Flight Controls Flashcards
(42 cards)
When will the TAC (Thrust Asymmetry Compensator) automatically disengage?
1) when airspeed is below 70 knots on the ground, or
2) when reverse thrust is applied, or
3) when automatically disengaged due to system malfunction or loss of engine thrust data
4) if flight controls are no longer in the normal mode
How do the flight controls revert to the secondary mode?
Automatically, when the PFCs can no longer support the normal mode due to internal faults or loss of airspeed and/or inertial reference data.
Describe slat load relief.
Available in secondary mode only. If airspeed is > 256kts and slat are fully extended the slats will retract to the mid position.
Do these pitch trim switches move the control column?
Pitch trim does not move the control column.
Do trim switches have any effect when the autopilot is engaged?
The primary pitch trim switches are inhibited when the autopilot is engaged.
Explain how the pitch trim switches operate?
On the ground, the stabilizer is directly positioned when the pilot uses the pitch trim switches. In flight, the pitch trim switches do not position the stabilizer directly, but make inputs to the PFCs to change the trim reference speed.
What is Trim Reference Speed?
The speed at which the airplane would eventually stabilize if there were no control column inputs. Thrust changes result in a relatively constant indicated airspeed climb or descent, with no trim inputs needed unless airspeed changes.
What is the function of the Alternate Pitch Trim levers?
These levers move the trim reference airspeed (normal mode) and also move the stabilizer (all modes). The alternate pitch trim levers are linked to the stabilizer trim control modules (STCM) via control cables, and then mechanically to the stabilizer. Alternate pitch trim commands have priority over wheel pitch trim commands in all flight control modes
What is wheel to rudder cross tie?
When is it available?
Provides the capability of controlling the initial effects of an engine failure using control wheel inputs only. Will deflect the rudder up to 8° with control wheel only.
Wheel to rudder cross–tie is operative in flight below 210 knots in the normal mode, and speeds above 70 knots on takeoff
Is there a way to manually select the secondary flight control mode?
No
Can we manually select the direct mode?
Manually selected by moving the PRIMARY FLIGHT COMPUTERS DISCONNECT switch to DISC.
What are the flap speed limits?
1 - 265 5 - 245 15 - 230 20 - 225 25 - 200 30 - 180
What are the three modes of the flight control system?
- normal
- secondary
- direct
Explain the normal mode.
Manual vs autopilot
In normal mode during manual flight, four ACEs receive pilot control inputs and send these signals to the three PFCs. The PFCs verify these signals and information from other airplane systems in order to compute control surface commands. These commands are then sent back to the ACES. The ACES send enhanced signals to the PSUs.
When the autopilot is engaged, the autopilot system sends commands to the PFCs. The PFCs generate control surface commands, which are then sent to the ACEs in the same manner as pilot control inputs. The autopilot commands move the pilot controls to provide indications of what the autopilot is doing
The pilot controls command what system electronic components.
- four actuator control electronics (ACEs)
* three primary flight computers (PFCs).
What is flight envelope protection?
What are the three protections?
Flight envelope protection reduces the possibility of inadvertently exceeding the flight envelope by providing crew awareness of envelope margins through tactile, aural, and visual cues. Envelope protection does not reduce pilot control authority.
- stall protection
- overspeed protection
- bank angle protection
How are the flight controls actuated in direct mode?
In the direct mode, the PFCs no longer generate control surface commands. Pilot inputs received by the ACEs are sent directly to the PSUs.
What do you lose in direct mode?
GAATTEY, wheel to rudder cross tie, and manual rudder trim cancel switch
How does the mechanical backup work?
In the unlikely event of a complete electrical system shut–down, cables from the flight deck to the stabilizer (alternate pitch trim) and selected spoilers (4 & 11) allow the pilot to fly straight and level until the electrical system is restarted.
Describe stall protection.
Stall protection limits the speed to which the airplane can be trimmed. This trim inhibit speed is approximately the minimum maneuvering speed (top of the amber band) at lower altitudes, and can be 10 to 20 knots lower than the top of the amber band at higher altitudes
Describe overspeed protection.
At VMO/MMO, overspeed protection limits the trim reference speed so that trim is inhibited in the nose down direction. The pilot must apply continuous forward column force to maintain airspeed above VMO/MMO. Use of the alternate pitch trim levers does not reduce column forces.
Describe tailstrike protection
During takeoff or landing, the PFCs calculate if a tail strike is imminent and decrease elevator deflection, if required, to reduce the potential for tail strike. Activation of tail strike protection does not provide feedback to the control column.
Describe bank angle protection.
Bank angle protection provides roll control wheel inputs when airplane bank angle exceeds the bank angle protection boundary of approximately 35°. If the boundary is exceeded, the control wheel force rolls the airplane back within 30° of bank. This roll command can be overridden by the pilot. Maximum control wheel deflection always commands maximum control surface deflection.
The autopilot disengage bar disables bank angle protection.
Describe yaw dampening.
Provides turn coordination and Dutch roll damping.
