Hi, I was wondering if you could raise the speed brake lever full aft during flight? Is this ok to do or the plane shake too much because of the drag? Or can you only raise the speed brakes 3/4 aft max and only full speed brake on the ground? Thank You :-)

November,The control logic will prevent the speedbrakes to deploy to full extension when the aircraft is airborne. The crew can select full speedbrakes, but the actual deployment will be limited. Full deployment is only available after wheel spin-up, e.g. on landing.Some aircraft types have a limitation on speedbrake and flap usage at the same time, the 747 is one of them. Teaches you good energy management. Most aircraft are prohibited from speedbrake usage when full flaps has been selected, but then again with full flaps there should be no need to extend speedbrakes unless you really screw things up.

However, there is nothing stopping you from pulling the speedbrake lever totally aft in flight.

"Full deployment is only available after wheel spin-up, e.g. on landing."Can't seem to find any reference to wheel spin-up in my 767, 747 and 747-400 engineering notes, Top Heavy.... The air-ground signal seems to be determined by gear truck tilt. For 767 Autospeedbrakes, there is also a gear hydraulic pressure sensing system, to prevent the Autospeedbrakes deploying in the air if the gear is not at the correct angle due to gear hydraulic failure.Is wheel spin-up mentioned in the 767 pilots' manuals?I'd imagine that the 737 or other jets smaller than the 767 might use a wheel spin-up system if there were no trucks to tilt(?). As a side note, I believe the 777 uses an air-ground system based on piezo-electric torsion sensors in the gear support beams.Cheers.Ian.

Ian,I defer to your technical knowledge of the 767. I am not rated on the machine, although we did use the 767-300ER when I completed application training many moons ago.The wheel spin-up thing is, I belive, something they tought us in Aerodynamics classes. But then again, the aircraft they used in those classes were the DC-9.Does seem a tad simpler than "piezo-electric torsion sensors" though :)