Flight controls Flashcards
How are columns and wheels connected?
Jam override mechanisms. The not jammed side can maintain control by applying force to that wheel or column.
How are rudders connected?
Rigid connection
Flight control system electronic components?
Four Actuator Control Electronics(ACEs), three Primary Flight Computers(PFCs)
What causes FLIGHT CONTROLS message?
Multiple ACE and/or hydraulic system failures to cause the loss of a significant number of control surfaces, or
Other flight control system faults are detected.
Pitch is controlled by?
Two elevators and one horizontal stab
Roll is controlled by?
Two flaperons, two ailerons, 14 spoilers
Yaw is controlled by?
Single rudder, and partial span tab
What spoilers lock out during high speed flight?
5 and 10. They augment roll control in low speed flight.
When does rudder become effective?
Around 60 knots
How far does partial span tab move?
Twice the deflection of the rudder
Three primary flight control modes?
Normal, secondary, direct
What protections are there in normal mode?
Stall, overspeed, bank angle
Describe stall protection
When below minimum maneuvering speed, nose up trim is inhibited. More force than normal on the control column to stay below trim inhibit speed.
Describe overspeed protection
At Vmo/Mmo nose down trim is inhibited. It can be overridden by pushing forward. Alternate pitch trim does not reduce column forces.
Describe bank angle protections
There is a bank angle protection boundary of roughly 35 degrees. When exceeded the control wheel forces the bank back to within 30 degrees. Can be overridden by the pilot. AP disengage bar turns this feature off. Bank indicator turns amber past 35.
How does pitch control work
PFCs generate pitch maneuver.
PFCs position elevators and stabilizer for said pitch maneuver.
Compensates for thrust changes, gear config changes, and turbulence, bank up to 30 degrees, and flap and speedbrake changes.
In the flare it commands nose down so you have to apply aft pressure.
Primary pitch trim control
Both switches must be used
Inhibited with AP on
Does not move control column
Moves stabilizer on the ground
Inflight it changes trim reference speed.
Moves elevators, then stabilizer to streamline the elevator
Alternate pitch trim
Move trim reference airspeed in normal mode
Moves stabilizer in all modes
Priority over control wheel pitch trim commands
Does not disconnect autopilot, but moves stabilizer
Secondary and direct pitch control
Commands proportional elevator deflection instead of a command
Does not compensate for thrust, bank, or config changes
Two force feels based on flap position.
Move the stabilizer instead of trim reference speeds
Stabilizer power source
Center and right hydraulic sources
Stabilizer trim control modules control hydraulics
Stabilizer shutdown
If uncommanded stabilizer motion is sense, the particular module will shutdown and give STABILIZER R or C. Stabilizer still works through other module.
STABILIZER is displayed when both modules shutdown or fail. Or if auto shutdown fails to stop the motion.
Stabilizer position Indication
Three segments to green band. Mid, nose up, and nose down.
Calculated using FMC inputs of CG, gross weight, TO thrust and V1.
Nose gear pressure switch cross checks the CG to ensure correct green band has been selected.
What spoilers are connected via cable?
4 and 11
Thrust Asymmetry Compensation
Adds rudder at 10% thrust difference.
TAC is not available below 70kts, reverse thrust is applied, or system malfunction or loss of engine thrust data.
Wheel to rudder crosstie
Control wheel inputs deflect rudder up to 8 degrees when below 210 knots
Yaw damping
In normal mode provides turn coordination and dutch roll damping
Three flap slat modes
Primary, secondary, alternate
Primary mode
Powered by center hydraulic system
Secondary mode
Engaged when primary mode fails to move flaps or slats to commanded position.
Engaged until affected system surfaces are fully retracted or center hydraulic system restored.
Electrically powered.
Autoslats are not available.
Fully extended at all flap positions. Retract to midrange over 256. Stay there until past 20 or Up.
Alternate mode
Uses the switch
Limited to flaps 20 and slats midrange
Flap load relief
Limited to primary mode
In flaps 15 to 30, over the flap speed they retract to a position appropriate for the speed. Starts 1 knot over placard speed.
Retraction limited to flaps 5.
Will re-extend 5 knots below placard speed and only go so far as flap handle position.
Autoslats
Signaled from stall warning system. Slats go from mid to full. Retract a few seconds once signal goes away.
Only in primary and flaps 1,5,15,and 20
