737 max

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Raymond Hall
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Re: 737 max

Post by Raymond Hall » Fri Apr 05, 2019 11:07 am

yycflyguy wrote:
Fri Apr 05, 2019 8:11 am
The AoA never had, and still does not have a comparator function. That's why these planes crashed.
If that is the case, why did the A.D. of November 7th require adding the line "AOA Disagree (If Option is Installed)" to the manual?
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yycflyguy
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Re: 737 max

Post by yycflyguy » Fri Apr 05, 2019 12:15 pm

Raymond Hall wrote:
Fri Apr 05, 2019 11:07 am
yycflyguy wrote:
Fri Apr 05, 2019 8:11 am
The AoA never had, and still does not have a comparator function. That's why these planes crashed.
If that is the case, why did the A.D. of November 7th require adding the line "AOA Disagree (If Option is Installed)" to the manual?
I'll try to clarify; I was referring to the fact that there is no electronic comparison of AoA information before MCAS activation. Just one erroneous air data sensing out of two would activate the MCAS trimming - also with no indications to the pilot other than the trim wheel spinning forward. The AoA Disagree annunciation now appears on the PFD (not prominently) but it does not inhibit MCAS from trimming. The "software patch" was supposed to address that.
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Re: 737 max

Post by Raymond Hall » Fri Apr 05, 2019 1:20 pm

yycflyguy wrote:
Fri Apr 05, 2019 12:15 pm
I'll try to clarify; I was referring to the fact that there is no electronic comparison of AoA information before MCAS activation. Just one erroneous air data sensing out of two would activate the MCAS trimming - also with no indications to the pilot other than the trim wheel spinning forward. The AoA Disagree annunciation now appears on the PFD (not prominently) but it does not inhibit MCAS from trimming. The "software patch" was supposed to address that.
Therein lies the rub. There is a comparator function, but it does not (as yet) stop the MCAS from engaging. So difficult decisions must be made. If the warning is valid (i.e. the aircraft is approaching a stall), immediate intervention is required. Hence, MCAS activation. But if the warning is false, MCAS activation leads to a miserable almost immediate consequence.

Boeing is capable of much better than letting aircraft operate without managing the resolution of that information conflict. As late as one day prior to the USA grounding of the aircraft, Boeing's public position was that the aircraft were still safe by reason of the AOM's existing procedures, that the pilots were expected to know and to implement.

The reality, in practice, was much different. 40 degrees pitch down. Airspeed over 500 kts on impact, and the F/O unable to overcome the forces in the trim wheel (in a timely manner) to avert the CFIT. The jackscrew was found to be in the full nose down position on impact.

Houston. We have a problem. And that problem is in the flawed design of the system, among other factors.
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florch
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Re: 737 max

Post by florch » Fri Apr 05, 2019 1:28 pm

LOC-I not CFIT. UFIT maybe.
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aV1aTOr
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Re: 737 max

Post by aV1aTOr » Fri Apr 05, 2019 3:51 pm

By definition these events were the furthest thing from CFIT possible.
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The Hammer
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Re: 737 max

Post by The Hammer » Fri Apr 05, 2019 6:29 pm

Even a cheaply made Metro 23 needs both AOA systems to agree before the pusher comes on. You only get the Stall warning (audible and annuniciator on glareshield) if they don't agree.

Pretty odd decision by Boeing.
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Re: 737 max

Post by corethatthermal » Fri Apr 05, 2019 7:12 pm

perhaps 1 fix would be to attach a string to the mcas cb and affix to the pilots teeth . pilot pulls hard on the yoke, body moves fwd, mcas disconnects problem over,,,,, just sayin,,
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Re: 737 max

Post by fruitloops » Sun Apr 07, 2019 7:25 pm

2 INITIAL FINDINGS
On the basis of the initial information gathered during the course of the investigation, the following
facts have been determined:
 The Aircraft possessed a valid certificate of airworthiness;
 The crew obtained the license and qualifications to conduct the flight;
 The takeoff roll appeared normal, including normal values of left and right angle-of-attack
(AOA).
 Shortly after liftoff, the value of the left angle of attack sensor deviated from the right one
and reached 74.5 degrees while the right angle of attack sensor value was 15.3 degrees;
then after; the stick shaker activated and remained active until near the end of the flight.
 After autopilot engagement, there were small amplitude roll oscillations accompanied by
lateral acceleration, rudder oscillations and slight heading changes; these oscillations also
continued after the autopilot disengaged.
 After the autopilot disengaged, the DFDR recorded an automatic aircraft nose down (AND)
trim command four times without pilot’s input. As a result, three motions of the stabilizer
trim were recorded. The FDR data also indicated that the crew utilized the electric manual
trim to counter the automatic AND input.
 The crew performed runaway stabilizer checklist and put the stab trim cutout switch to
cutout position and confirmed that the manual trim operation was not working.
3 SAFETY ACTIONS TAKEN
The day of the accident, the operator decided to suspend operation of B737-8MAX.
On 14th March 2019, Ethiopian Civil Aviation Authority issued NOTAM regarding “The operation of
Boeing B737-8 ‘MAX’ and Boeing B737-9 ‘MAX’ aircraft from, into or over the Ethiopian airspace,
which is still active at the date of this report publication.
4 SAFETY RECOMMENDATIONS
 Since repetitive un-commanded aircraft nose down conditions are noticed in this
preliminary investigation, it is recommended that the aircraft flight control system related
to flight controllability shall be reviewed by the manufacturer.
 Aviation Authorities shall verify that the review of the aircraft flight control system related
to flight controllability has been adequately addressed by the manufacturer before the
release of the aircraft to operations.
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Re: 737 max

Post by fruitloops » Sun Apr 07, 2019 7:28 pm

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Re: 737 max

Post by HavaJava » Mon Apr 08, 2019 12:27 am

A couple quick questions for the airline pilots out there. I’m trying to get a general feeling for the experience/airmanship level of my colleagues around the world. For any transport category jet, how many of you would:

1. Engage an autopilot with a stick shaker active or any other signs of unreliable airspeed on departure?
2. Retract flaps with a stick shaker active or any other signs of unreliable airspeed on departure?
3. Be uncomfortable manually controlling thrust at any point during the flight.
4. Be uncomfortable manually flying the aircraft during an emergency?
5. Distrust the average pilot in your company to accurately fly manually during an emergency.
6. Not use the electric trim system to relieve control column pressure (if it is having a positive effect, such as was the case in the Lion-air and Ethiopian accidents)
7. Fly the #$&* airplane?!?
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Re: 737 max

Post by Daniel Cooper » Mon Apr 08, 2019 7:48 am

8. Sit in armchair
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Re: 737 max

Post by HavaJava » Mon Apr 08, 2019 8:07 am

I’ll keep doing 1-7 if you keep doing 8
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Re: 737 max

Post by goingnowherefast » Mon Apr 08, 2019 11:24 am

Depends. Are you worried about a flap overspeed on both ASIs? If so, I'm not too worried about the stall indications. Personally, I'd probably leave the configuration alone and fly just under the flap speed limit, but I don't have any experience on any model of 737, so not sure how appropriate or easy that is. I've also never flown a plane with MCAS activating inappropriately, so hard to say there too.

4 pilots are dead, who lost the fight for their lives. They used all their experience and training in that fight, and it was obviously not enough. Now the investigators are trying to figure out why.
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Re: 737 max

Post by pilotbzh » Mon Apr 08, 2019 12:04 pm

max speed for flap 1-5 is 250kts, no need to go faster if you going back to the Airport...
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Re: 737 max

Post by L39Guy » Mon Apr 08, 2019 10:35 pm

I have lurked on this forum for a long time but now it's time to weigh in on substantial issues like the MAX MCAS. To address HavaJava's previous question:
1. Engage an autopilot with a stick shaker active or any other signs of unreliable airspeed on departure?
the basic response for all Boeing aircraft is autopilot/autothrottles off, set an attitude and power setting to start getting things sorted out including identifying which of the three airspeed indicators are unreliable. I am not MAX qualified but I believe the attitude/power is with flaps out 10 degrees/80% and 4 degrees/75% clean. Note that in both fatal accidents (Lion Air 610 and Ethiopean 302 none of the pilots did the AIRSPEED UNRELIABLE memory checklist despite stall warnings starting upon lift-off). In the Ethiopean case, it would have been most helpful to manage the speed later as the engines were at 94% until impact thus producing super high speeds and high aerodynamic loads on the stabilizer.
2. Retract flaps with a stick shaker active or any other signs of unreliable airspeed on departure?
Once one has established which airspeed indicator is misbehaving, one could retract the flaps using the other two airspeed indicators to provide the flap retraction speed. Personally, I would be looking to land at the departure airport immediately unless runway length, weather, overweight aircraft, etc precluded a safe landing. In the Lion Air (previous day's flight) and the Ethiopean flight (initially at least) they were prepared to fly an hour or more in stick shaker to get to destination. Bad judgement in my opinion.
3. Be uncomfortable manually controlling thrust at any point during the flight.
I would hope not as that is a basic flying skill.
4. Be uncomfortable manually flying the aircraft during an emergency?
I would hope not as that is a basic flying skill.
5. Distrust the average pilot in your company to accurately fly manually during an emergency.
I have no concerns about Western pilots (Canadian, US, Mexican, Western European, Japanese). All of the rest, I would not based upon what others that have flown with them have told be about their basic flying skills. I believe that this issue will, in an honest evaluation of the Lion Air and Ethiopean accidents, prove to be a big issue.
6. Not use the electric trim system to relieve control column pressure (if it is having a positive effect, such as was the case in the Lion-air and Ethiopian accidents). Absolutely use the electric trim if it is working for you however the STAB TRIM RUNAWAY checklist says to turn off the electrical stab trim once you have the aircraft in trim and make further trimming with the wheel and crank.
7. Fly the #$&* airplane?!?
Aviate, navigate, communicate.
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Re: 737 max

Post by TeePeeCreeper » Tue Apr 09, 2019 9:28 pm

L39Guy wrote:
Mon Apr 08, 2019 10:35 pm
I have lurked on this forum for a long time but now it's time to weigh in on substance.

5. Distrust the average pilot in your company to accurately fly manually during an emergency.
I have no concerns about Western pilots (Canadian, US, Mexican, Western European, Japanese).
I quote you as an absolute idiot. Ethiopian Airways is one of if not the oldest African air operator’s. I have many friends that fly for them and have flown with them on that exact route as a PAX.

Your viterol isn’t welcomed. How dare you not insinuate but flat out say that one’s nationality should govern pilot proficiency? Really? Evidently you haven’t been around the ‘patch often.

This ain’t’ a “two bit airline” bru!
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Last edited by TeePeeCreeper on Tue Apr 09, 2019 9:40 pm, edited 2 times in total.

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Re: 737 max

Post by TeePeeCreeper » Tue Apr 09, 2019 9:30 pm

Double post. Sorry.
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Re: 737 max

Post by TeePeeCreeper » Tue Apr 09, 2019 9:37 pm

.
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Re: 737 max

Post by L39Guy » Wed Apr 10, 2019 10:49 am

First of all, let's cut the name calling and debate this like mature adults.

Let's take a look at the safety record of western airlines flying jet aircraft versus non-western airlines. We will deal with fatal accidents first then take a look at some non-fatal examples. The last fatal accident in Canada was First Air B737 in Resolute Bay in 2011 (https://en.wikipedia.org/wiki/First_Air_Flight_6560) and prior to Air Ontario in Dryden in 1989 (https://en.wikipedia.org/wiki/Air_Ontario_Flight_1363). Two fatal accidents in 30 years. Pretty good record I would say.

In the US, I have read, but have not verified, that there has been a single fatality in the past 10 years, the poor lady that got sucked out the window of a Southwest B737 after the left engine came apart and a piece of shrapnel broke the window beside her. 1 fatality in 10 years. Damn good record I would say.

Let's look at British Airways, Lufthansa, JAL, ANA, Singapore Airlines, Cathay (the last two having strong British regulatory influence), KLM, Alitalia. I cannot think of a fatal accident with those air carriers in the past 10 to 20 years but I stand to be corrected. Air France has been a relative disaster (the Rio flight (https://en.wikipedia.org/wiki/Air_France_Flight_447), Toronto going off the end (not fatal by pure luck)).

As you contemplate the absolute number of fatal accidents, consider too the number of aircraft. In Canada there is AC, WJ, Sunwings, Cdn North, Transat, etc. I am not going to do the math but I would submit that it is in the order of about 500 jet aircraft.

In the US, Southwest alone has 750 B737's, United 768 jet aircraft, American 960 jet aircraft, 886 jet aircraft. And I am not including JetBlue and the others. Over in Europe, BA has 274 aircraft, KLM 120, Lufthansa 310, etc.

I hope that you are getting the picture that all of these western airlines have large fleets (hence lots of flying) but few fatal accidents in absolute terms (raw numbers) and relative terms (losses per million hours).

Now, let’s look at the safety record of the two accident airlines with the MAX. Lion Air has 117 aircraft and have had one fatal accident in the past year. Go to avherald.com and see how many accidents they have which, by the grace of God, were not fatal. Runway overruns like crazy, landing in the sea short of the runway (http://avherald.com/h?article=460aeabb/0007&opt=256). I would submit that their safety record is appalling on an absolute and relative basis.

Ethiopian Airlines has 82 jet aircraft. In the past nine years they have had two fatal accidents – the infamous, recent MAX accident as well as stalling a B737-800 and crashing while departing Beirut (https://en.wikipedia.org/wiki/Ethiopian ... Flight_409). That is not a good safety record in absolute or relative terms either.

The question now becomes, what is it that separate the western carriers with stellar safety records from the others (largely non-western) that do not? It can’t be the aircraft as they all flying the same aircraft. It can’t be the fuel as they all use the same fuel. The only other thing that I can think of is the human aspect, maintenance and operations.

Before I discuss this, I want to be clear: my criticisms are of not only the individuals involved but more so the airlines that employ and train them as well as the local Civil Aviation Authority (CAA) that oversees all of them. They are all culpable.

Let take a look at the Lion Air MAX incident and accident. From a maintenance perspective, it appears that the AOA vane was written up and replaced between the two flights and was ground checked serviceable.

The first incident flight with that aircraft, Lion Air 043, the aircraft immediately displayed airspeed unreliable characteristics, the crew correctly handled this, accelerated to flap retraction speed and once the flaps were up the MCAS failure (identical to the stab trim runaway) manifested itself (source preliminary accident report). The crew eventually got the stab trim runaway under control and continued to destination with unreliable airspeed and the stick shaker activated the entire time – I would consider that to be a questionable decision.

It is interesting to note too that it was a jumps eater from another airline that had to tell the operating crew to turn off the stab trim cut-off switches. A stab trim runaway is a memory drill.

The same aircraft the next day (Lion Air 610) had the same thing only this time the crew did not do the airspeed unreliable checklist nor did they have the assistance of a jump seater to tell them to turn off the stab trim cut-off switches. The Captain fought with the airplane then handed control to the FO while the Captain went looking through the NNC for something that would address the stab trim runaway, the memory drill. The FO lost control of the aircraft and the rest is history.

With respect to these two Lion Air flights, I have the following questions/criticisms from a training, airmanship, and experience perspective:

How can B737 type endorsed pilots not be able to recognize airspeed unreliable and stab trim runway and not perform the memory drill? These are simple emergencies. Indeed, not doing the airspeed unreliable checklist and not getting the power back from take-off to 85% made life difficult later as the aircraft was flying around at 340 kts. and trying to manually trim is about four times harder than at 200 kts or less.

Why did the first Lion Air flight choose to fly to destination? It is interesting to note that the investigation is hanging their hat on the NNC checklist not explicitly stating “Land at the nearest suitable airport” as justification for flying an hour and half with manual trim, unreliable airspeed and stick shaker.

The fatal accident flight actually selected Flaps 5 after the stab trim runaway – this stopped the runaway (as MCAS is designed to do). So rather than keep flaps 5 and land (or perhaps eventually go to landing flap and return to land), they chose to clean up the aircraft and sure enough the stab trim runway reared its ugly head and ultimately caused the accident. This again, is a highly questionable action. Why screw with it once you get the problem solved. Get your ass on the ground and sort it out.

Now, onto Ethiopian. Every B737 pilot in the planet either knew or ought to have known about MCAS and the associated issues following the issuance of the emergency airworthiness directive in November.

The Ethiopian aircraft exhibited the same airspeed unreliable upon lift-off (stick shaker, etc.) yet the memory drill was not done. And, like the Lion Air accident, getting the power back from take-off to the prescribed value would have managed the speed.

Of course, once the flaps went up the MCAS misbehaved yet the stab trim runaway, a memory drill but also something that was emphasized with the AD, was not done.

My criticisms of the Ethiopian flight are similar to that of Lion Air. Why did two B737 endorsed pilots not do the memory drills for unreliable airspeed first (in fact it was done incorrectly as the Captain tried to engage the autopilot where the drill is to disengage autopilot and auto throttle) then stab trim runaway.

My other issue in the Ethiopian accident is the experience of the FO – 351 hours of total time, of which 207 was B737 time (likely largely flown on the autopilot) leaving only 154 hours of flying time? Really? This guy and the Captain were placed in an impossible situation to deal with these two issues and I fault the airline and the regulator for this.

In conclusion, take a look at where the accidents are happening and who is involved. And I haven’t even dealt with the turbo-props such as shutting down the wrong engine in Taipei, the 777 in SFO, the 777 in Dubai the last two of which are examples of perfectly servicable aircraft crashing and only through the survivability of the 777 that no one was killed from the impact.
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Re: 737 max

Post by corethatthermal » Wed Apr 10, 2019 7:51 pm

After operating the stab cut-out switches, the crew were getting things under control EXCEPT for 1 glaring and obvious error, the throttles were still at 94% and the A/C was overspeeding,,,, at that time, I would suggest that they should have remembered to FLY the A/C ( pitch+ power = Airspeed ) But they failed. Both Boeing and the crew were at fault. To add insult to injury, they turned the known problem back on ( trim switches )
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Re: 737 max

Post by pilotbzh » Thu Apr 11, 2019 5:16 am

Ethiopian Crash Data Analysis Points To Vane Detachment
Guy Norris | Aviation Week & Space Technology
Apr 10, 2019

LOS ANGELES—As the investigation continues into the causes of the Mar. 10 Ethiopian Airlines Boeing 737 MAX accident, sources close to the probe say flight data recorder (FDR) data firmly supports the supposition that the aircraft’s left angle-of-attack (AOA) sensor vane detached seconds after take-off and that, contrary to statements from the airline, suggests the crew did not follow all the steps for the correct procedure for a runaway stabilizer.

Detailed analysis of the FDR trace data shows that approximately six seconds after liftoff was signaled by the weight-on-wheels switch data, the data indicate the divergence in angle-of-attack (AOA) and the onset of the captain’s stick-shaker, or stall warning. Almost simultaneously, data shows the AOA sensor vane pivoted to an extreme nose-high position.

This, says one source, is a clear indication that the AOA’s external vane was sheared off—most likely by a bird impact. The vane is counter-balanced by a weight located inside the AOA sensor mounting unit, and without aerodynamic forces acting on the vane, the counterweight drops down. The AOA sensor, however, interpreted the position of the alpha vane balance as being at an extreme nose-high angle-of-attack.

With the stick shaker active, the trace indicates the crew pushed forward on the column to counteract what they believed were indications of potential approach to stall. The aircraft, now in level flight, also accelerated rapidly as its power setting remained at 94% N1 thrust used for take-off. This was followed by some manual trim inputs using the thumb switches on the control column.

Seconds after speed advisories were heard, the crew raised the flaps. With the autopilot turned off, flaps up and erroneous AOA data being fed to the flight control computer (FCC), the stage was set for the MAX’s maneuvering characteristics augmentation system (MCAS) to activate. This is indicated by approximately 8-sec of nose-down stabilizer movement, which was followed by the use of manual trim on the control column. However, with the MCAS having moved the stabilizer trim by 2.5 units, the amount of manual nose-up trim applied to counteract the movement was around 0.5 units, or roughly only 20% of the amount required to correctly re-trim the aircraft.

Because of the way the aircraft’s flight control computer P11.1 software worked, the use of manual trim also reset the MCAS timer, and 5 sec. later, its logic having not sensed any correction to an appropriate AOA, the MCAS activated again. The second input was enough to put in the full nose-down trim amount. The crew again manually counteracted with nose-up trim, this time offsetting the full amount of mis-trim applied by the latest MCAS activation.

By then, some 80% of the initial MCAS-applied nose down trim was still in place, leaving the aircraft incorrectly trimmed. The crew then activated the stabilizer trim cutoff switches, a fact the flight data recorder indicates by showing that, despite the MCAS issuing a further command, there was no corresponding stabilizer motion. The aircraft was flying at about 2,000 ft. above ground level, and climbing.

The crew apparently attempted to manually trim the aircraft, using the center-console mounted control trim wheels, but could not. The cut-out switches were then turned back on, and manual trim briefly applied twice in quick succession. This reset the MCAS and resulted in the triggering of a third nose-down trim activation lasting around 6 sec.
The source says the residual forces from the mis-trim would be locked into the control system when the stabilizer cut-off switches were thrown. This would have resulted in column forces of up to around 50 lb. when the system was switched back on.

Although this could have been reduced by manually trimming the aircraft, this did not occur, and the third MCAS activation placed the aircraft in a steep nose-down attitude. This occurred with the aircraft near its peak altitude on the flight—about 6,000 ft. The engines remained at full take-off power throughout the flight, imposing high aerodynamic loads on the elevators as the crew attempted to pull back on the columns.

Vertical acceleration data also indicates momentary negative g during which the AOA sensor on the left side unwinds. This is seen as further validation of the theory that the external part of the alpha vane was detached as the apparent change in angle indication could only be explained by the effect of negative g on the counterbalance weight, forcing it to float up inside the sensor housing. In addition, the captain’s stick shaker also comes off twice in this final phase, further reinforcing the severed vane notion.

The source indicates the crew appeared to be overwhelmed and, in a high workload environment, may not have followed the recommended procedures for re-trimming. Boeing’s stabilizer runaway checklist’s second step directs pilots to “control aircraft pitch attitude manually with control column and main electric trim as needed,” according to one U.S. airline’s manual reviewed by Aviation Week. If the runaway condition persists, the cut-out switches should be toggled, the checklist says.
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Re: 737 max

Post by tallyho » Thu Apr 11, 2019 9:05 am

Anyone have any insight as to why the crew having activated the stabilizer trim cut out switches were then unable to manually trim the aircraft using the trim wheel? Isn't that the whole point of the manual trim wheel?
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Re: 737 max

Post by telex » Thu Apr 11, 2019 9:10 am

tallyho wrote:
Thu Apr 11, 2019 9:05 am
Anyone have any insight as to why the crew having activated the stabilizer trim cut out switches were then unable to manually trim the aircraft using the trim wheel? Isn't that the whole point of the manual trim wheel?
Lifted from another source...

Reference Boeing 737 Classics and NG FCTM under the chapter Non-Normal Operations/Flight Controls and sub heading Manual Stabilizer trim.

Edited for brevity one paragraph states: "Excessive air loads on the stabilizer may require effort by both pilots to correct mis-trim. In extreme cases it may be necessary to aerodynamically relieve the air loads to allow manual trimming. Accelerate or decelerate towards the in-trim speed while attempting to trim manually."

What control movements are needed to "aerodynamically" relieve the airload? This is not amplified in the FCTM and from experience I believe few pilots know what Boeing mean by "aerodynamically relieve the airload".
In fact I wouldn't be surprised in the two recent Boeing 737 MAXI accidents and the apparent inability for their crews to recover from unusual attitudes (nose down) could be traced in part to absence of knowledge on how to aerodynamically relieve airloads if using manual stabilizer trim.

My understanding of the meaning of "aerodynamically relieving" is best illustrated as follows: An aircraft suffers a severe nose down runaway stabilizer trim.causing the aircraft to initially dive and rapidly lose height. Any delay caused by surprise factor further compromises flight path control. Both pilots haul back hard on the elevators while attempting back trim using manual stabilizer trim. Due to increasingly heavy aerodynamic airloads against the stabilizer the effort to manually rotate the trim wheels in this condition is considerably higher than normal.

To relieve these airloads so that manual stabilizer trim can be used to wind off the forward position of the stabilizer which has caused the problem in the first place, it may be necessary for the crew to first attempt to raise the nose well above the horizon. With the nose high, the control column is immediately released from all back pressure. This action momentarily "aerodynamically relieves the airloads that in turn allows rapid unimpeded manual operation of the stabilizer trim control; to return the stabilizer to mid-range and thus permit more effective elevator effectiveness.

This "yo-yo" technique may be the only effective way of overcoming the difficulty of using the manual stabilizer trim during an attempted recovery from a high speed dive where electrical operation of the stabilizer is unavailable. To my knowledge this technique is not covered during simulator training for manual stabilizer trim operation
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Re: 737 max

Post by L39Guy » Thu Apr 11, 2019 12:29 pm

What they mean by "aerodynamically relieving air loads" is to move the nose of the aircraft in the direction opposite to the over trim and manually trim at the same time (by the other pilot) using the manual trim wheel (not the trim tab switches on the control column). Think of reeling in a fish with a fishing rod.

For example, in a nose down over trim, pull up the nose then lightly check forward and have the other pilot manually crank the wheel pulling in the excessive nose down trim. All the better if you have some altitude to play with to allow the speed to change to get closer to the in trim speed.
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Re: 737 max

Post by Gino Under » Thu Apr 11, 2019 2:13 pm

"Excessive air loads on the stabilizer may require effort by both pilots to correct mis-trim.” No kidding?

Effort. WTF does that mean? Physical effort. And, at what point do you reach an excessive air load.
Wouldn’t it be nice if Boeing (and all the other OEMs for that matter) who publish these manuals gave us a f**kin’ hint as to what more accurately they mean when they write stuff like this? I thought they wrote this stuff as guidance.

Do they mean physical effort on the controls? Most likely.

Oh? But that might mean different things across the world’s population of pilots flying this particular model of Boeing.
A range of “effort” expressed in kilos or pounds might help.

I remember decades ago my Airbus FCOM informed me I could disconnect the autopilot with 20 decaNewtons of pressure.
Great! What’s a decaNewton? They eventually published the value in pounds and kilos so your average pilot without an engineering degree could put 1 and 1 together.

:partyman:
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