"Paul Austin"

wrote:Something I saw raised a question in my mind: An MD-80's T-tail had
one half pitched up and the other half pitched about neutral.

This is a situation that is specific to the DC-9/MD-80 series airplanes. These
aircraft have elevators that are not connected to the control yoke in the
cockpit. Rather, the yoke drives the trailing edge tabs only, and thus the
elevators follow the "trim force" from the trailing edge tabs. Pitch trim, in
the usual sense, is attained by a trimable horizontal stabilizer. During
pretakeoff checks, the pilots will push forward on the control yoke to activate
the "stall recovery" (for lack of a better word at this moment) actuator; this
actuator will force the elevators down in unison, to produce a nose down
control input should a "stall recovery" be commanded by the aircrew. Just prior
to takeoff, the elevators appear in "harmony" to be connected together.

Therefore, seeing a split elevator on DC-9/MD-80 aircraft, while on the ground,
is normal, though visually disconcerting.

VL