ROLL CONTROL SYSTEM

Each aileron is powered by a tandem hydraulic actuator which normally allows each aileron to be powered by both hydraulic systems (Figure 1-15). Inputs to the actuators are made through independent, widely separated cable and linkage paths which connect through aileron tab shift mechanisms to the disconnect units. A single system of pushrods within the white area con-nects the disconnect units to the control stick.

If one hydraulic system is lost, the operative system will con-tinue to power both ailerons. Hence, the loss of one hydraulic system has no discernible effect on stick/surface response.

In the event one control path is lost, roll control will be provided by the connected aileron, and roll authority will be reduced by approximately one half. Normal stick force relative to roll rate will be experienced, but the stick will have to be moved twice as much for a given maneuver. If an aileron surface, aileron actua-tor, or a control path aft of the disconnectors becomes jammed, the aileron emergency disengage switch can be used to free the unjammed aileron. If a jam occurs with appreciable aileron de-flection, roll control in the opposite direction will be minimal;

e.g., if right aileron is jammed with an upward deflection, roll authority to the left will be reduced.

Artificial stick feel is provided by redundant devices located close to the aileron actuators. Trim is provided by two indepen-dent electrical circuits: the normal pitch/roll trim control circuit and the emergency override pitch/roll trim circuit. These circuits lead to a trim motor in each wing. The trim motor acts on the arti-ficial feel device, which in turn repositions the actuator to move the entire aileron surface. Sufficient trim for normal operations can be obtained from one trim motor. However, trim rate and authority will be reduced. Disengagement of an aileron will not cause loss of roll trim. No roll trim will be available in the man-ual reversion operating mode. (See section on MRFCS.) Aileron tabs are mounted on the inboard trailing edge of each aileron. During normal flight, the tabs are geared to reduce the aerodynamic loads on the ailerons, and are not directly con-trolled by lateral stick inputs. In manual reversion, lateral stick inputs are transmitted directly to the tabs, which in turn fly the ailerons.

A roll transducer attached to a crank in the forward fuselage provides input data to the IFFCC for PAC.

Figure 1-14. Pitch Control System Schematic

Elevator/Aileron Emergency Disengage Switches.

Two three-position lever-locked switches (Figure 1-17), plac-arded ELEVATOR EMER DISENGAGE and AILERON EMER DISENGAGE, are mounted on the emergency flight control panel. The switches are normally centered. In the event of a jam of a control path aft of the disconnector units, or a jam in the actuator or control surface, a light adjacent to the appro-priate switch will come on as abnormal stick force countering the jam is exerted. The stick is disconnected from the jammed side by moving the appropriate switch toward the light.

The stick becomes immediately free to control the unjammed control path. After disconnecting a jammed elevator, stick force will be momentarily higher than normal until the controllable elevator is displaced approximately 3° relative to the jammed surface, at which point the crossover shaft between the two ele-vator actuators will shear. The subsequent shearing of the eleva-tor crossover shaft will be accomplished with hydraulic powered inputs.

For both elevator and aileron control jams, normal stick force per g relative to roll or pitch input is experienced, but the stick has to be moved or trimmed approximately twice as much for a given maneuver. When a control path is not fully engaged at the disconnect unit, the ELEV DISENG or AIL DISENG light on the caution light panel comes on. When the switch is subse-quently moved to the center position or to disengage the opposite side, the surface will reconnect as soon as the stick is moved in alignment with the surface position. Though remotely possible, both elevators or ailerons can be disconnected, but one surface will automatically reconnect as soon as the stick is moved into alignment with the position of the control surface. The disen-gage circuits are powered by the DC essential bus.

Elevator/Aileron Disengaged Caution Lights.

The elevator and aileron disengaged caution lights (Figure 1-158), on the caution light panel, are placarded ELEV DIS-ENG and AIL DISDIS-ENG. The lights indicate that either or both elevator or aileron control paths are not connected at the disconnect units.

Elevator/Aileron Jam Indicator Lights.

The elevator and aileron jam indicator lights (Figure 1-17), on the emergency flight control panel, are placarded L ELEV/R ELEV, and L AIL/R AIL, respectively. These lights are con-trolled by load-sensing switches in the disconnector units and are powered from the auxiliary DC essential bus. In the event of an actual jam aft of the disconnect units, a light will come on to identify which side is jammed when 50 to 65 pounds of stick force against the jam is applied. The stick force must be maintained to keep the light on. The jam light will remain on for 3 to 5 seconds after the stick force required to turn the light

on is reduced. Stick force should be reduced during disengage-ment to relieve loads on the disconnect units and also to reduce transients as the disconnector actuates. The lights may come on when there is no jam condition by the application of stick force and rate in excess of the capacity of the powered actuators to respond. The lights may also come on during manual reversion because of the high stick force gradients.