Flight Controls Flashcards by Brendan Giel

Draw the Flight Control System (Elevator, Ailerons, Stabilizer, Rudder, Slats/Flaps)

see study guide

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What are the primary flight controls?

Ailerons, multifunction spoilers, elevator, rudder

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What are the secondary flight controls?

Horizontal stab, multifunction spoilers when used as ground spoilers, slats/flaps, ground spoilers

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The flight controls are moved via

Fly-by-wire FBW and conventional cables (aileron only)

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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.

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Which controls have higher level functions? Which do not?

Elevator, multifunction spoilers, rudder, horizontal stab (not flaps, slats, ground spoilers, or ailerons)

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What controls pitch?

Elevator, horizontal stab

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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)

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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)

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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

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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

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What is the trim priority?

Backup, captains, first officers, autopilot

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What controls roll?

Ailerons and multifunction spoilers

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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)

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What high level functions are applied to the ailerons?

The aileron has no high-level functions

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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

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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

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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

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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

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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

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What are the higher level functions for yaw?

yaw damp, turn coordination, gain on airspeed (as airspeed increases, rudder deflection decreases)

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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

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How many slats are there?

8, 4 on each wing with 2 positions -15deg for flaps 1-3 and 25deg for flaps 4-full

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What kinds of flaps do we have?

4 double-slotted/fowler-type flaps (2 per wing), 7 positions

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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?

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?

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?

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