Systems: Flight Controls Flashcards
What flight control surfaces are hydraulic?
The rudder and ailerons are mechanically actuated and hydraulically assisted. In case of loss of both hydraulic systems, the ailerons and rudder may still be mechanically actuated.
How can the elevator pitch be operated and where is this indicated?
Elevator pitch trim can be operated electronically by 2 split switches on each pilot’s control column. These switches, when moved , send a signal to the electronic motor to position the entire horizontal stabilizer, thereby reducing control column forces.
If the main channel fails, pitch trim can be operated on a backup channel by an additional split switch on the aft portion of the center pedestal. Indications of pitch trim position are in the EICAS and are represented by a numerical system and green band.
What does the elevator disconnect handle do?
Mechanically disconnects the left and right elevators from each other via the torque tube and allows the free elevator to resume pitch control. (One pilot will have pitch control.)
How are the ailerons, rudders, spoilers and speed brakes actuated?
Ailerons, rudder, spoilers and speed brakes are actuated hydraulically. In the event of a total hydraulic failure, ailerons and rudder are mechanically actuated. (Control forces will be much heavier with no hydraulic assistance.)
Can hydraulic assistance to the ailerons and rudder be shut off?
Yes, via 4 push buttons on the hydraulic section of the overhead panel. When pressed (released) the associated control actuator is disabled and hydraulic assistance is removed from that particular system.
What does the EICAS message RUDDER OVERBOOST mean and when would it be displayed?
The message means both rudder system hydraulic actuators are pressurized above 135 knots. Normally above 135 knots, a speed switch disables rudder system #1 to prevent rudder overboost.
What 3 conditions must occur to activate rudder hardcover protection?
Rudder deflected 5 degrees +- 1
Force above 130 lbs on the pedal to counteract rudder deflection
Both engines running above 56% N2
How are the flaps actuated?
By 2 electric flap motors. When the flap lever is moved, a signal is transmitted to the Flap Electronic Control Unit (FECU) to lower the flaps to the commanded setting.
What is the purpose of the flap velocity sensors?
They are responsible for monitoring the speed of the flap motors. In the event that flap panel asymmetry is detected, the flap system is disabled.
What conditions must be met for ground spoilers to open?
Airplane on the ground
Main landing gear wheel speed greater than 25 knots
Both engine thrust lever angles set to below 30 degrees or both engines N2 below 56%
Ground spoilers open automatically with no pilot action when all 3 conditions are met.
What conditions must be met for the speed brakes to open?
Speed brake lever set to open
Thrust lever angle of both engines set to below 50 degrees
Flaps at 0 or 9 degrees
I’d speed brake lever is commanded open and any of the above criteria are not met, the speed brake panels are kept closed and a caution message (SPBK LVR DISAGREE) is generated on the EICAS.
Under what conditions is the stick pusher inhibited?
On the ground (except during SPS test)
Below 0.5 gs
If the quick disconnect button is pressed
Below 200 ft AGL (if RA is failed, reverts to 10 seconds after takeoff)
If any SPS cutout buttons are released
Above 200 KIAS
If one SPS channel is inop
What are the travel limits of the rudder?
+-15 degrees on the ground and in flight
How many rudder actuators are there?
The rudder PCU is a dual hydraulic unit, simultaneously powered by both hydraulic systems. Each PCU hydraulic circuit controls the hydraulic power to one respective rudder actuator. Because of this, the rudder system is divided into rudder system 1 and rudder system 2.
What would happen to the rudder if the hydraulic system lost power?
Both rudder systems would lose hydraulic assistance and the rudder would operate purely mechanically.
