Boeing 737 + Congressman Carson = misery

[BugI02]

Some new info

https://www.bloomberg.com/news/arti...rs-still-seek-key-part-for-clues?srnd=premium

One of two sensors known as angle-of-attack vanes, located near the nose of the aircraft, would have to malfunction or be damaged to cause the scenario suspected in the crash. Searches of the wreckage as of Thursday night had failed to locate the part believed to have been involved, said one of the people.

Evidence from the flight-data recorder of the Ethiopian 737 Max 8 showed that the missing sensor was malfunctioning and that a device known as a “stick-shaker” -- which makes a loud nose and rattles a pilot’s control column to warn of an impending aerodynamic stall -- had been activated on the same side of the aircraft. It could be heard on the cockpit voice recorder, the person said.

https://www.nytimes.com/2019/03/29/...tion=click&module=Top Stories&pgtype=Homepage

Angle-of-attack sensors are highly reliable and have been used on passenger jets for years, but like any aircraft component, they can fail. Given that, former Boeing and Rosemount engineers said it was surprising that Boeing would allow a single sensor to activate a crucial system that pushes the aircraft toward the ground.


The sensors, which are effectively wind vanes on the jet’s nose, have malfunctioned in the past, for a variety of reasons, including bird strikes, according to the former engineers. They have also been broken by jetways that attach to the plane for passengers to board and exit the plane.

The NYT article raises an interesting point. The mounting point for the AoA indicator is the same for the MAX and the 737NG (see the round black circle just behind where the radome joins to the fuselage, even with and below where the side windows meet the windshield). The fuselage on the MAX8 has essentially the same dimensions as the 737-800NG (very tip of rear fuselage sticks out a few more inches but not germane to this discussion)

View attachment 76034


But the inlet edge of the engine sits 7 inches further forward because of the bigger engine and changed geometry of the engine pylon. That would force the jetbridge location to be changed somewhat, too. This isn't the best quality picture, but it was one of the best I could find to show how close the weather curtain sits to those flight sensors (Norwegian Air Max8 at the gate)

View attachment 76033

It is possible during normal jetbridge movement that the AoA sensor was struck and damaged on both aircraft. The Capt's sensor is on the same side of the a/c as the jet bridge. I'll be interested in knowing if the bad sensor was on the left on both doomed a/c

 

[Spear Dane]

How much has been focused on the Ethiopian Airlines co-pilot and the fact that he had about 200 hours flight time, don't know about the pilot.....

Totally unsurprised. About a billion years ago when I was learning to fly we had a young Korean learning at the same FBO I was taking lessons at. Nice guy, had a degree in something or other. Was hired by KAL straight out of school, sent to America, Tulsa to be exact, was paid and had training paid for as well, all so that he could get his instrument, commercial and multi ratings and go back to Korea and go right seat in an A320. Yep, zero to one heartbeat away from pilot in command of a 250 pax jet in less than 400 hours. If it's not from a first world western country I don't fly it. Russia is not a first world country and Aeroflot is right out.

 

[BugI02]

I always feel sorry for people I know whose work takes them to sketchy third world countries. Sometimes they don't have a choice to use first world providers, and I know they have a definite hierarchy of what companies are the best of the rest

I know one guy whose employer sends him to the 'stans pretty regularly ... ugh! He's making boss book, but I think I'd look for other employment before the roll inevitably comes up snake-eyes

 

[SheepDog4Life]

Training takes time/effort and......wait for it..."MONEY" Always follow the "MONEY"

This...

Totally unsurprised. About a billion years ago when I was learning to fly we had a young Korean learning at the same FBO I was taking lessons at. Nice guy, had a degree in something or other. Was hired by KAL straight out of school, sent to America, Tulsa to be exact, was paid and had training paid for as well, all so that he could get his instrument, commercial and multi ratings and go back to Korea and go right seat in an A320. Yep, zero to one heartbeat away from pilot in command of a 250 pax jet in less than 400 hours. If it's not from a first world western country I don't fly it. Russia is not a first world country and Aeroflot is right out.

And, this...

 

[ATOMonkey]

Some new info

https://www.bloomberg.com/news/arti...rs-still-seek-key-part-for-clues?srnd=premium






https://www.nytimes.com/2019/03/29/...tion=click&module=Top Stories&pgtype=Homepage




The NYT article raises an interesting point. The mounting point for the AoA indicator is the same for the MAX and the 737NG (see the round black circle just behind where the radome joins to the fuselage, even with and below where the side windows meet the windshield). The fuselage on the MAX8 has essentially the same dimensions as the 737-800NG (very tip of rear fuselage sticks out a few more inches but not germane to this discussion)

View attachment 76034


But the inlet edge of the engine sits 7 inches further forward because of the bigger engine and changed geometry of the engine pylon. That would force the jetbridge location to be changed somewhat, too. This isn't the best quality picture, but it was one of the best I could find to show how close the weather curtain sits to those flight sensors (Norwegian Air Max8 at the gate)

View attachment 76033

It is possible during normal jetbridge movement that the AoA sensor was struck and damaged on both aircraft. The Capt's sensor is on the same side of the a/c as the jet bridge. I'll be interested in knowing if the bad sensor was on the left on both doomed a/c

Very good observation on the jetway possibly damaging the sensor! Especially since it's always (so far anyway) the left side sensor that has failed.

In my experience failures are usually the result of a result of a result of an unintended consequence.

 

[avboiler11]

Looks like the Ethiopian crew did in fact turn off the Stab Trim Cut-Out switches...only to turn them back on.

https://www.wsj.com/articles/ethiop...y-steps-to-disable-737-max-system-11554263276

“After turning off a flight-control system that was automatically pushing down the plane’s nose shortly after takeoff March 10, these people said, the crew couldn’t get the aircraft to climb and ended up turning it back on and relying on other steps before the final plunge killed all 157 people on board."

"The pilots on Ethiopian Airlines Flight 302 initially reacted to the emergency by shutting off power to electric motors driven by the automated system, these people said, but then appear to have re-engaged the system to cope with a persistent steep nose-down angle. It wasn’t immediately clear why the pilots turned the automated system back on instead of continuing to follow Boeing’s standard emergency checklist, but government and industry officials said the likely reason would have been because manual controls to raise the nose didn’t achieve the desired results.

After first cranking a manual wheel in the cockpit that controls the same movable surfaces on the plane’s tail that MCAS had affected, the pilots turned electric power back on, one of these people said. They began to use electric switches to try to raise the plane’s nose, according to these people. But the electric power also reactivated MCAS, allowing it to continue its strong downward commands, the people said."

 

[BugI02]

I read this also, but cannot think of a reason why that wouldn't work without some other failure in the actuator(s) for the elevator. If I understand correctly, there are two switches which both have to be disabled to neutralize the system. Do you know what would happen if only one were neutralized - perhaps only the side experiencing stick-shaker activation? Is it possible they thought that deactivating say only the captain's electric trim would be enough to stop the erroneous input to MCAS? Because as I understand it, the FMS takes input directly off the AoA indicator and there is no way to switch indicators to one that is not compromised thus necessitating disconnecting both electric trim circuits. Is it possible they misunderstood the procedure

Have they released the whole FDR report yet, or is it still just talking points

Did you see that the Lion Air a/c had a refurbished AoA from a facility in FL. It makes me wonder why a four month old a/c already needed a replacement AoA indicator and makes the ground damage theory seem more likely to me

 

[BugI02]

https://leehamnews.com/2019/04/03/et302-used-the-cut-out-switches-to-stop-mcas/
ET302 used the Cut-Out switches to stop MCAS

The information around the ET302 crash, which comes forward piece by piece, points to an almost identical chain of events to JT610. It also points to the pilots being briefed and, to the knowledge we have available, following procedures including the procedures for a wild running MCAS.
How could ET302 then crash? The FAA and Boeing issued an Airworthiness Directive 2018-23-51 on 8th of November 2018 on what Emergency checklist to use to avoid another MCAS caused crash? The crew should execute the “Trim runaway” emergency checklist.
So why didn’t it work, if the crew indeed followed this AD? Here’s why:
Two weeks ago I wrote: the flying with a full nose down Horizontal Stabilator trim was possible on a 737. The pilot could control the aircraft with his elevator control via the Yoke, even against a full nose down MCAS trim. This was verified in a 737 simulator by a US airline. At the time, I asked what the flown speed was? The answer I got was; the typical speeds after Taking Off.
In subsequent discussions with MentourPilot, a YouTube channel with millions of viewers, I was informed this would probably not be true for higher speeds. MentourPilot’s experience when examining hundreds of pilots as Type Rating Examiner for the 737 was the elevator got exceedingly heavy at higher speeds and manual trimming at the slightest miss-trim of the Stabilator from neutral Yoke forces was very difficult

Combined with the speed which follows from an “IAS disagree” Emergency checklist procedure the Pilot Monitoring (PM) could have problems to move the trim while Pilot Flying (PF) would fight to hold the Yoke against the elevator forces. At a larger miss-trim, the situation is unattainable.
The excessive manual trim forces have been confirmed by an airline pilot which has done 737 test flights after elevator maintenance, where manual trimming needs to be checked. At a miss-trimmed Stabilator, you either have to re-engage Electric trim or off-load the Stabilator jackscrew by stick forward, creating a nose-down bunt maneuver, followed by trim.
Stick forward to trim was not an option for ET302, they were at 1,000ft above ground. According to The Wall Street Journal, the ET302 crew re-engaged electrical trim to save the situation, to get the nose up. It was their only chance. But too late. The aggressive MCAS kicked in and worsened the situation before they could counter it.

 

[avboiler11]

It has been YEARS since I was anywhere near a 727 sim, and have never flown a Guppy, but allegedly at higher airspeeds manually manipulating the trim wheel can be difficult.

Or course Mother Boeing saw fit to put a flip-out handle on the trim wheel...curious if it was utilized.

Also have seen some speculation that perhaps the low experience FO was trimming the improper way, but again that is NOTHING but conjecture at this point.

The fact the memory item was complied with is important though...

 

[BugI02]

I'd like to know if MCAS is enabled even if the autopilot is not; and though I don't know how much altitude they might have lost in their battle with the trim, being on autopilot at 1000 AGL seems a bit too much like engaging autopilot as soon as you have positive rate - which is to say too early. Being an old-timer I was taught by even older old-timers. What was drilled into my head was if the airplane was performing normally, don't be in a hurry to change anything until you had some useable altitude underneath you

 

[avboiler11]

Our SOP is min AP engagement altitude of 500’ AFE, a recent change down from 1000’ AFE.

Culturally, nobody engages THAT low unless workload is very high due to some abnormal, convective weather, PF is just exhausted or most likely you’re on an RNAV SID which requires AP use.

 

[BugI02]

https://aviation.stackexchange.com/...ance-system-of-the-b737-max-8-be-overridden-b
Can the autopilot (or stall avoidance system?) of the B737 MAX 8 be overridden by sheer force?

7
Most transport category aircraft, including B737, have the elevator, the main surface controlling pitch, attached to a horizontal stabilizer that is also movable. The elevator is controlled using the control column (yoke), while the stabilizer is moved using the trim wheels on the central console.

This arrangement means the command from the elevator is added to the command from the trim. So when the trim is all the way pitch down, the maximum pitch up command the elevator can provide before it hits its mechanical limit is severely limited.

Autopilot: Yes, but…
The autopilot moves the elevator instead of the pilot, and in B737 the yokes actually move as it does so. So the pilots can pull on the yokes to override it. As already mentioned in another answer, the autopilot is limited to force of 25 lbs, so even if it does not disconnect when the pilots apply 21 lbs as designed, they should be able to overpower it—and 25 lbs should not need one to brace too hard anyway.
However, the autopilot also actuates the trim occasionally to transfer the needed pitch command from the elevator to the stabilizer. This reduces drag a bit by eliminating the angle between the stabilizer and elevator, and it means the aircraft will continue to fly straight when the pilots disengage the autopilot.
But it also means the aircraft will be trimmed in whatever way the autopilot left it. If that means it is trimmed far in one way, the pilots ability to give the opposite command with the elevators alone is limited and they need to move the trim too.


MCAS: No
The Maneuvering Characteristics Augmentation System, however, works differently. It does not do anything at all with the elevators and simply adds nose-down trim. If it malfunctions, it will move the stabilizer all the way to the mechanical stop, and in this trim position, the elevator does not have enough authority to keep the nose up at slower speeds.
The yoke will hit mechanical stops at large, but still reasonable force (IIRC 40 or 50 lbs). All the hydraulic cylinders will be at their mechanical limits as well, so applying more force won't help. The elevator can't go any further. The only remedy is to turn off the electric trim—which is used by the MCAS, and by trim switches on the yoke—and adjust the trim using the trim wheels.

 

[Blackhawk2001]

Some new info

https://www.bloomberg.com/news/arti...rs-still-seek-key-part-for-clues?srnd=premium







https://www.nytimes.com/2019/03/29/...tion=click&module=Top Stories&pgtype=Homepage




The NYT article raises an interesting point. The mounting point for the AoA indicator is the same for the MAX and the 737NG (see the round black circle just behind where the radome joins to the fuselage, even with and below where the side windows meet the windshield). The fuselage on the MAX8 has essentially the same dimensions as the 737-800NG (very tip of rear fuselage sticks out a few more inches but not germane to this discussion)

View attachment 76034


But the inlet edge of the engine sits 7 inches further forward because of the bigger engine and changed geometry of the engine pylon. That would force the jetbridge location to be changed somewhat, too. This isn't the best quality picture, but it was one of the best I could find to show how close the weather curtain sits to those flight sensors (Norwegian Air Max8 at the gate)

View attachment 76033

It is possible during normal jetbridge movement that the AoA sensor was struck and damaged on both aircraft. The Capt's sensor is on the same side of the a/c as the jet bridge. I'll be interested in knowing if the bad sensor was on the left on both doomed a/c

My wife worked for an airline some years ago and was trained to operate the jetway. She had to get within 1-1/2 inches of the door, but if she got within 1 inch, it would be assumed that the jetway had made contact with the aircraft and it would be grounded. Again, we're talking about a foreign airline and its procedures in this instance, but my wife's training indicated that the airlines were well aware of the dangers of the jetway entrance in proximity to the aircraft fuselage.

 

[BugI02]

https://www.zerohedge.com/news/2019...iled-do-one-thing-could-have-prevented-deadly
Experts Say Ethiopian Air Pilots Failed To Do One Thing That Could Have Prevented Deadly Crash

Now that air-traffic security experts have had some time to peruse Ethiopian Airlines preliminary report on the deadly crash of flight EET302, a few are coming forward to dispute its central claim: Namely, that the pilots followed the manufacturer's safety protocols and did everything in their power to right the plane, but were unable to counteract the automated MCAS system, which effectively doomed everybody on the flight.

Though the report acknowledged that the pilots abandoned the safety procedures after they failed to wrest power back from MCAS, Roger Cox, a former accident investigator at the National Transportation Safety Board, who has flown earlier models of the 737, said the two pilots made one critical oversight: They left the engines set to maximum thrust, Bloomberg reports.

All of the pilots interviewed by BBG agreed that the failure to pull back on the throttle was critical, and eventually made it impossible for the pilots to pull the plane's nose back up manually.


The plane took off at 94 percent of full power, according to the report. That is normal for liftoff, but pilots then typically pull back the power soon afterward. Even though the captain called for setting the speed at 238 knots, or 274 miles per hour, about a minute after takeoff, the engine thrust remained at the same level for the entire short flight, according to the report.

Before it picked up speed in its final dive, the plane was flying as fast as 365 knots, or 420 miles an hour - almost twice the usual top speed at that low altitude. In addition to the multiple warnings prompted by the MCAS failure, the pilots were also getting audible alerts indicating they had exceeded the safe flying speed, according to the report.

Extremely high aerodynamic forces due to overspeed likely negated what slim chance they might have had to recover. Both sets of pilots seem to have been unaware of the extremely nose-down position of stabilizer trim in real time

 

[ArcadiaGP]

Text messages between Boeing employees in 2016 indicate that the company was aware of major problems with an automated feature on the 737 Max jet that made the aircraft difficult to control, the messages show.

https://www.washingtonpost.com/loca...b-ec56cd414732_story.html?cid=ed_npd_bn_tw_bn

 

[BigRed]

Full disclosure: I've not read the whole thread.

Just restating the equation in the op....

Misery = Being stuck on a plane with that piece of **** Andre' Carson.

 

[ATOMonkey]

Text messages between Boeing employees in 2016 indicate that the company was aware of major problems with an automated feature on the 737 Max jet that made the aircraft difficult to control, the messages show.

https://www.washingtonpost.com/loca...b-ec56cd414732_story.html?cid=ed_npd_bn_tw_bn

My takeaway... The FAA doesn't actually do anything useful. I'm sure the FDA is just as bad. In fact, I'm nearly certain of it.

 

[jspy5]

Full disclosure: I've not read the whole thread.

Just restating the equation in the op....

Misery = Being stuck on a plane with that piece of **** Andre' Carson.

You're being too kind concerning Andre'.....

 

[INgunowner]

My takeaway... The FAA doesn't actually do anything useful. I'm sure the FDA is just as bad. In fact, I'm nearly certain of it.

You can add the USDA to that list.
Remember kids, Trust but Verify.

 

[KLB]

It would be easier to list the ones that are useful.