SmartCockpit Fokker 50 User manual

FLIGHT CONTROLS
The flight controls can be operated manually and automatically. From the flight deck, all
control surfaces are mechanically operated via rod-and-cable systems, except the electrically
operated aileron trim tab. To augment pitch attitude stability, an augment pitch attitude
stability system is installed. When the autopilot is engaged, ailerons, rudder, elevator, and
elevator-trim tab are controlled automatically.
Ailerons
The ailerons are operated manually from the captain’s and first officer’s control wheels. The
ailerons are equipped with spring tabs and balance tabs. The balance tab at the RH aileron
can be electrically operated as a trim tab. The aileron trim control panel is installed at the
rear of the pedestal.
Rudder
The rudder is operated manually from the captain’s and first officer’s pedals. A trim tab and a
balance tab, one above the other, are attached to the trailing edge of the rudder. The trim tab
can be operated mechanically from the trim control panel on the pedestal.
Elevator
The elevators are operated manually from the captain’s and first officer’s control column.
Pitch trim is obtained by an elevator trim tab at the RH elevator. The trim tab is operated by
trim wheels on both sides of the pedestal. A position indicator near each control wheel shows
the trim setting.
Augment pitch attitude stability
There are two pitch stability systems:
• Elevator Feel Control System.
• Longitudinal Stability Augmentation System.
Type I
An automatic Elevator Feel Control System (EFCS) is provided to balance the out-of-trim
forces caused by transients due to power and flap selections that would otherwise be felt at
the control column. The system operation is automatic and is active only during flight. Flap
and power lever positions are used as input variables. If the system fails, an alert will be
presented. The fault annunciation due to the power levers and flaps is inhibited during flight,
the alert will be presented on the ground approximately 15 seconds after landing. The
system can be switched OFF with the AUTO EL FEEL CTL pushbutton at the general
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switching panel. Once switched OFF, the system cannot be reinstated from the flight deck. If
the system is switched OFF, or has failed, the elevator operation is not affected. The elevator
control forces will now be defined by the position in which the feel control unit ceased
operation. On the ground an automatic self-test of the system is initiated when the flight
control lock is engaged, and the system is placed into a parked condition.
Type II
The Longitudinal Stability Augmentation System (LSAS) is provided to correct for the
dynamic out of trim farces caused by changes in engine power, flap position and aircraft
speed, and to augment the longitudinal stability at forward CG in flight. System operation is
automatic and active during flight only. Inputs are provided by:
• Both Electronic Engine Control (ENG EC) units.
• Attitude and Heading Reference System no 1 (AHRS 1).
• Flap drive unit.
• Air Data Computer (ADC).
NOTE: For those aircraft equipped with two ADC’s, ADC 1 is used as input for this
system.
The system uses the inputs to vary the bungee spring tension. Controls and indicators are
installed at the general switching panel, located at the overhead panel. A DEGRADED light
indicates a system input failure (flap position, airspeed or pitch). A FAULT light in the STAB
AUG pushbutton indicates a complete system failure. In this case LSAS will freeze in its last
position. The system can be switched OFF by depressing the STAB AUG pushbutton. With
the DEGRADED or FAULT lights illuminated, or the system switched OFF, the elevator
control forces during manual flight may be slightly higher or lower than normal, depending on
flight phase. Some system input failures (power lever and flap positions) detected in flight will
result in a system failure alert after landing (15 seconds after touch down). On the ground an
automatic self-test of the system is initiated when the flight control lock is engaged, and the
system is placed into a parked condition.
Pre-stall warning
If the aircraft attitude approaches a stall condition, a stick shaker at the LH control column is
activated. Shaker activation will disengage autopilot and yaw damper. The angle-of-attack
vane is located on the RH side of the fuselage nose. The pre-stall warning, which operates
independent of the integrated alerting system, is armed in flight only.
Flight control lock
A mechanically operated system of locks is provided for the ailerons, the rudder, and the
elevators. This system locks the ailerons and rudder in neutral position and the elevators in
down position. Each lock is spring loaded to the unlocked position. The EFCS or LSAS
control unit is commanded to a parking position. When the flight controls are locked, then the
power levers are prevented from being set to take-off power simultaneously. The flight
control lock lever is located at the rear LH side of the pedestal.
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Controls and indicators
Controls and indicators - Type I
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Controls and indicators - Type II
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Controls and indicators - Type I
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Controls and indicators - Type II
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Alerts
Alerts - Type I
Alerts - Type II
AUTOMATIC ELEVATOR
FEEL CONTROL
SYSTEM FAILURE
2
AURAL MWL/MCL CAP LOCALCONDITION(S) / LEVEL
CAUTION
FAULT
AUTO EL
FEEL CTL
LONGITUDINAL
STABILITY
AUGMENTATION
SYSTEM FAILURE
2
CAUTION
FAULT
STAB AUG
LONGITUDINAL
STABILITY
AUGMENTATION
SYSTEM FAILURE
1
AURAL MWL/MCL CAP LOCAL
CONDITION(S) / LEVEL
DEGRADED
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FLAPS
Operation
The flaps can be controlled by a seven position flap selector (UP, 5, 10, 15, 20, 25, 35). The
mechanically operated flap selector valve directs hydraulic pressure to the flap drive unit in
accordance with flap selector position. The position of the flaps is indicated by a flap position
indicator located at the center main instrument panel. Position markings are located at the
inboard side of the engine nacelles. A disagreement light illuminates when flap position is not
in accordance with flap selector position. The alert is inhibited during the period when the
flaps are in transit.
Alternate operation
Adjacent to the flap selector is an alternate flap control switch that operates the flap drive unit
electrically. The travel range is the same as in the hydraulic mode; however, the flaps extend
at a slower rate. After alternate operation, no hydraulic operation can be made before the
system is reset. Reset is obtained on the ground by moving the flap selector to an other
position.
Asymmetry protection
LH and RH flap positions are continuously compared and when an angular difference is
detected an alert is presented. When asymmetry is detected during hydraulic operation,
further flap movement is stopped.
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Functional diagram
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Controls and indicators
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Alerts
FLAP DISAGREMENT
2
AURAL MWL/MCL CAP LOCALCONDITION(S) / LEVEL
CAUTION
FLAP
FLAP ASYMMETRY
2
CAUTION
FLAP ASYM
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TAKE-OFF CONFIGURATION WARNING
Description
With the aircraft on the ground and either power lever in TO position, the TO CONF light at
the CAP illuminates when one of the following conditions is met:
• Elevator trim not in TO position.
• Rudder trim not in TO position.
• Flaps not in TO position.
• Parking brake not released.
• Neither TO nor FLX nor GA selected at the engine rating panel. See OM Part B section
POWER PLANT.
• Propeller autofeather system not armed. See OM Part B section POWER PLANT.
NOTE: The alerts cannot be cancelled by depressing MWL.
With the aircraft on the ground and either power lever not in TO position, the take-off
configuration can be tested by depressing the TO CONFIG button at the test panel for at
least 2 seconds. The TO CONF light at the CAP remains out when the take-off configuration
is complete.
NOTE: The test can be performed with the parking brake on.
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Controls and indicators
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Alerts
AIRCRAFT NOT IN
TAKE-OFF
CONFIGURATION
3
AURAL MWL/MCL CAP LOCALCONDITION(S) / LEVEL
WARNING
TO CONF
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SYSTEM OPERATION
Flight control lock
The flight-control lock should be engaged during taxiing and parking. After setting the flight-
control lock, move the control column slightly forward and bring the ailerons and rudder to
the neutral position; check the flight controls are locked. When releasing the lock, be aware
of flight control movement due to wind. The PF should keep his feet on the rudder bar while
the PNF should hold the control wheel.
CAUTION: Applicable for aircraft equipped with LSAS. If the flight control lock is engaged
while the flaps are traveling the system will see this as a wrong input during
the test phase of the LSAS, this might cause a non reset-able FAULT of the
LSAS.
Flaps
Normal operation
The flaps are hydraulically operated and the flap position is controlled by a flap selector.
Operating time from up (0) to 35 or reverse is approximately 15 seconds.
Alternate operation
The flaps are electrically operated and controlled by the alternate flap control switch.
Alternate flap operation inhibits normal flap selection. To avoid nuisance alerts select the
normal flap selector to the indicated flap position. Operating time from up (0) to 35 or reverse
is approximately 180 seconds.
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