Flight Controls Flashcards
Draw the Flight Control System (Elevator, Ailerons, Stabilizer, Rudder, Slats/Flaps)
see study guide
What are the primary flight controls?
Ailerons, multifunction spoilers, elevator, rudder
What are the secondary flight controls?
Horizontal stab, multifunction spoilers when used as ground spoilers, slats/flaps, ground spoilers
The flight controls are moved via
Fly-by-wire FBW and conventional cables (aileron only)
How does the FBW system’s higher level functions work?
The FBW system incorporates higher level functions for safety and to reduce pilot workload. They get their commands from the FCM Flight Control Module. When higher level functions are not working, the controls are operating in Direct Mode.
Which controls have higher level functions? Which do not?
Elevator, multifunction spoilers, rudder, horizontal stab (not flaps, slats, ground spoilers, or ailerons)
What controls pitch?
Elevator, horizontal stab
Describe how the elevator works, draw the picture from the study guide
electrically controlled, hydraulically actuated; PCU Power Control Unit (a hydraulic actuator that replaces conventional control cables), ACE Actuator Control Electronic (the electronic unit controlling the PCU), and the FCM Flight Control Module (a computer inputting higher level functions)
What are the elevator higher level functions?
Gain on Airspeed (as airspeed increases, pitch deflection decreases), Elevator thrust compensation (pitch control is maintained during thrust changes), AOA limiting (essentially does not allow the aircraft to stall)
Describe how the horizontal stabilizer works, draw the picture from the study guide
electrically controlled, ELECTRICALLY actuated; HSA Horizontal Stabilizer Actuator (the electric motor that moves the horizontal stabilizer), ACE Actuator Control Electronic (the electronic unit controlling the HSA), FCM Flight Control Module (a computer interface for higher level functions
What are the higher level functions for the horizontal stab?
Configuration change compensation: Keeps the airplane trimmed via the autopilot and deployment of the speed brakes, prevents structural damage at high speeds
What is the trim priority?
Backup, captains, first officers, autopilot
What controls roll?
Ailerons and multifunction spoilers
Describe how the ailerons works, draw the picture from the study guide
mechanically controlled (No fly-by-wire), hydraulically actuated, PTU Power Control Unit (a hydraulic actuator controlled by conventional cables)
What high level functions are applied to the ailerons?
The aileron has no high-level functions
Describe how the multifunction spoilers work
5 panels per wing, the 3 outer panels are multifunction spoilers which (assist roll, are speed brakes, are ground spoilers), there are also 2 inner panels which are only used as ground spoilers
How is roll assist accomplished?
The 3 multifunction spoilers (3 outer panels) assist roll - in normal mode they are scheduled as a function of airspeed and flap setting - in direct mode, fixed gain applied independent of airspeed and flap setting
What are the speed brakes? How do they work?
The 3 outer panels (multifunction spoilers), when the handle is in the open position, the speed brakes will auto close if: slat/flap selection is 2 or greater, airspeed is less than 180kts, or TLA is greater than 70 degrees. SPEED BRAKES WILL NOT WORK IN DIRECT MODE
How do the ground spoilers work?
All panels are ground spoilers, operational on the ground only, deploys via WOW, Wheel speed above 60kts, TLA below 26deg and retract via Wheel Speed, TLA GROUND SPOILERS WILL NOT WORK IN DIRECT MODE
Describe how the rudder works, draw the picture from the study guide
electrically controlled, hydraulically actuated, PTU Power Control Unit, ACE Actuator Control Electronic, FCM Flight Control Module
What are the higher level functions for yaw?
yaw damp, turn coordination, gain on airspeed (as airspeed increases, rudder deflection decreases)
Describe how the flaps and slats works, draw the picture from the study guide
electrically controlled, electrically activated, PDU POWER DRIVER UNIT (the electric actuators that moves the flaps/slats on their track, ACE
How many slats are there?
8, 4 on each wing with 2 positions -15deg for flaps 1-3 and 25deg for flaps 4-full
What kinds of flaps do we have?
4 double-slotted/fowler-type flaps (2 per wing), 7 positions
What extends first, what retracts first?
Slats extend first, flaps retract first
What happens if the flaps are asymmetrical?
A skew sensor protects the flaps from an asymmetric position
What is the only primary flight control that is not FBW?
Ailerons
What is the difference between normal and direct mode?
There are no higher-level functions available in direct mode
What are the higher-level functions associated with pitch?
Gain on airspeed, elevator thrust compensation, AOA limiting
What are the higher level functions associated with yaw?
Yaw damp, turn coordination, gain on airspeed - as airspeed increases, rudder deflection decreases
What is the priority for the trim system?
Back-up, captain, first officer, autopilot
How is roll controlled?
Ailerons and multi-function spoilers (outer 3 spoilers on each wing)
How many spoilers are on each wing? What are their functions?
5, 3 outboard multifunction spoilers are used to assist in roll control, as speed brakes, and as ground spoilers; 2 inboard spoilers are only used as ground spoilers
When will the speed brakes automatically close even if the lever shows deployed?
Slat/Flaps selected to 2 or greater, airspeed less than 180kts, TLA greater than 70 degrees
What is the flap/slat extension/retraction sequence?
Slats extend first, flaps retract first
Will loss of airspeed data cause the flight controls to go into DIRECT mode?
Yes
Can a FCM override pilot input?
No, the pilot always has supreme control
What happens to artificial feel if the flight controls are disconnected?
Artificial feel is felt at 1/2 the normal load on the CA side
How are the flight controls trimmed?
Roll and yaw ailerons and rudder surface repositioned to a new “neutral position”, pitch horizontal stabilizer
Will the multifunction spoilers function in DIRECT mode?
Yes, for roll only and at a default fixed gain
Will the speed brakes/ground spoilers function in DIRECT mode?
No
What happens to the flight control system when the RAT is the only AC power source?
Horizontal stab trim operates at LO SPEED, Slat/flap system operates at LO SPEED, Slat/flap position is limited to 3 to allow adequate airspeed for the RAT
What happens if the trim dual rocker switches are activated separately?
The backup trim switch and the control wheel trim switches are dual split switches which have a 7 second time limitation when actuated separately. If only one half of the switch is actuated for more than 7 seconds, that switch is automatically deactivated.
A single trim command for yaw and pitch is limited to
3 seconds
The two aileron PCUs per side operate the aileron surface, in ___ and ____ configuration
in an active/active configuration - both pistons move but only 1 is doing the work
Hydraulic system 3 powers which elevator PCU?
Right Outboard
The HS-ACE responds to trim commands from the
Backup trim, CA, FO, and Autopilot (FCM) trim inputs
What is the correct sequence of slats/flaps extension and retraction?
Slats extend first, while flaps retract first
Following a jammed control column (pitch). When the Elev Disc Handle is pulled, what happens?
The unrestricted control column controls its own side elevator
The Elevator Thrust Compensation ETC function, stabilizing the aircraft around the pitch axis, will not be available when
in direct mode. It will only be available in normal mode, as it is computed in the FCM
Which systems are not driven by FBW Fly-By-Wire technology?
The ailerons only; all other systems are driven by FBW technology
In case of a single electric motor failure within the flap PDU, how will the system operate?
The flap/slat system will operate at low rate speed
The flight control system can operate in normal or direct mode. What happens in direct mode?
The FCM commands are removed from the control loop
How are the flight controls actuated?
Hydraulically actuated, these units are refered to as PCUs Power Control Units (except for ailerons driven by conventional control cables)
What are the speedbrakes?
Roll Spoilers 2,3,4 - verify this
What is the purpose of a P-ACE?
To control the respective PCU
What is the purpose of a PCU?
To hydraulically move the flight control surface
What is the purpose of the FCM?
The Flight Control Module provides higher level function inputs to the P-ACE, which controls the PCU
What replaces the control cables of a conventional aircraft?
The P-ACE
How many PCUs are controlled by a P-ACE?
2 PCUs
Where does the FCM get the info for the higher-level functions?
The ASCB Bus Avionics Standard Communications Bus from the MAU
Why might the FCM be removed manually from the flight control loop?
Airspeed Data Loss
What flight control surface does the pitch trim move?
The horizontal stabilizer surface (stab trim)
How many ACE units are there?
9 ACE units
What are the ACEs and their locations?
2 Primary-ACEs (fwd e-bay) P-ACE 1 Spoiler ACE (fwd e-bay) FCM 1 2 Slat/Flap-ACEs (mid e-bay) SF-ACE 2 Spoiler ACEs (mid e-bay) FCM 3/4 1 Primary ACE (aft e-bay) P-ACE 1 Horizontal Stab ACE (aft e-bay) HS-ACE
What do the 3 primary ACE units control?
The rudder and elevator surfaces
What do the 2 SF-ACE units control?
Slats and Flaps
What do the 3 spoiler ACE units control?
The multifunction spoilers
What does the HS-ACE control?
The horizontal stabilizer
How many channels are in each ACE unit? Why are there channels?
2 channels, for example P-ACE 1 controls the left outboard elevator PCU through channel 1 and controls the upper rudder PCU through channel 2
How many FCMs are installed?
4
What is a function of the FCM that IS NOT high level?
Adjusting surface control movement based on airspeed
When the flight controls are tested via the PBIT upon electrical power-up, are the hydraulics on? What happens if the hydraulics are turned on during the test?
No because control surface movement is not desired during the PBIT test.
How many hours until the PBIT expires? How would you manually activate the hydraulic PBIT test? How long does the test take?
50hrs, turn 3A ON then ACMP 1 ON, ACMP 2 ON within 6 seconds, 1min
What will interrupt the PBIT test?
If any flight control surface is moved, electrical power is interrupted, or the hydraulic pumps are turned off
What does the elevator control system move?
The elevator, which is attached to the horizontal stab, but only the elevator portion moved (horizontal stab moves separately for trim)
How many PCUs are used for the elevator? Do they all work together? How many FCMs?
4 PCUs, on each side one is active and the other is in standby, There are 2 FCMs for the elevator (one CA, one FO)
How are the 2 control columns connected (elevator)?
via a disconnect mechanism located between the 2 elevator torque tubes. In the event one side is jammed, the disc handle can disconnect the 2 columns so that the functioning column can control the aircraft via the onside elevator
Can the DISC handle be restored in flight?
No
What is the purpose of the elevator’s standby PCUs?
To act as a hydraulic damper and provides flutter protection
How is the elevaor PCUs alternated?
The FCM switches the PCU in use after each power-up or when a failure is detected.
What is the purpose of the elevator thrust compensation ETC higher-level function?
To reduce the pitching moment induced by increasing or decreasing thrust to reduce pilot workload
What is the difference between a failed PCU and a jammed PCU?
A failed PCU will not operate so the standby PCU will automatically take the active position. A jammed PCU will not allow flight control surface movement even if the other PCU is functional.
How is the horizontal stab actuated?
Via the HSA horizontal stab actuator via the HS-ACE. The HSA comprises of 2 DC motors in an active/standby configuration.
What trim inputs will the HS-ACE prioritize?
Backup, CA, FO, FCM (autopilot)
What does pushing the quick disconnect button on the yoke do to the HS flight controls?
Disconnects the HS-ACE (both channels) as long as the button is pressed (part of the pitch trim runaway EPC)
What do the pitch trim cutout switches do?
Disables the respective HS-ACE channel (so the standby switches to active)
In the event of an electrical emergency, which HS-ACE channel is powered?
Channel 2 at low rate
Besides an electrical emergency, what will cause the horizontal stab to operate at low rate?
Loss of airspeed data/loss of the FCM to protect the structure
What happens if one side of the trim switch on the yoke is pressed for more than 7 seconds?
The switch will deactivate automatically
ACE
Actuator Control Electronics
ASCB
Avionics Standard Communications Bus
ETC
Elevator Thrust Compensation
HSA
Horizontal Stabilizer Actuator
PCU
Power Control Unit
PDU
Power Drive Unit
