When in the closed position, they fit flush with fuselage skin. An elevator speed brake interconnect provides a connection between the left-hand speed brake and the aircraft nose down elevator control cable. When the speed brakes open, the cable pulls and provides a nose down action to counteract the tendency of the aircraft to assume a nose up condition. When operating the switch to open the speed Figure 9-40. Speed brake control system.
Pressure is sent to the actuating cylinders, extending the speed brakes.
To close, the opposite solenoid energizes, repositioning the control valve and directing pressure to the retract side of the actuating cylinders, closing the speed brakes. When you depress or pull the manual override handle to operate the speed brakes, a plunger manually positions the control valve to direct pressure to the actuating cylinders. The spring bungee connected to the manual control lever returns the manual override handle assembly to the neutral position when the handle is released. If electrical power is applied while the manual override handle is actuated, the system will remain in the position selected by the handle. If the handle is released, the system actuates to the position selected by the control switch on the throttle lever.