Aircraft Control Systems Overview

To reduce any roll rate not commanded by the pilot.

It deactivates after five seconds and remains off for the duration of the flight.

The amount of roll spoiler deflection varies, with higher flap positions and airspeeds resulting in smaller spoiler deflections.

To damp dutch roll oscillations using sensor feedback and rudder pedal input.

It will be offloaded to the horizontal stabilizer.

Each pillow block consists of two ball bearings, an aluminum housing, and an externally-splined through-shaft that interfaces with the internally splined end fittings of the torque drive shafts.

The flap actuators perform three basic functions: 1) Conversion of high speed rotary motion at the input shaft to low speed linear motion at the translating nut, 2) Irreversibility (the translating nut cannot be back-driven in normal operation) and/or torque shaft or actuator disconnect system failure mode, and 3) System overload protection by limiting the maximum force that each actuator can apply.

The force-limiting function in each flap actuator provides overload protection of the flight control system components and supporting structure by limiting the maximum actuator output load. In the case of a flap actuator system (FAS) jam or any other condition that results in increased FAS loading, the force-limiting device stalls the actuator, causing a 'trip' in one of the system safety monitors, which then completely disengages the FAS.

The fly-by-wire technology in the flight control system ensures irreversibility of the flap actuators through a mechanism where the translating nut of the actuator cannot be back-driven in normal operation, even in the event of a torque shaft or actuator disconnect system failure.

The artificial feel mechanisms in the horizontal stabilizer system are designed to provide the pilot with appropriate feedback and control forces, simulating the natural feel of a conventional control system. These mechanisms help the pilot maintain proper control and situational awareness during flight.

The bungee rods act as a solid link between the wheel and column, allowing control in the event of a mechanical jam on the pilot or copilot side. They allow the control inputs from the pilots to be combined, preventing a jam on one side from completely overriding the other pilot's inputs.

In the event that both FCCs (all four channels) are inoperative, the Backup Flight Control Unit (BFCU) controls the elevators, ailerons, outboard spoilers (roll control only, no speed brakes), and rudder, allowing the aircraft to be safely flown.

The mechanical stops are used to limit the maximum displacement of the flight control surfaces, providing appropriate "feel" forces to the pilots and preventing the control surfaces from exceeding their design limits.

The pilot and copilot rudder pedals are mechanically connected with a hard link which cannot be overridden. This ensures that the rudder inputs from both pilots are combined, preventing a jam on one side from completely overriding the other pilot's inputs.

Trim switches are provided for the pitch, roll, and yaw axes, allowing the pilots to adjust the trim of the aircraft's control surfaces to maintain the desired flight attitude without constant input on the flight controls.

The aircraft hydraulic system provides pressurized fluid to position and control the flight control surfaces.

The REU can electrically hold a solenoid to keep the actuator in an active state, or it can remove power from the solenoid to force the actuator into a damped bypass operation.

In damped bypass mode, the actuator is in a passive condition that resists movement proportional to the rate at which the surface is moved, and hydraulic fluid is trapped within the actuator to prevent control surface flutter.

The EBHA has three modes of operation: Hydraulically Active, Electric Backup, and Damped Bypass. In the event that a surface cannot be powered by an engine-driven hydraulic source, the EBHA's Electrical Backup (EB) hydraulic pump will provide hydraulic pressure to operate the flight control surface.

Pilots may directly experience the behavior of damped bypass actuators by rotating an aileron surface upward or downward with the palms of their hands during preflight when hydraulic pressure is not available to either the left or right system.