Elevator tabs

[killairbus 3]

When I load up my 737 and pushed back, I did a flight controls test while looking from the outside and the tabs on the elevator are moving in the same direction as the elevator. After I landed an hour later, the tabs were then moving in the opposite direction. 

Edit: The reversal happens when flaps are deployed. 

Is this normal?

-Angelo Busato

Edited September 15, 2018 by killairbus

[MarkJHarris 128]

Yes!

[killairbus 3]

16 minutes ago, MarkJHarris said:

Yes!

So why do the tabs move in the same direction as the elevators when flaps are deployed?

-Angelo Busato

[MarkJHarris 128]

Just looking it up on the FCOM. back in a mo...

[MarkJHarris 128]

When the flaps are up, the elevator tab is working like a balance tab.
When the flaps are not up, the elevator tab is working as a anti−balance tab due to a hydraulic actuator at the elevator tab control mechanism.
In manual reversion there is no hydraulic present at the actuator and the tab works as a balance tab regardless of the flap position.

 

[killairbus 3]

17 hours ago, MarkJHarris said:

When the flaps are up, the elevator tab is working like a balance tab.
When the flaps are not up, the elevator tab is working as a anti−balance tab due to a hydraulic actuator at the elevator tab control mechanism.
In manual reversion there is no hydraulic present at the actuator and the tab works as a balance tab regardless of the flap position.

 

Thanks for digging it up for me, under what section in the manual does it say that?

-Angelo Busato

[MarkJHarris 128]

Google actually. I know it does this, but our manuals don't mention it at all! I'm trying to get my CBT disc to work again but having difficulty.

This is actually a good example of the way Boeing (and Airbus) really don't want the pilots to know too much about their aircraft. If you really want to find out how it works you've got to do independent research. Sad, isn't it. The Approved Type Rating syllabus is very narrow and all CBT based.  Very different to my previous type ratings where you sat in a class room with an Engineer instructor at the front. You finished with a far better understanding of the systems and structure. 

Edited September 16, 2018 by MarkJHarris

[30K 72]

On 9/16/2018 at 8:06 PM, MarkJHarris said:

This is actually a good example of the way Boeing (and Airbus) really don't want the pilots to know too much about their aircraft.

Here in Germany, many airlines do not want the Pilots to be "distracted".

Example:

A friend of mine is a Cat b2 engineer and applied as a pilot. He never got a job because the airlines simply don't want a tech guy in the front, due to various reasons but one of them is that, when you get a warning light or something, you should not initially think:

Is it the socket? a short in the lamp? A condition in a secondary system? A broken cable? No, they want you to act immediately.

It seems harsh at the first thought but actually, if you spend 3 years at the minimum, thinking this way it's hard to simply turn that off.

Now you can discuss if this rule applies to non-tec people but I think it is definitely a good point.

Edited September 19, 2018 by 30K

[TopGun33 124]

8 hours ago, 30K said:

A friend of mine is a Cat b2 engineer and applied as a pilot. He never got a job because the airlines simply don't want a tech guy in the front, due to various reasons but one of them is that, when you get a warning light or something, you should not initially think.

Funny, that's exactly the reason why my best friend was hired at Ryanair as a pilot 7 years ago (he switched to another airline after that). He was a licence engineer and pilot, and they saw it as an added value.

[downscc 1,327]

8 hours ago, TopGun33 said:

Funny, that's exactly the reason why my best friend was hired at Ryanair as a pilot 7 years ago (he switched to another airline after that). He was a licence engineer and pilot, and they saw it as an added value.

I agree with that, and I'm not sharing the expressed sentiment that Boeing or operators prefer non-technically trained pilots.  Aviation has advanced since WWII and the days of the Pan Am Sky Gods and has become a very technical field.  The basic curiosity to understand not only how something works but why is a very positive attribute and is very sought after in the military, as well as I presume it is in the industry.

Reminds me of a time I was copilot ferrying a newly overhauled C414A with an ATP employed with an airline in the left seat.  I watched him closely to see what knowledge could be gained from this very well trained pilot.  Enroute about 16500 over Houston, in contact of course with them, all electrics suddenly went dark.  No radios, no navs, nada.  I thought great, lets see how he handles this. He knew his lost comm procedure but we were VFR using ATC for advisories over a busy chunk of airspace.  Well, turned out I was the only electrical engineer on board and I had a pretty good idea of the problem.  Before I picked up the aircraft it had to be put on a battery charger to get her started.  I know that one alternator's field winding would take less current than two so I told him to turn off one of the two alternators and just like that all electrical was restored and we heard approach asking other aircraft in area to contact us.... comm reestablished and rest of trip uneventful.  Aircraft got a new battery very quickly.  I just don't buy the idea that an airline doesn't want pilots who are technically trained.

[MarkJHarris 128]

I don't think it's the airlines really. Airbus and Boeing control the data to their aircraft, and thus have control over the Simulators and ultimately the simulator training programmes.You have crews from all over the world, with various levels of experience being trained on a syllabus designed for the lowest common denominator., or most stupid pilot to be precise.

$ is the bottom line. so they train to the minimum standard. Some airlines recruiters might be technically weak and don't want to be shown up I guess.

Me? I like to know everything I can.

[Stearmandriver 2,225]

We're getting into a human factors / operational philosophy area now.  I don't think it's that airlines don't want technically proficient pilots. I certainly don't think it's a matter of pilot interviewers feeling threatened. (At least I don't think those things apply at U. S  airlines, I can't comment on culture elsewhere).

It's a matter of shifting from a mentality of creating technical experts to a mentality of creating airmen.  There are likely millions of technical details that are literally irrelevant to a pilot; this behavior change of the elevator tabs is a good example. I knew it happened, but I can't tell you where I picked that up, I don't know if it's in our company systems handbook or not.  But it's the kind of thing that you may as well omit for brevity, because there is literally nothing a pilot could ever do to affect it.  The elevator responsiveness will be what it'll be with the flaps up or down, manual reversion or hydraulics on, and there's nothing to be done about it. 

Better to focus a training syllabus on big - picture items, and only a level of technical knowledge that is actually applicable to operating airplanes.  Remember, in an abnormal situation, we really do not want pilots attempting their own technical troubleshooting.  The most technically - knowledgeable pilots in the world will still be nowhere near the level of career engineers and test pilots who, over months of testing and team collaboration, wrote the abnormal checklists.

Several accidents have resulted from pilots (usually in collaboration with mx folks on the ground) attempting to troubleshoot a problem in flight, and subsequently turning a manageable problem into an unflyable one.  

Point is, training philosophy has changed over the decades from being all about technical minutia to more of a human factors / event management philosophy, with a corresponding increase in safety.  Technical knowledge is certainly good, and more is better, but not to the detriment of these other aspects of training.  The simple fact is, pilots aren't engineers and they don't need to be, so training them to that level is a waste of time and resources.