few pictures from my day job

adreamer

Well-Known Member
Enjoy these few pictures.

First one, Delta's MD-80 or 90 while holding short of runway 13 at LGA.

Second, Charlotte Douglas Intl. Approach from NE(runway 23)

Third, I think it was KIAD - Washington Dulles. can't remember.

BTW, if some MD drivers would care to explain why one elevator is up in comparsion to another. It would be great. :)
 

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ERfly

Well-Known Member
BTW, if some MD drivers would care to explain why one elevator is up in comparsion to another. It would be great. :)
Not an MD-80 driver, but I think I know this one. The elevator on the MD-80 (and ailerons) are not hydraulic. They use control tabs, so until they have an air load on them, they just flutter around freely in the breeze. Correct me if I'm wrong.
 

JoelT

Well-Known Member
Not an MD-80 driver, but I think I know this one. The elevator on the MD-80 (and ailerons) are not hydraulic. They use control tabs, so until they have an air load on them, they just flutter around freely in the breeze. Correct me if I'm wrong.
Correct, the DC-9 and all of its variants (MD-80, 82, 83, 84, 88, 90, 717) do not have hydraulic flight controls (except for the rudder). They use "control tabs" to move the surfaces aerodynamically. When doing the walk around you can move the aileron up and down but, the yoke in the cockpit will not move. However, if you move the tab the yoke will move.
 

Matt13C

Well-Known Member
Not an MD-80 driver, but I think I know this one. The elevator on the MD-80 (and ailerons) are not hydraulic. They use control tabs, so until they have an air load on them, they just flutter around freely in the breeze. Correct me if I'm wrong.
So when you pull the yoke back you are not actually pulling the elevator but just a control tab attached to the elevator? Was this a way to make the controls feel lighter without using hydrilics?
 

skidz

Well-Known Member
That's interesting. I never thought that the airplane of that size wouldn't have hydraulics. Does that make the airplane real hard to control? How do those tabs really work? Are there some other sorts of actuators involved or it's just certain way pullies are set up?
 

Derg

New Arizona, Il Duce/Warlord
Staff member
So when you pull the yoke back you are not actually pulling the elevator but just a control tab attached to the elevator?
Correct. The control tab is used to "fly" the surface to where it needs to be.

Was this a way to make the controls feel lighter without using hydrilics?
No idea. They're 'heavy' on the controls for sure.

Just a minor correction, the MD-90 had hydraulically-augmented pitch control. To me, it feels a lot like a 757.
 

citabriapilot

Well-Known Member
It also has an hydraulic elevator augmentation device engineered in there. I see a lot of captains push full forward on the yoke as we pour on the coals. They say it's to make sure both sides of the elevator are equal.

We do it on the control check prior to taxi, so I don't know what difference it makes to do it again, though.
 
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