PC-21 Flight Control Systems (FCS) Flashcards
What axes are the flight control systems meant to control the attitude of the aircraft around?
Roll, pitch and yaw
What are the primary controls?
Aileron, rudder, elevator
What are the secondary controls?
Airbrake
Flaps
How is the PC-21 wing attached to the fuselage?
By its center section
What is the PC-21 wing dihedral, sweep back angle?
Sweep = 12.3 deg Dihedral = 4.5 deg
What is the high speed profile?
Aerodynamic profile of the wing that allows it to travel at high speeds
What is max roll rate with powered ailerons and roll spoilers?
200 deg/s
What material is the leading edge made of?
Glass fiber for bird strike protection
What does the stall strip do and where is it located?
- Improve effectiveness of TE control surfaces at high AOA.
- Located on leading edge of A/C
How many turbulators are there and what is their purpose, where are they located?
- 9 on each LE of wingwing
- Prevent a high-speed stall in roll.
- Leading edge of A/C
What are the wingtip spoilers manufactured from? What is their purpose?
- Carbon fiber
- To reduce the A/C’s drag by partial recovery of the tip vortex energy.
- Improve A/C handling characteristics
What do the ailerons have that isn’t functional?
Anti-balance tabs
What material are the roll spoiler manufactured from?
Carbon fiber composite material
What are roll spoilers designed to do?
Increase the roll rate.
What flaps does the PC-21 have?
- Single-slotted Fowler flap
- Flaps augment the wing surface and consequently the lift
What does the airbrake do?
Increase drag and reduces airspeed in flight.
What is the tailplane made from?
Aluminum
What is included on elevators to provide mass balancing?
Horn balance
What do balance and trim tabs do?
1) Reduce aerodynamic moment due to elevators
2) Trim A/C in the pitch axis
What does the vertical stabilizer have?
- Rudder with horn
- Trim tab
What does the Auto Flight Control System (AFCS) do?
Controls the A/C in roll, pitch and yaw by means of servos and trim actuator
What does the AFCS consist of?
- Flight Guidance Computer
- Pitch and roll servos
- Rudder trim actuator
- RIOCs 3 and 4
What sub-systems does the AFCS consist of?
1) Autopilot and Flight Direction System (AFDS) which controls pitch and roll axes of the A/C by using autopilot servos
2) Trim-Aid Device (TAD) which provides automatic rudder trim to reduce pilot input requirements to control for left turning tendencies.
3) These systems operate independently.
What does the flight control system comprise of?
- Control column and rudder pedals
- Flap selection lever
- HOTAS switches on the control column and the PCL
Where is the rudder trim switch located?
Front side of the PCL in each cockpit
What is the pitch and roll trim switches located?
Control column in each cockpit.
Where is the airbrake selector switch located?
- On the top of each PCL.
- Pulling it back extends the airbrake
- Pulling it forward retracts the airbrake
What does the TTI do? What are the green indications?
- Set of gauges which show the setting for roll, pitch and yaw.
- Green markers indicate the TO trim positions
What does the artificial feel unit do?
Gives pilot sensation of force feedback
What drives the aileron movement?
Hydraulic Servo actuator connected to drive rods.
How are the roll spoilers driven, and how are they powered?
Hydraulically driven
Each roll spoiler has its own hydraulic actuator, powered from the main hydraulic system.
When will roll spoilers start to move?
- Aileron reaches 4 deg of deflection, spoilers will start to move.
- When aileron reaches the 13 deg up position, spoilers are fully deflected
How are the elevators operated?
Via cables and drive rods
What is installed on the output lever of the forward control column to reduce the control force required to pull high g maneuvers?
Bob weight
How is the bobweight balanced?
By a balance spring that is attached to the forward cable turning lever.
What does each elevator have at its inboard trailing edge?
Balance tabs
How is the rudder controlled?
Via control cables and tie rods
What system is used to control trim in roll pitch yaw
Electrical actuators?
What do the elevator balance/trim tabs do when the primary control surface is moved in any direction?
Moves in the opposite direction
What does the balance/trim tab help to decrease?
The hinge moment of the control surface, to decrease the force the pilot has to apply in pitch and yaw.
What type of flap does the PC-21 have? Where are they? How are they operated?
- Single slotted Fowler flap
- Inboard trailing edge section of each wing
- Connected mechanically and are operated by a single hydraulic actuator through flaps lever
What are the 3 degree positions of the flaps?
Up = 0 deg TO = 18.5 deg LDG = 34 deg
Where is the airbrake switch located?
Situated on PCL.
How is airbrake powered?
Hydraulically powered
What is extended degree position of the airbrake?
65.5 deg
What sensor senses the position of the airbrake?
Proximity sensor
What does the TAD do?
- Provides automatic rudder trim to reduce prop torque effects and to compensate for the side effects of the prop slipstream.
What RIOCs provide TAD functions?
RIOC 3 and 4
Does the TAD completely remove requirement for pilot to rudder trim?
No
What two speeds is the TAD moved at?
- @ airspeed < 250 kts, tab is moved at 3.83 deg/sec
- @ airspeeds > 250 kts, tab is moved at 1.15 deg/sec
Which rate does manual trimming move the rudder trim tab?
Lower rate 1.15 deg/sec
What does the TAD do to provide neutral trim for take-off?
Moves the rudder trims to a preset TO position when WOW
What occurs when aircraft is airborne?
TAD is in air-mode
What parameters does TAD consider?
- Engine torque
- Airspeed
- AoA
- Underwing stores if fitted
What does TAD switch show when TAD is opeational?
Unlit switch
What does tad show when switch has been deactivated?
Cyan OFF on TAD switch.
What occurs when TAD has been switched off?
TAD is deactivated, manual trimming is still available.
Where is the powered ailerons and the roll spoilers status showsn?
MFD HYD
What indications are shown when airbrake is out/not fully stowed?
Amber AIRBRAKE indication appears on PFD and EMD
- OUT inidication is shown on MFD HYD
Which displays show a flaps position indication when in TO or LDG?
All three displays
Where are flaps indication continually shown?
MFD
Where is rudder pedals adjustment lever is installed?
Centre console in each cockpit, in order to allow the pilot to adjust the rudder pedals.
What does the gust lock do?
Prevents the primary flight controls from moving in gusty conditions.
What indication is shown when flaps are in transition?
Flaps indicator on all MFD, PFD, EMD shows a hollow white circle.
What are the airspeed and g limits with flaps not fully retracted?
180 KIAS
+4 to 0 g
How long on PFD and EMD are flaps indication show after reaching the up position?
9 seconds
Which displays show flaps position when not retracted?
PFD, EMD, MFD HYD
How can the pilot extend retract the airbrake?
Airbrake switch on PCL
- Aft lowers the airbrake
- Forward retracts the airbrake
What indication is shown as soon as airbrake leaves stowed position?
Amber AIRBRAKE on PFD, MFD, EMD
What aerodynamic effect occurs when airbrake is extended? How is this compensated?
Pitch-up moment
Counteracted by automatic pitch trimming system
What is degree of aileron trim available?
+4 to -4 deg
What degree of elevator trim is available?
+- 7.5 deg
What degree of yaw trim occurs?
19 deg right and 4 deg left.
What occurs when opposing trim selections are made in front and rear cockpit?
Trimming will stop until trim actuator is released.
How is the TAD activated? How is it selected off?
- Automatically when aircraft is powered
- Can be selected off by using the TRIM AID switch (Manual trimming still available)
- TRIM/AIL PWR switch also can deactivate it (manual trimming will not be available.
Are aerobatic maneuvers allowed with flaps extended?
No
What is the maximum demonstrated crosswind component for landing in clean configuration?
24 kt
When does amber FLAP caution occur?
If the flaps have not moved to the selected position within 16s when airbone or 20 s when on ground.
What does TRIM AID caution mean?
TAD failure
How can TAD be reset?
Turning off then on.
What can pilot do when there is a trim runaway?
Turn TRIM/AIL PWR to off
Are trim functions available when TRIM/AIL PWR switch has been turned off?
No
What does amber OVERSPEED FLAP advisory mean?
Flaps are not in UP position and speed > 183 kias.
What does a grey FLAP ALRT mean?
Flap alert function is not available.
The left and right elevators operate together. However, when one elevator becomes damaged what component allows the undamaged elevator to operate normally?
Torque tube
If the electrical power from the BATT BUS, GEN 1 and GEN 2 busses fail, what will occur to the flaps?
Retract automatically.
