliation? I know that the 737 Max uses LEAP-1B
Posted by: Cyril | May 26 2019 4:31 utc | 22
Dear B,
Your post is likely to end up in some pilots' own custom-made manuals for reference if Boeing doesn't amend its current manuals or FAA doesn't mandate appropriate pilot training on the Boeing 737 MAX jets. Get ready to see it reprinted on other websites and blogs!
Posted by: Jen | May 26 2019 4:33 utc | 23
Hmm... how did the "Post" button get pushed?
I meant to say...
[If Trump really goes after Airbus,] How much of Boeing is vulnerable to a European retaliation? I know that the 737 Max uses LEAP-1B engines, which are made by a joint venture between Safran (France) and General Electric (US). Anything else?
Posted by: Cyril | May 26 2019 4:35 utc | 24
@ Cyril with the great questions about potential implications of tariffs/sanctions to protect Boeing market
Tariffs and sanctions could be a temporary negotiating tactic or are a slippery slope that those in control of global private finance are willing to let Boeing and other US industry leaders have to endure as long as global private finance stays viable in the world....throwing America under the bus to save the scions of empire.
Is bringing the world economies to a halt via all these "bluffs" meant for some bigger purpose?....war by other means, perhaps?
Wait until the world gets to anguish over nations debt position as part of all the fear mongering to save private finance profit while the public takes the losses in the shorts....it is all about getting and staying ahead of the narrative train....
Posted by: psychohistorian | May 26 2019 5:39 utc | 25
Possibly off topic but...
During the 1989 Airline Pilot's Strike in Oz, Labor & Union acolyte, PM Bob Hawke, solved the problem Neo-liberally by removing negotiating principles from the table and declaring a National Emergency. This empowered the airlines to sack all the recalcitrant pilots, thus reducing them to the status of truck drivers. I don't know if this was the beginning of the War On Pilots but I did read that the Captain of the plane which landed an airliner on the Hudson River, saving all on board, was on $19,000-00 p.a. and had a second job to make ends meet.
It seemed a bit short-sighted, to me, to reduce the perceived status of a group of highly-trained, and professional, airline pilots to well below the pay-scale status of qualified tradesmen and even some skilled laborers - possibly to the point of (voiceless) irrelevance?
Posted by: Hoarsewhisperer | May 26 2019 5:41 utc | 26
Small correction, the "NG" stands for NEXT Generation, not NEW Generation.
For once, Wikipedia is correct: wiki/Boeing_737#737_Next_Generation
As a former 737-300 (="Classic") and 737-700 (= "NG") pilot, I vividly remember from during the initial simulator training how difficult it was to manually trim the 737-700.
But hey, the joke in the pilot community is that "Boeing is a law firm that also makes aeroplanes."
Boeing needs to be driven into bankruptcy, just like empire is being driven, to put consequences to the cancer of profit over safety.
Posted by: psychohistorian | May 25, 2019 7:13:08 PM | 4
Absolutely and utterly agree! Those at the top of both Boeing and FAA also need to be tried for manslaughter and jailed for life.
The FAA also needs to be sanctioned by regulatory moves in EU, Russia, China and other countries which disallow all FAA certifications until the FAA have proven that the certifications were properly carried out, and validated by non-US agencies at FAA's cost. If they don't fully comply, threaten mass grounding of US-certified aircraft. There also needs to be a wide-ranging international investigation of FAA working practicies and conflicts of interests, with mandatory full disclosure (to all non-US aviation regulators and pilots unions) of all documentation and mandatory access to witnesses, again under threat of grounding of all US-certified aircraft in case of non-compliance. (It won't happen of course! There also need to similar investigations of working practices and conflicts of interest of EU aviation authorities - also won't happen, althought there might be investigations of very limited scope. Likewise for pharmaceuticals, pesticides and environmental hazards.)
Posted by: BM | May 26 2019 7:29 utc | 28
The FMC helps the pilots to plan and manage the flight. It includes data about airports and navigation points....The lengthy FMCs did not fit on the original central pedestal. The trim wheels on each side, used to manually trim the airplane in its longitudinal axis or pitch, were in the way. Boeing's 'solution' to the problem was to make the manual trim wheels smaller.
In addition to the usual greed, we see how technocratic-engineering culture is at work here: A basically worthless "hi-tech" toy (the FMC) is considered far more important than an actual safety mechanism which is manual and therefore stupid from the technocratic POV. Indeed, from this culture's POV it's an absolute value to decrease human agency and action and increase computer agency, without regard to any kind of practicality, let alone something so mundane and boring as the safety of human beings.
By the way, it's NEXT Generation, not NEW Generation.
[Thank you. I have corrected my mistake. - b.]
Posted by: 744748 | May 26 2019 9:04 utc | 31
The trim wheel has a handle that folds out. A possible solution to this problem would be a handle that is extensible, giving a large lever arm, and which functions like a ratchet wrench.
Posted by: Edward | May 26 2019 9:40 utc | 32
Very well noted and thank you for find out mistake.
Posted by: Khin Maung Thwin | May 26 2019 10:07 utc | 33
The worse thing about American politicians is how cheaply they can be bought:
Asking questions and making statements were 39 members of the House – 22 Democrats and 17 Republicans – who during the 2018 election cycle took in a total of $134,749 – or an average of $3,455 each from Boeing in campaign contributions.
Posted by: Ghost Ship | May 26 2019 10:17 utc | 34
>>>> Edward | May 26, 2019 5:40:41 AM | 32
There isn't enough room, which is why they made the wheels smaller in the first place. Perhaps Boeing should switch to side sticks like Airbus.
Posted by: Ghost Ship | May 26 2019 10:32 utc | 35
The structural defects in the 737 NG described so well by b are also relevant to the recent crashes of the 737 MAX, are they not? Several reports indicated that the pilots of the Ethiopian Airlines plane disconnected the MCAS system and tried to trim the aircraft manually but were unable to do so, and this problem with the manual trim system caused them to turn on the MCAS system again, with deadly results. It seems that the 737 MAX is even more dangerous due to its 737 NG legacy. In addition to all the other necessary changes, the manual trim wheel should be redesigned for the 737 MAX, the input from the pilot's yoke should be increased, and a special pilot training category should be established. All of this should have been mandated by the irresponsible FAA long ago. If the needed changes are not carried out, nationwide boycotts of Boeing and of 737 MAX flights should be organized and carried out.
Posted by: Dao Gen | May 26 2019 11:53 utc | 36
Ghost Ship,
That is why I suggested it operate like a ratchet in which the handle can be turned in small increments rather then a full circle:
https://www.youtube.com/watch?v=HJEU0OKA3EM
Another solution could be to attach something like a car jack to the trim wheel which aids in turning it.
Posted by: Edward | May 26 2019 12:07 utc | 37
@Dao Gen - The structural defects in the 737 NG described so well by b are also relevant to the recent crashes of the 737 MAX, are they not?
Yes they are. The MAX crashes revealed that these issues had been 'forgotten'. That is why the FAA is now looking into the NG. I added a paragraph near the end to clarify that.
I once ran "F&E shop, as the Army used to call them. Stands for "fuel and electronic" [repair], sort of a forward operating base shop, these economize the logistics necessary to support fleets. In that context machine parts, subsystems came in and we went through a process of "triage", testing and labeling each unit as it came in. Those units which we judged to be "BER" [beyond economical repair] got labeled as "N.G." (or NFG!) for "no good". Even though the Boeing FUBAR'd 737 is a deadly matter I found the appellation 737-NG to be vastly idiotic and amusing. Similarly amusing when Chevrolet named a car "no va" (doesn't go).
Evidently Boeing ought to have named 737-MAX as 737-NFG.
Posted by: Walter | May 26 2019 12:55 utc | 39
...upon reflection, "737NG" = "737 No Good", and "737 Max" = 737 "No Fly Good", 'or perhaps "Max" = "Machine Actually eXpired"
Posted by: Walter | May 26 2019 13:21 utc | 40
Does the 777 max have any trim systems similar to the 737? Given the 777 has an aluminum fuselage, does this mean the 787 was a mistake?
Posted by: steve | May 26 2019 13:33 utc | 41
Next we’ll learn that the 777 is even worse than this thing & that Malaysian Air’s losses weren’t Israel or the US.Gov’s fault at all, just the few incompetent fools running the biz & the FAA
Posted by: sadness | May 26 2019 13:35 utc | 42
snake @18 said: "Never has there been a better case for independent of government, independent of corporate influence audits."
But what kind of organization could conduct those audits? What can exist that is independent of business and its profit motives, which invite corruption, but also be independent of government while having some mechanism for being answerable to the public? Any effort to create such an organization will just recreate government.
We already have the answer: It is government regulation. We just need a deliberate impenetrable wall between government and business interests like we in America used to have between government and religion. We need to adjust our culture such that any politician promising to be "business-friendly" is as shunned as one promising to implement Sharia law. A revolution could probably accomplish this.
Posted by: William Gruff | May 26 2019 13:56 utc | 43
> The trim wheel has a handle that folds out.
...but it extends alonf the rotation axis, thus
1) it does not extend the "lever asm" (in russia it is called "shoulder" :-) ), just makes a better grip
2) like with piston engines, it has two "dead points (centres)". Piston engines solve it by having multiple pistons working in different phases and by having a flywheel. Both options can not be applied to this 737 wheel.
The video show it is exactly "dead points" that cause problems. When the handle-axis is orthogonal to axis-man, then the wheel is more or less rotated. But those "dead points" progressivle become more and more impassable.
> A possible solution to this problem would be a handle that is extensible, giving a large lever arm,
Would not do.
If it extends parallel to axis - it would not increase lever no matter how long it is.
If it extends orthogonal to axis - it would just get stuck against the wall and FMS stand.
> and which functions like a ratchet wrench.
Yep, or a removable stick, with the wheel having 8 or at least 6 wholes through the wheel's reborde.
This all, whoever, would
1) add extra complexcitiy, increasing weight and malfanction probability.
For example, how would electro-motors act, if the wheel is locked by the said ratchet?
For example, where to store the removable lever, so it would not be a nuisance during normal flights, but in emergency would be both easy to take and reliably fixed until being taken?
2) would probably decrease rotating speed yet more. Force-path trade-off....
Posted by: Arioch | May 26 2019 14:04 utc | 44
@steve Does the 777 max have any trim systems similar to the 737? Given the 777 has an aluminum fuselage, does this mean the 787 was a mistake?
The stabilizer trim via a jackscrew on the 777 is somewhat similar to the 737 though the jackscrew is much bigger.
It can be seen in this video at ~3:00 min: https://www.youtube.com/watch?v=Sy-ARLZXXTA
There are many difference in the trim control. The 777 uses several independent hydraulic circles to run the hydraulic jackscrew motor. The 777 is fly-by-wire. There ar no longer manual trim wheels with long cables running to the stabilizer. All signals from the cockpit are electric to three independent system which then switch the hydraulic circles on/off as needed. There is an electric force feed back to give the pilots some 'feel' for the trim position in their columns.
The aluminum or carbon skin decision is relevant for weight. Carbon is more expensive as special care must be taken for flash impacts and other issues. But it is also a lot lighter that aluminum. The higher price will easily pay off.
There is rightly a focus on the poor quality of work done by the FAA in authorising the Boeing 737 MAX (and, it now appears, that the same could be said about the authorisation of the NG). As stated by numerous articles the FAA were just relying on Boeing assessments and safety checks. However, these weaknesses in the authorisation process should really have been picked up by the European Union Aviation Safety Agency (EASA) and I fail to see how a competent body would fail to do so. So, the EASA is as useless as the FAA, and aircraft certifications are probably politically based rather than a rigorous safety and airworthiness check.
I would imagine that Boeing still intend to have the 737 MAX re-authorised by the FAA within a few months with the expectation that EASA approval will follow shortly after. The political motive will be to maintain the Boeing and Airbus duopoly (for mutual self-interest they both wish to preserve their respective market shares and not significantly challenge the other) rather than issues of safety. As far as I can see there are no politicians in the UK & Europe that are particularly interested or concerned about the issue (unfortunately).
Posted by: ADKC | May 26 2019 14:10 utc | 46
> and a special pilot training category should be established
Posted by: Dao Gen | May 26, 2019 7:53:10 AM | 36
But this is marketing disaster, too train pilots.
- Ok, mr. seller, so we need to spend N hours and M thousand USD to make our pilots efficient at most fuel-economic flight and at pressing automatic take-=off and automatic landing buttons. Good. Make sense.
- Oh, not just that, mr. customer, you also need to spend 10x N hours and 10xM monet to train your pilots against emergencies.
- what emergencies
- Oh, you know, it would not ever be your problem, buyt jsut to make government happy, you nkow, those crazy government clerks shifting responsibilities for life, they want it be passed...
- So what exactly they need be protected from??? And why they make me pay for it?
- Well, you know, 100 years ago once in mankind history an aircraft - not Boeing our competitor's jet it was - it got into X and then Y and wheather was Z and they crashed with all people aboard lost. And then, 99 years ago, there was A and sun was like B and then.... and they crashed and 50% on board lost. And then there was K and if rain goes L and ....
- Okay, okay, got it. Your new Boeing is so unreliable shit, that 100 years later it still can get into X, A and K and everyone dies and our business dies too. And you think i am such an idiot you gonna sell me this unreliable gum-n-sticks shit? I will first buy Manhatten bridge, before i start buying Boeings.
- No! No! our new jets are most reliable! no competitor is so reliable as Boeing! Read out booklet! read the testimonies from our customers!
- But you say our pilots must spend ten times time and ten times money to proitext from X and A and K fatal problems in your Boeing jets...
- NO !!! we do not have those problems! It is government, they always go overcautious and extort!
- So you say there is no X, A and K problems in Boeing? Yes or no???
- A.. a... AH! No, there is absolutely no problems in Boeing jets.
- Good, then if there is no problem, there is nothing to overtrain our pilots at overexpensive courses.
- But government...
- You have problems with gov't - you solve them! You better know what you must arrange with clerks, to fix it. And sto imposing your problems with gov't over us customers. Do you want to sell or not?
- But safety...
- You said there is NO PROBLEMS in Boeing, didn't you???
- Yes, but...
- No buts! Give me an official p[aper that there is no X, A and K problems in Boeing ever, and that if some jet crash and burn i am not responsible, and then we pay for those jets. Or we gonna pay those, who will give us those papers!
Posted by: Arioch | May 26 2019 14:20 utc | 47
Outstandingly well written B; a most impressive explanation of 737 issues.
Two points I would like to add.
1. From my understanding of the design approach of the MAX, Boeing engineers where told to forget physics and focus on FAA compliance with an eye on quick certification and insure no additional pilot training. Example: This is why only one sensor was used. Had Boeing done the right thing, two would have been used, but then the FAA would have needed a lot more time to test. In addition, even now, Dennis A. Muilenburg, the CEO of Boeing is in denial. Just listening to him makes me cringe, he needs to read this article from B and wake the F up.
2. This is terrible timing for Boeing since both the Chinese and the Russians now have aircraft to compete with the 737 MAX. It is extremely difficult to get market share in the commercial aircraft business, but the timing of this disaster will give the competition a fighting chance. In fact I suspect that Airbus competition was not the only factor that made Boeing want to move fast with the MAX aircraft.
In Silicon Valley, if you screw up a business, then you call in your crisis management consultants to fix things. Like the Intel math error in its CPU chips. It is clear to me that Boeing thought it best to save money and not call these crisis experts and it does show. In this case you get what you pay for.
Posted by: Meshpal | May 26 2019 14:24 utc | 48
> The aluminum or carbon skin decision is relevant for weight..... The higher price will easily pay off.
Posted by: b | May 26, 2019 10:06:12 AM | 45
....and then
> Carbon .... special care must be taken for flash impacts and other issues.
So, safety, right?
But, can one trust FAA and Boeing with safety now?
Also, remember recent crash of Sukhoi SSJ in Moscow.
Turn out, when going away from "just works" metallic bodies with inherent Faradey cage properties, properly assessing all possible "what if" scenarios with full respect to possible magnitudes and safety margins, is VERY hard, especially when marketoids demand cutting costs at all costs are reathing over your shoulder.
There was an interesting presentation how nuclear fuel rods geometry is calculated, to tolerate inevitable fuel curving under load. There were safety margings within safety margins, within... Multi-level reservations. And of course there is an incentive to increase efficiency by cutting off some margin, assigned to your unit, because there are several times a margin in other layers.
....and then one day it becomes the anekdot about rakia barrel in a village.
Posted by: Arioch | May 26 2019 14:33 utc | 49
While not a fan of the new Boeing management culture, I would just like to point out that one possible reason you haven't seen any 737NG crashes due to a runaway trim stabilizer is that fact that there is a legal 250 knot speed limit on aircraft below 10,000 feet. Additionally, the older aircraft design was more stable at lower speeds. Therefore if a runaway trim stabilizer did occur, you would theoretically have not reached a high enough speed to freeze-up the the manual trim mechanisms.
In the case of the Ethiopian 737 MAX crash, the speed of aircraft was in excess of 400 knots, where manual trimming was made impossible. In that case the insidiousness and persistence of MCAS would have led to much higher speeds than would be manageable.
Posted by: Michael | May 26 2019 14:39 utc | 50
> This is terrible timing for Boeing since both the Chinese and the Russians now have aircraft to compete with the 737 MAX
Posted by: Meshpal | May 26, 2019 10:24:13 AM | 48
this WAS a terrible timing
China... it seems to have prev-gen much less efficient jet. And one only used with China, so maybe it is equally or yet worse unreliable - there is no 3rd party experience.
Russia... MS-21 is not ready yet. Close reportedly, but just not yet.
SSJ-100 then - talk about timings - just few weeks ago crashed in Moscow after a single lighting strike, with more than a half onboard dead.
So, no, right this vry moment there is no competition from Russia and China.
There were Brasil and Canada - but they were recently bough off by Boeing and Airbus.
There was Ukraine too, but EuroMaidan came and destroyed Antonov corporation as soon as they could.
So, as of this very moment it still is Boeing 737 vs Airbus 320neo duopoly
Posted by: Arioch | May 26 2019 14:39 utc | 51
Excellent work by b. Arioch at 47, That looks like an accurate scenario.
Now would be a good time for the R political party and those among the D Party to repudiate government regulation (as it adversely affects business!) as it relates specifically to the FAA and its "chilling effect" on Boeing. Let business flourish. Let "the market" decide, they say.
The MSM will avoid exposing Boeing issues.
Posted by: fastfreddy | May 26 2019 14:49 utc | 52
I'm thinking that at some point the stabilizer on earlier aircraft was not movable with a pivot point. The elevator alone was enough to move the tail up or down.
If so, what made the aircraft manufacturers feel the need for a pivot to move the entire stabilizer?
Posted by: Bart Hansen | May 26 2019 14:49 utc | 53
Meshpal @48
Russia's MC-21 and China's C919 are both due to begin revenue flights in 2021. Both of these are significantly more affordable than Boeing's 737 MAX family. If the 737 MAX remains grounded for a significant period, or if it requires new type certification then Boeing could be in big trouble. Doubtless the FAA knows this and are thus (again) rushing through the process of trying to get it in the air.
Hey, it is the FAA's patriotic duty, isn't it?
Posted by: William Gruff | May 26 2019 15:06 utc | 54
Arioch,
I wasn't proposing modifying the handle, I was suggesting replacing it with something different, in this case a handle which extends radially and operates like a ratchet.
"how would electro-motors act, if the wheel is locked by the said ratchet?"
The system is designed with a clutch which allows the pilot to manually override the motor.
Posted by: Edward | May 26 2019 15:13 utc | 55
Joe Frasier used to say, "kill the body and the head dies."
How many more Frasier like body punches,as in b's news today, can the giant Boeing absorb before it hits the canvas.
Posted by: morongobill | May 26 2019 15:18 utc | 56
Bart Hansen @53 asked: "...what made the aircraft manufacturers feel the need for a pivot to move the entire stabilizer?"
The aerodynamics of an aircraft change with speed and also with balance... think ten minutes after the coffee is served and a line forms at the restroom. If the balance was always the same (no changes from burning fuel, for instance) and the plane always only flew at one speed (reaches cruising speed before leaving the runway) then it would be easier to design the aircraft to naturally assume neutral level flight without using trim systems. This isn't very realistic, though. As well, while the elevators can do all of the work of raising and lowering the nose of the aircraft, leaving all of the work to the elevators means the pilot will have to be muscling the nose of the plane up or down 100% of the time, which would probably get a little tiring, to say the least.
Posted by: William Gruff | May 26 2019 15:21 utc | 57
> The system is designed with a clutch which allows the pilot to manually override the motor.
Posted by: Edward | 55
Not a clutch, but a switch. A switch that removes ("cuts off") electric power from motor.
The wheel and the motor and the stabiliser are connected by fixed drive train, no clutches.
It is the electric wire - outside of the train - that is connected or disconnected.
if electric power is there - then it is motor, that rotates the said wheel.
if electric power is off - then human can rotate both the wheel and the motor.
A ratchet physically blocks wheel rotation, in one direction, another, or both.
That, a properly functioning ratcher.
If a ratcher is malfunctioning - and device can break - it may become unpredictable.
Boeing clearly tried to keep this wheel-motor-stabilizer drive train "thick as a brick" and reliable as wooden club. Because it is critical safety system.
Introducing a complex, optionally-engaging machinery, retroactivey, into "overcrowded" (no other place for FMC was found) cabin that was designed to have nothing like that - may in total be more dangerous than now.
Posted by: Arioch | May 26 2019 16:08 utc | 58
Thanks, William.
Is a severe mistrim of the aircraft due to pilot error or the STS?
Is the difficulty described by b in correcting a mistrim caused by the greatly differing surface areas of the elevator & stabilizer?
Posted by: Bart Hansen | May 26 2019 16:34 utc | 59
@Arioch @58
Edward at 55 is right. It is you Arioch, who does not know how the 737 trim system works.
There is an automatic clutch between the electrical drive of the jackscrew and the manual drive. In effect the manual over rides the electrical.
There is much more to the total trim system than I wrote down in the above piece. I provided a link at the end to the Stabilizer Trim writeup by the Satguru. It is the best that is out there. Take a few hours to read it and a few days to understand it. Do that before you come here to claim higher knowledge of something you don't know the basics about.
Arioch,
This is what I was told about the clutch on a different blog:
https://www.nakedcapitalism.com/2019/05/how-deep-is-boeings-hole.html#comment-3152331
"The spinning disc is the manual trim wheel. It has a stowable handle that the pilot can use to manually trim the stabilizer if the electric trim is not available. The system is designed such that if that wheel does not turn, the stabilizer does not move. There is a clutch in the system between the electric trim motor and the rest of the system, and this clutch mechanism favors the manual trim wheel. If other methods to cutout the electric trim failed, a pilot could simply place his foot firmly on the wheel and stop its motion, thus stopping the stab from moving further. (The checklist actually says to grasp the wheel with your hand, but the foot works much better)."
Posted by: Edward | May 26 2019 16:55 utc | 61
The effort to computer control and automate aircraft operation serves increased profit motivations. Pilots can be certified with less training. Young pilots work for lower pay as older pilots at higher pay levels retire or quit. As pilots depend on automated computer control, they tend to lose the ability (or were not taught adequately) to react correctly to emergencies.
Look at the difference between the cockpits and instrumentation of the 737 Original and the 737 NG. The NG leans heavily on the dependability of digital LCD computer monitors instead of clusters of independent instruments.
What could possibly go wrong?
Posted by: fastfreddy | May 26 2019 16:56 utc | 62
Arioch @51
"So, as of this very moment it still is Boeing 737 vs Airbus 320neo duopoly"
As it was me that mentioned duopoly @46 I hope you don't mind if I point out that it is not Boeing "versus" Airbus; it is Boeing "and" Airbus - effectively a cartel of two.
This means that the "market" is controlled (rigged) with "understood" market shares and, most important of all, the ability to hack and flag old designs and not have to go to the effort and expense of designing new aircraft.
The avoidance of "designing new aircraft" means that new technology is just hacked on to less than optimum designs and software is just used like wallpaper to cover over cracks.
In my view there are 4 parties to the problem that resulted in the Boeing MAX disasters; these are Boeing, the FAA, Airbus and the EASA.
Posted by: ADKC | May 26 2019 17:24 utc | 63
I recall reading a few years ago about a mine accident in China. The investigators determined that the workers had been complaining about maintenance of the ventilation system having been lax, causing a buildup of explosive dust and gasses, and it was further determined that this had been caused by local mine management determining they could save a few bucks by skimping on maintenance. After the investigation, the "offices" of mine management were ordered moved into the mine, and suddenly safety issues were all promptly addressed. I thought it was an elegant and quintessentially Chinese solution.
Perhaps it should be mandated that all Boeing execs and FAA personnel be restricted to flying only in 737s until these issues become important enough to be addressed.
Posted by: J Swift | May 26 2019 17:28 utc | 64
I get the impression that it is being implied that the force required for operation of the manual over-ride is likely to be greater than what a typical pilot might be able to provide and maintain. This would mean that the so called back up system is itself unworkable or unreliable. Such a claim would hsve to be logged and evaluated if there is any serious effort to monitor and maintain design compliance - assuming it is intended to function.
Posted by: jared | May 26 2019 17:43 utc | 65
Perhaps it should be mandated that all Boeing execs and FAA personnel be restricted to flying only in 737s until these issues become important enough to be addressed.
Posted by: J Swift | May 26, 2019 1:28:11 PM | 64
OK, put the entire board an executive officers of Boeing and the Director General and deputies of the FAA on 10 years full time toilet cleaning duty on 737-MAX. If the 737-MAX ever flies again, that is.
Posted by: BM | May 26 2019 18:13 utc | 66
The post by jared @65 brought a point to mind: Since men tend to have more upper body strength than women, and given the hypersensitivity to identity in western cultures, this means that the 737 NG and MAX designs are sexist and part of The Patriarchy's plot to keep women down. I wonder why nobody in western corporate mass media has yet noted this vulgar display of white male privilege and prejudice that Boeing has crystallized right into the engineering of their aircraft?
Posted by: William Gruff | May 26 2019 18:14 utc | 67
@jared @65 This would mean that the so called back up system is itself unworkable or unreliable. Such a claim would hsve to be logged and evaluated if there is any serious effort to monitor and maintain design compliance - assuming it is intended to function.
Exactly. If the FAA (and EASA) would go by the book, all 737 NG should stay on the ground until Boeing fixed the issue in a safe matter. Not gonna happen as both assume (too) little risk that a runaway stabilizer could happen.
But as Capt Sullenberger says: Nothing is more expensive (to airlines and plane manufacturers) than an accident.
About 30 years ago, an old guy retired commercial airline pilot told me that female pilots weren't strong enough to operate certain controls manually should particular emergency situations arise. Physical body strength was important for safety considerations.
I wonder if this trim stabilizer was what he was talking about. I don't know if these stabilizers pivoted 30 years ago.
Posted by: fastfreddy | May 26 2019 20:10 utc | 69
b, thanks for looking into Boeing and FAA's coverups. Part, or a large part of the US rise was due to its manufacturing power and ability to manufacture good quality products.
The decadence phase or perhaps nearing the end of the decadence phase in the rise and fall of the US empire.
Posted by: Peter AU 1 | May 26 2019 20:25 utc | 70
@69 Stabilators or all-moving tailplanes have been around almost since the beginning of manned (and of course womened) flight..
https://en.wikipedia.org/wiki/Stabilator
Posted by: dh | May 26 2019 20:55 utc | 71
This is excellent article on the 737 NG and Max. Ultimately, these aircraft were designed and assembled in a globalized outsourced duopoly. Rosemount Aerospace Inc makes the AoA Sensor. Rockwell Collins built the 737 Max flight-control computer and wrote the software code that contains MCAS. Government was flushed down the toilet. Effective oversight and regulation ended. Self-certification and “pay to play” are the rule today. Buffoons (Donald Trump and Emmanuel Macron plus Boris Johnson soon) reign over incompetent diminished western nation states subservient to corporate trade treaties, the Five Eyes Deep State and undemocratic super-state institutions. If there is ever a criminal investigation of Boeing for manslaughter, it will find that in order to increase profits, pilots and engineering safety oversight personnel were fired or retired since the merger of Boeing and McDonnel in 1997. Those few who are left, to keep their jobs, never pass their safety concerns on to upper management. To reverse this, CEOs must be jailed for their crimes.
Posted by: VietnamVet | May 26 2019 21:13 utc | 72
> The system is designed such that if that wheel does not turn, the stabilizer does not move.
> this clutch mechanism favors the manual trim wheel.
> pilot could simply place his foot firmly on the wheel and stop its motion, thus stopping the stab from moving further.
Posted by: Edward | May 26, 2019 12:55:13 PM | 61
The question remains though. You propose to augment the wheel with a comples ( = error-prone ) mechanism, which intention is to block wheel rotation one or both directions of the wheel. The very same "foot", but this time made of steel.
One day this ratchet - as everything - would break. In the cabin. Probably, blocking or half-blocking wheel rotation. Without, of course, shouts and fireworks.
Pilots would trust STS or autopilot to move the wheel. So if the wheel does not move, or moves occasinally in one directino then stops - they would consider "this is what STS/autopilot wanted".
STS/AP would issue coimmands at the motor, the commands would be succesflly executed by the motor, but ignored by the drive train, with accordance with Boeing philosophy "human foot is final authority" and "human knows better can always override anything for any reason".
How this situation would develop?
How soon/late pilots would detect it?
How far this would turn stabs before pilots, realising ratchet failure, would hit "trim cut off" and ocntinue flight now unable to turn stabs by neither motors nor wheel?
Posted by: Arioch | May 26 2019 21:21 utc | 73
Typo. Boeing's merger was with McDonnell Douglas. Disciples of GE’s Jack Welch from that defense company took over. They place profit and increasing shareholder value first. This increases their bonuses, too.
Posted by: VietnamVet | May 26 2019 21:32 utc | 74
a reply to > @ Posted by: Bart Hansen | May 26, 2019 10:49:43 AM | 53 about pivoting horiz stabilizer...look at the Wright Flyer... Yup. Pivoting stabilizer.
Videos all of on YT...
Bart wrote:"I'm thinking that at some point the stabilizer on earlier aircraft was not movable with a pivot point. The elevator alone was enough to move the tail up or down.
If so, what made the aircraft manufacturers feel the need for a pivot to move the entire stabilizer?"
As to why, well, it does not add more drag, as well as the several other good reasons.
Posted by: Walter | May 26 2019 22:51 utc | 75
Arioch,
Of course, the ratchet would need to be reliable and not likely to break or fail, just like everything else on the airplane. A ratchet is a simple device and I am counting on a mechanical engineer to design something dependable. I should add that situations where a pilot resorts to the manual trim, such as the Ethiopian Air flight, are rare.
Posted by: Edward | May 26 2019 23:39 utc | 76
@BM | May 26, 2019 3:29:11 AM | 28
Those at the top of both Boeing and FAA also need to be tried for manslaughter and jailed for life.
I would also jail Boeing's previous management (McNerney et al), as they were the ones responsible for the shoddy development of the 737 Max. (Note: McNerney is not an engineer; he studied English and history at Yale, and got an MBA from Harvard.)
The current honchos (Muilenberg etc.) are not innocent, as they did little after the Lion Air crash, and after the Ethiopian Airline crash did all they could to prevent the grounding of the Max -- in spite of hundreds of dead people. So Muilenberg should go to the slammer too.
Of course, some people from the FAA deserve to accompany McNerney and Muilenberg in the ball-and-chain resort.
Posted by: Cyril | May 27 2019 0:05 utc | 77
A probably revealing insight into Jim McNerney's attitude:
Boeing CEO Jim McNerney apologized Friday in a companywide message for telling analysts this week that he won’t retire after turning 65 next month because “the heart will still be beating, the employees will still be cowering.”
McNerney was the CEO of Boeing when the 737 Max was designed.
Posted by: Cyril | May 27 2019 0:23 utc | 78
I belong to a group of ex TN (Trans Australia Airlines renamed Australian in the mid eighties) and have a couple of comments to share plus a link to the facebook page and article
message 1
Darren White: Didn't see anything in the article about the NG's dual function balance/anti balance elevator tabs to give the elevators more 'authority'?
message 2
Neil Tait: Was any attempt made to find the original lost engineering drawings after Lufthansa accecpted the first b737 in 1965?
Link to article and site
https://www.facebook.com/groups/626681970776884/2041696555942078/?comment_id=2042385749206492¬if_id=1558848446463125¬if_t=group_comment
Any answers I can share back wouldbe appreciated, thanks
Posted by: William Hughes | May 27 2019 1:20 utc | 79
Every time it was the stablizer that cause the problem. Air China in 2001. Alaska Airline off the cost of Southern California. Why cant they cut the Stablizer up into 5-10 pieces each control by a separate jackscrew so the pilot can manually trim them.
Posted by: Joenobody | May 27 2019 8:19 utc | 80
I am sure they are in discussion with faa and esa to ensure that the plane is in the air again pronto. We will get a negotiated redesign.
Posted by: jared | May 28 2019 3:26 utc | 81
You can't hack an old design (on anything, especially aircraft) without accepting that you are trading off that which is optimum for the sake of cost. And you can't keep on hacking old designs without introducing unnecessary complexity and unnecessary inefficiency - increasing the level of risk. You have to accept that hacking old designs, at some point, simply will not work. And then you have to ask yourself at what point Boeing will stop hacking the 737 design? In my view the 737 design has reached the end of the line. The best that Boeing will come up with for the 737 MAX will be just another hack.
Posted by: ADKC | May 28 2019 8:38 utc | 82
@William Hughes @79
I don't know anything about the "lost drawings".
Elevator tabs are supposed to increase elevator control, or, said differently, make it easier to (manually) move the elevator. They are, to my best knowledge, used on all 737 types and thus not relevant to the discussion of NG differences.
Article at Counterpunch for which I won't post a link, but it is entitled The Boeing Way: Blaming Dead Pilots
Posted by: nwwoods | May 28 2019 14:40 utc | 84
OK, I'll post the link
https://www.counterpunch.org/2019/05/24/the-boeing-way-blaming-dead-pilots/
Posted by: nwwoods | May 28 2019 14:43 utc | 85
William Gruff @57
Could you not have a similar system to "Servo assisted steering" in a car, to help the pilot push and pull the stick? (I take it that the stick in front of the pilot(s), is what controls the elevator?)
Additionally, I do not understand why the elevator is not pivoted at a neutral position where the force of the wind tending to increase the angle of attack and the force tending to decrease the angle of attack balanced.
(In case it is not clear what I mean, imagine a fin which is pivoted about its leading edge. It will always push against any attempt to turn it out of a neutral position. Now imagine the same fin, pivoted about its trailing edge. This will tend violently to go in either direction, if it is turned ever so slightly out of the direction of travel of the air going past it. Somewhere in the middle there should be a point where you can pivot it so that the force tending to increase the angle of attack is equal and opposite to the force tending to decrease the angle of attack. Shouldn't there? Don't large ships' rudders have an exactly analogous system? With a small rudder that turns the main fin which is pivoted about a neutral point?)
Posted by: foolisholdman | May 28 2019 20:54 utc | 86
William Gruff @57
Another thought, could you not have a small, manually-controlled electric motor (With a three-position switch, ON CW - OFF - ON ACW, geared to the wheels in the cockpit? It could easily exert more force than a man and in case of power/motor failure, you could still have your crank handle.) Or come to that, a connection to the motor driving the jack-screw that allowed the pilot to switch off the autopilot connection to the motor and connect a switch that allowed the pilot to control the jack-screw motor directly.
Posted by: foolisholdman | May 28 2019 21:33 utc | 87
Thank you b I have copied this back to the tn site.
Posted by: William Hughes | May 28 2019 21:58 utc | 88
b,
Back after the Memorial Day weekend and reading your May 25, 2018 “...Severe Problem...” article, and comments, I was tempted to quote back to you your comment 60 words, “ It is you...who does not know how the 737 trim system works.” But you do know, at least to the extent your reading of your sources informed you, how that particular type trim system works. What you appear to not know is how trim systems work, what they do, how and why, and how to use a trim system in an aircraft. In this you are like the two pilots who crashed 737 MAX8 aircraft, who also did not know the basics. You are not a pilot, or responsible for the lives of passengers who have entrusted themselves to your supposed knowledge and skills, so your lack of understanding is not only understandable, but not in their league. For the record, if those pilots had had basic competence they would not even have known the MCAS system was active on their aircraft, because they would have been ahead of it: Any time you get a stall warning the automatic first response needs to be stick (yoke) forward, add ten knots (or more), then stabilize the aircraft in flight, and then look for the cause.
A cardinal rule of piloting is “Fly your aircraft”. That is a 'first tranche’ rule. Below it, and necessary to following it is “know how to fly aircraft”, and below that is, in ‘third tranche’ position, the primary rule: “Know how aircraft fly.” Aircraft are real-world anti-gravity devices. In the real-world anti-gravity is accomplished by manipulating existing components of physical reality using natural characteristics found in those and interactive physical correlations designated ‘natural laws’.
Trim tabs deflect airflow. Trim tabs differ from elevator tabs, and rudder tabs, which are what do actual flight-surface manipulating on large commercial aircraft, whose rudders and elevators are bigger than houses. Trim tabs are for ‘trimming’, not moving the surfaces. They are not for flying the aircraft. You position a trim switch, turn a trim wheel, or crank in trim to neutralize a control pressures in specific configuration situations. You do that so that you do not have to hold a constant pressure against a main control device to maintain an intended path of flight.
A “runaway trim tab" is a mechanical failure. It means something went wrong. It is not a normal configuration for the aircraft. Correction is required for the effect of the condition that results. Correction is a compensation procedure. Resolving a trim tab locked against a stop is done by, as you note, but fail to notice, overpowering the fault result using primary control.
You write: “In case of a mistrim of the stabilizer, the plane puts its nose up or down and the pilot will have to push or pull his column to move the elevator to counter the mistrim of the stabilizer.” That is correct, and as you can see rereading, corrective input is exerted by use of a primary control. You write also: “Depending on the position of the stabilizer and the speed of the airplane this can require very significant force.” Correct, sometimes, again, in very unusual circumstances. The competent pilot has a number of options in such a case. First is, of course, counter-action through a primary aircraft control. He may also change the speed of the aircraft, and change, within limits (some of which depend on speed), changeable flight surface configurations (flaps, snoots, raise or lower gear, etc. Notice that, here, we have not touched trim. It is upon having corrected the condition that trim is turned to, to relieve the amount of primary control pressure required to maintain the desired, or required, aircraft flight situation.
Remember the rule “Fly the Airplane”? That is done with primary flight controls. And always first. It means, in any abnormal situation, place the aircraft in a fully flying attitude, safely within the flight-envelope the aircraft is designed to operate within. There is an airspeed designated “maneuvering speed”, sometimes “penetration speed”, because it is the speed recommended for storm and turbulence penetration. It is the safest speed in the aircraft’s flight envelope, and has a wide margin around it (in case of instrument error). It is the speed to which a pilot should slow, or accelerate, if he is not reasonably sure what sorting a problem will require, he should put the aircraft when dealing with an unusual situation. Note, however, that once a pilot has returned his aircraft to normal flight in whatever an occurrence the aircraft should be flying and flying, will be under control.
The pilot can then exercise options to make holding the established flight condition easier. The hack pilot can put a crow-bar in the crank on his trim wheel and reef, maybe stretching a cable, hopefully not breaking one, which would put him back at square one. The competent pilot will have already tried the electric trim and, that not working, killed the power to the electric trim and has started looking for the cause of the abnormality, and if the tab is locked at a stop-block, means to return it to range, all the while holding the aircraft in stable flight manually, with primary controls. If the cause of the trim going to stop is the butt of the stewardess on the copilot’s lap being against the copilot’s trim switch, the pilot may resolve the issue by asking her to move her butt. Note that he does not stop flying the aircraft: He does not let go the controls to start pushing, letting the aircraft go into a dive, or nose up to stall for the mistrim. If the cause is the.trim-switch lever having broken and the nub having snagged against its housing, he may fly the airplane by turning the primary control of the aircraft over to the copilot while he pries the broken switch loose and to neutral with a tip of his pilot’s wings pin, then switch power back on and see if the electric trim is usable again. If the electric trim is out of commission, or shorted and the motor is jacking the screw against the stop, he can take control of the aircraft back from the copilot and go to override procedures. Note that in all cases this is not an emergency, it is a mechanical failure. In an emergency the pilot would ignore the troubleshooting until the emergency condition was resolved, using the primary controls.
Do you understand? A trim system is not a primary control system. It is a pilot strain relief system. Having a trim wheel the size of a ship’s wheel, with or without lashing-pins around the rim, is not necessary, nor would be advantageous for safety. Excess leverage in the hands of idiots is always dangerous; they try to muscle through problems and breaks things. Break the trim wheel system trying to correct an electrical fault caused “severe mistrim” and you have two mechanical problems (three counting the idiot). Better would be to leave the idiots in a simulator diving seven thousand feet to relieve an aerodynamic block on a trim tab. Never let such a one near a real airplane, especially one with passengers. Thinking about such ones reminds me of a couple of transmission mechanics who were marveling at an idiot in their business who had broken a shoulder rolling a transmission off a jack trying to install it, for rocking the thing too much trying to get a bolt’s thread to start. “You only rock ‘em a half-inch at most." one said. “More like a quarter at the bolt-hole." the other said. What the hell was the guy doing rocking enough to fall off the jack, both were wondering. It’s the same thing relieving aerodynamic blocking: At ten thousand feet you have a thousand feet vertical clearance to bobble your aircraft in, five hundred up, five hundred down. above and below that space, at odd thousands, eleven and nine, is oncoming traffic airspace. Going down seven thousand feet from ten thousand is equivalent to driving across three parallel two-lane highways, coming out at three thousand feet, an odd thousand, is into the oncoming traffic lane of a fourth two-lane highway (“Well, mu’ pickup was pullin’ lef’, so cousin Earl was gonna toe 'er in some, so he was on the fender reachin’ down to turn the steering knuckle, an’ I was turnin‘ across to the pull side, to relieve the tension on the knuckle, so he could turn it with the short wrench was all we had... Was the fender he was on the dump-truck clipped, so I s’pose he’s on the front of the dump-truck now... Dammit, if we’d a’ had a longer wrench...”). These guys could be pilots, according to your source.
The same as you only have to rock a little to relieve friction-binding on a bolt-hole, you only have to dip a little to relieve aerodynamic force on a flight surface. So you only get an eighth turn in a short relief, instead of a half or three-quarter turn. You can slow to gear speed and lower your landing gear and slow your pick up of speed to give yourself more time. Extend flaps and get more time, maybe get slow enough you don’t need to flap your tail. And you don’t have to only come back to level, point it up and take it up two hundred and start pulling the slack on the wheel while coming to level, grab some more going down two hundred, then go up four hundred amd do the same again. Little dips too much like some dinky small-towns circuit truck-n-trailer carnival roller-coaster for you? Go on your radio and get a flight-level, say, twenty, or twenty-two, those go the same direction as ten thousand feet, and you get two thousand feet to whoop and roller-coaster in, a thousand up and a thousand down, providing any traffic at levels nineteen and twenty-one are not roller-coastering, too, and coming down toward you on a collision sine-wave...
Once you are back in range on the jack screw the trimming should be normally easy again. Unless you bent something, or jammed threads on on the screw.
In the end, what is really good to know, because it is the most scary part of all that has been brought forward by the Boeing 737 MAX8 pilot-error crashing, and aftermath of mindless-media blabber-flapping, is that the two who crashed, and horrible to think how many more, who are half-trained and don’t know a stall when they are in one, are piloting passenger-carrying airplanes.
At least, in their huffing and puffing and making themselves your sources they are revealing themselves improperly trained huffer and puffer nonsense and hysteria fueled incompetents with no idea how airplanes fly, or how to use controls correctly. In the air ones like those are one unexpected event and resulting mentally paralyzing shock reaction, from destroying whatever aircraft they may be flying, and killing all passengers who entrusted themselves to their incompetences.
Blame the FAA! Blame Boeing! Don’t blame the incompetents who crashed the two aircraft, who should have been doing what the MCAS computers did before those computers did, since they have inbuilt lag-times. Lower the nose, pick up airspeed at first warning of stall, especially on take-off. Fly the Airplane (or re-fly it, if you have already stalled it), then look for irregularities.
Posted by: EV | May 30 2019 0:31 utc | 89
You Said:
The changes from the 737 Classic to the 737 NG make it more difficult, if not impossible, for the pilots to recover from such a situation:
The smaller manual trim wheels on the 737 NG make it more difficult to trim a runaway stabilizer back into a regular position.
The larger stabilizer surface makes it more difficult to counter a runaway stabilizer by using the elevator which was kept at the same size.
737 NG pilots no longer learn the rollercoaster maneuver that is now the only way to recover from a severe mistrim.
BUT - NG HAS THE SAME RECOVERY ISSUES ! As in NO recover means to recover -
It has virtually the same size trim wheel with 1/2 the turns lock to lock = same or more rate - the smaller wheel mitigates the tail plane differences
Boeing HAS NO DATA to simulate the trim wheel force VS MACH and never has - this is why the stone walling on the simulator data
traditionally they have the three second rule - "dont dive for more than three seconds" or ... well we know what can happen ..
now like the MAX AOA vane, lets talk about systems integration (again) with the trim wheel - the question is - how to crank 100+ pound trim wheel force while you are holding a stick in your gut, in a 4 point harness and G-d forbid negative G's - or worse, pilots floating out of their seats or stuck to the over head panel and worse case - a "diverse" 80lb female ? From whence does though react thy force ?
Posted by: mortimer snerd | May 30 2019 5:17 utc | 90
@EV That is quite a long comment with lots of nonsense.
What you appear to not know is how trim systems work, what they do, how and why, and how to use a trim system in an aircraft.
I do now the hows and whys of a trim system.
For the record, if those pilots had had basic competence they would not even have known the MCAS system was active on their aircraft, because they would have been ahead of it: Any time you get a stall warning the automatic first response needs to be stick (yoke) forward, add ten knots (or more), then stabilize the aircraft in flight, and then look for the cause.
The pilots were competent. They did not crash the plane, MCAS did that.
When the stall warning (stick shaker) went off it was obvious to the pilots that the plane was not stalling. A view out of the window was enough to recognize that. That made the stick shaker alarm an "Unreliable Airspeed" (UAS) event. This happen shortly after start during the climb out in mountainous terrain. Putting the stick forward in that situation was not a good option. The speed setting was also already high enough.
There is also no way that this could have avoided the MCAS intervention.
Trim tabs deflect airflow.
The 737 has no trim tabs. It has elevator tabs which have a different purpose than trim tabs.
The rest of your comment is largely bollocks that has nothing to do with the flights that crashed or the content of my piece.
Lots of words to blame the pilots who were fighting a plane that failed them.
b,
Sorry to offend you with too much explanation. None would have worked as well. apparently. What I was trying to say was that airplanes are flown with primary controls, not trim, which is for easing pilot physical workload.
Where a horizontal stabilizer is adjusted for trim the whole horizontal stabilizer is a "trim tab", with a limited range of adjustment the stabilizer is a "flying tail" of a limited type (on a full "flying tail" the elevator control does what the 737 trim screw does). Airplanes fly for deflection of airflow. All flight control surfaces deflect airflow.
I study "HAL Effect". My term "HAL Effect" is from the "HAL 9000" 'Logical Intelligence Device' projection of Stanley Kubrik's "2001: A Space Oddyssey".It is product of giving too much control to mechanical intelligence. I looked expecting to find the MCAS system to have crashed the 737MAX8 airplanes. My initial premise was your "They [the pilots] did not crash the plane, MCAS did that."
The physics involved did not sustain, do not sustain, that premise. The pilots stalled the airplanes. I do not know if an MCAS system could, or, modified, will be able to, unstall an airplane. In the 737MAX8 take-off stall events of discussion, with the pilots holding the elevators in stall, the MCAS obviously could not and the aircraft stalled in.
Explaining this would be explaining fundamental basics of heavier than air flight, which would take too many words. Basically, all stalls are relative, the relationship being between aircraft and airflow Aircraft (wings) do not stall all at once, or all the same, but all will stall in any spherical azimuth position, even going straight down with gravity aiding acceleration to and past all limits. An aircraft cannot be pulled out of a stall-dive until the wings are unstalled. The "view out of the window" will tell you nothing (or it may confuse you, or give you a false sense of confidence. It is the direction of travel relative to the plane of the wing, not to the landscape that defines a stall.
I stand by my reaction-response to stall warnings. And by my assessment of 'pilots' who dismisses "stick shaker alarm[s] [as] an "Unreliable Airspeed" (UAS) event[s]." They need HAL 9000s to decouple their controls (so they can't hold the column back to maintain their stalls) and fly their aircraft for them.
Even with the 737MAX8 examples arguing against me, I remain leery of shifting pilot in command responsibilities to HAL 9000 'More Logical than Us' devices, or their latest evolution Darwinian ancestors (which the current outcry appears to be demanding Boeing softare engineers to supply so that 'Monkeys, Too!' will have equal right to aspire to be pilots.
Posted by: EV | May 31 2019 0:07 utc | 92
@ EV with his response back to b at #92
EV wrote at the end
"
Even with the 737MAX8 examples arguing against me, I remain leery of shifting pilot in command responsibilities to HAL 9000 'More Logical than Us' devices, or their latest evolution Darwinian ancestors (which the current outcry appears to be demanding Boeing softare engineers to supply so that 'Monkeys, Too!' will have equal right to aspire to be pilots.
"
Your argument made sense until the part where you put the blame back on specific humans with your derisive 'Monkeys Too!' blaming shift. Why are you not putting the blame on the corporate system that is challenging your "job lock" because of profit instead of the poor dead pilots that are, at a minimum, serious victims of corporate greed along with the other passengers. Why are you not reading the latest admittance from Boeing about documentation/training inadequacy?
I posit that you have an agenda and are paid to come here and troll your position hoping it sticks to the propaganda wall of obfuscation of the real problem. I think you will fail and thanks for the opportunity to show your comment for what it is.
Posted by: psychohistorian | May 31 2019 2:04 utc | 93
EV @92 sez: "The pilots stalled the airplanes"
You are factually incorrect (what is commonly referred to as "lying").
Neither of the aircraft that the MCAS system flew into the ground stalled.
Let me repeat that as it is an important point: THE CRASHED 737MAX AIRCRAFT DIDN'T STALL
Did you fabricate that part about the crashes yourself or is that a "mistake" that some corporate mass media fake journalists made that you are repeating?
Posted by: William Gruff | May 31 2019 10:34 utc | 94
Psychohistorian (93),
I will admit a bias against 'equality' agendæ that deprecate education and standards to achieve the "equality" they define to standards set by political true-beliefs. But I do not have any agenda, myself, nor am I paid for anything. I did not blame "corporatee greed" because it was not involved. he current course Boeing appears to be taking looks to me to be appeasement, to appease the media, who, as you demonstrate, have taken up "corporate greed" as you demonstrate, as Crusaders took up the cross, to mob against and club down others. My view in this regard is that Boeing should recover for losses and damages from the Media, who have carelessly and willfully mobbed to lynch, without any effort to determine if it was Boeing who raped Miz Sally, or if they's jus' riled theyselves on rumors.
The reason I blame "the poor dead pilots" is because they murdered three hundred plus people playing "cowboy-pilot" flying between stall-warning and stall, and, for that, all other factors aside, getting into stall situations, and not unstalling (not knowing to unstall?).
William Gruff (94)
You need to learn about stalls and all the ways they may occur, including hitting sinks (down-current air) at very near to stall speeds, where the sudden change of flight angle, caused by the sinking, can change the angle of attack enough to cause stall. What is called 'wind shear' will also cause stall, but by leaving the aircraft suddenly below stall speed relative to the entered slower-moving air.
The MCAS systems did not fly the aircraft, they only exacerbated the problems the pilots got hemselves into.
Also, scientifically, and legally, and morally, there is a difference between being factually incorrect and lying. Lying requires a willful component, and a maicious component.
Posted by: EV | Jun 6 2019 0:15 utc | 95
As an Aeronautical Engineer, trained to become a pilot in Piper Cub, T-28, and T-33 aircraft in the Air Force, class of 57H Class....flew T-33, F-84, and F-86H in the Mass. ANG; and finally owned and flew a Cessna182 aircraft... total of 50+ years of flying. Before I actually flew any and ALL the aircraft I flew, I learned EVERYTHING about the aircraft BEFORE flying it.... including 'blindfolded' cockpit checkout. Simulators are a GREAT tool for pilot training.... HOWEVER, flying the airplane is the ONLY way to REALLY get to know the airplane. As I understand it there is very little ACTUAL pilot training flying time given individuals to become a pilot these days! So, I conclude the pilots flying the 737Max aircraft Did NOT have the proper training to cover ALL the emergency situations that could cause the aircraft to NOT be controlled safely.... REALLY need to fix that BAD situation...Amen, AMEN, and AMEN!
Posted by: Joel Godston | Jun 23 2019 5:19 utc | 96
The comments to this entry are closed.
I feel as though I've read an expert's analysis on the Boeing 737 problems.
And a very clearly written one indeed.
Thanks.
Posted by: JOHN CHUCKMAN | May 25 2019 22:11 utc | 1