Flight Controls Flashcards
Flight Controls
What are the three flight control modes?
Normal, Secondary, Direct.
How are the primary flight controls powered?
Redundant hydraulic sources.
How are the flaps and slats powered after a hydraulic failure?
Electrically (as backup).
How are the control column and wheels connected to each other?
Through jam override mechanisms.
How are the rudder pedals connected to each other?
Rigidly between the two sides.
How many Primary Flight Control computers are there?
3
How many Actuator Control Electronics units are there?
4
Which unit receives the pilot control orders directly?
ACEs (Actuator Control Electronics units)
Where do the ACEs send the pilot control orders?
To the primary flight control computers (PFCs)
Why do the PFCs receive other aircraft system data?
To compute appropriate control surface commands for enhanced handling qualities.
Where do the PFCs send control commands?
PFCs send the control commands back to the ACEs (to position the flight control surfaces).
Where are autopilot commands sent?
To the PFCs (which then produce control surface commands).
When do the flaperons droops?
For use as flaps increased lift, drops (move aft & down) in proportion to trailing edge flap extension.
When do the ailerons droop?
When flaps 5, 15 or 20 set for T/O.
What surfaces are locked out in normal mode?
Ailerons & spoilers 5 & 10 locked out during high speed flight.
Why does the rudder have a mechanical hinged tab?
Hinged tab deflects twice as far as rudder control surface for additional yaw control authority.
How are the pilot controls affected during autopilot operation?
Autopilot commands move the pilots controls to provide indications of what the autopilot is doing.
What is the effect of pilot override on the controls during autopilot operation?
Autopilot disconnects (PFCs disconnect the autopilot and use the pilot control inputs).
In which flight control modes is autopilot available?
Normal mode only.
When is the PFC self-‐test performed?
After hydraulic systems are shut down (2 mins after EICAS caution message HYD PRESS SYS +C+R shows).
What is the purpose of the flight envelope protection system?
Reduces possibility of inadvertently exceeding the aircraft’s flight envelope.
How does the system provide crew awareness of envelope margins?
Through tactile, aural and visual cures (no reduction in pilot control authority).
In secondary mode, which protections are not available?
• Autopilot. • Auto speed brakes. • Envelope protection. • Gust suppression. • Thrust asymmetry compensation (TAC). • Yaw damping (may be degraded or inoperative). • Tail strike protection.
Which surfaces are provided during mechanical backup operation?
Stabiliser and selected spoilers (4 & 11) are controlled by DCT cables FM FLT deck (allows pilot to fly S&L until electrical system is restarted).
On the ground, what are the trim switches on the control wheel for?
Stabiliser is directly positioned when the pilot uses the pitch trim switches.
What surface do the primary pitch trim switches move in flight?
Pitch trim switches do not position the stabiliser directly, but do make inputs to the PFCs to chance the trim reference speed.
How is the autopilot affected by the alternate pitch trim levers?
Autopilot does not disconnect, but does move stabiliser.
At what speed is nose up trim inhibited?
Minimum manoeuvring speed (stall protection limits trim reference speed –> inhibits trim in nose up direction).
How are column forces affected when flying near stall speed?
Column forces increase to higher level than would occur for an equivalent out-‐of-‐trim condition ABV the minimum manoeuvring speed.
When can the autothrottle support stall protection?
If armed and not activated (if speed decreases to stick shaker activation, autothrottle activates in appropriate mode [SPD or THR REF] advancing thrust to maintain minimum manoeuvring speed or speed set in MCP speed window, whichever is greater).
. When will overspeed protection occur?
At VMO/MMO.
When does elevator variable feel occur?
In normal mode (force increases as airspeed increases & column displacement increases).
In secondary and direct modes, what do control column command?
Proportional elevator deflection (instead of a manoeuvre command).
How is elevator feel different in secondary and direct modes?
Feels vary W/ flap position (increases W/ flaps up to discourage overcontrol, decreases W/ flaps extended to provide force levels appropriate for APP & LDG).
How many hydraulic systems power the stabiliser??
2 (C & R hydraulic systems).
If the automatic protection fails, how can stabiliser hydraulic power be removed?
Placing both stabiliser cutout switches to the CUTOUT position (aisle stand).
How is stabiliser greenband calculation performed?
Using FMC inputs of CoG, GW and T/O thrust.
How is the greenband calculation crosschecked?
Nose gear oleo pressure switch (switch must be selected to nose up or nose down band, then the pressure switch is compared to the computed greenband).
Which surfaces are cables driven through the control wheels?
Spoilers 4 & 11.
How is aileron trim indicated?
Indicated on a scale on the top of each control column.
When is aileron trim inhibited?
When autopilot engaged.
When is bank angle protection enabled?
When bank angle exceeds 35o (bank angle protection boundary).
How does airspeed affect rudder pedal forces?
Does not vary with airspeed (only proportional to rudder pedal displacement).
Which component reduces rudder authority at higher airspeeds?
Rudder ratio changer.
When does thrust asymmetry compensation occur?
When L & R engine’s thrust differs by > 10%, except when: • Airspeed < 70kts on GND. • Reverse thrust being used. • Engine thrust data lost.
Does TAC move the rudder pedals?
Yes (rudder movement back-‐driven through rudder pedals, proportionately to difference in engine thrust)
. In which mode and to what speed is wheel to rudder cross-‐tie available?
210kts in normal mode.
What does yaw damping provide?
Provides turn coordination and Dutch roll damping.
Does gust suppression move the rudder pedals?
No (only improves lateral ride quality through combination of roll & yaw movements).
In what modes are gust suppression and TAC available?
Normal mode only.
Which surfaces are used as ground speedbrakes?
All spoilers (7 sets on each wing [5 outboard, 2 inboard]).
If ARMED, when do the speedbrakes extend?
When LDG gear firmly on the GND (no tilt) and thrust levers idle.
Does the speedbrake lever move automatically for extension?
Yes (in normal mode only).
If not ARMED, what action causes speedbrake extension?
When either reverse thrust lever moved to reverse idle detent.
What is the purpose of the Krueger flap?
Provides a seal between inboard slat and engine nacelle on each wing.
What surfaces move with FLAP 1 selected?
Slats only.
What are the takeoff flap positions?
Flap 5, 15 and 20 (25 & 30 for LDG).
Above what altitude is flap extension inhibited?
20000’ (or 265kts).
When will the slats move to the fully extended position?
Flap 25 or 30.
When is secondary slat/flap mode automatically engaged?
Whenever primary mode fails to move the flaps or slats to the selected position.
How are the slats affected in secondary mode?
When flaps not up (in secondary mode), slats will: • Fully extend if airspeed < 246kts. • Move to the midrange position if the airspeed > 246kts (or will not extend beyond midrange position).
How do the slats and flaps extend in alternate mode?
Simultaneously. Pilot must manually select alternate mode. Alternate mode allows DCT manual operation of flaps & slats through the secondary drive electric motors.
In which flap positions is load relief available?
Flap 15 to 30 in primary mode only.
In which mode is slat load relief available?
Slat load relief in secondary mode only.
How does autoslat operation enhance stall characteristics?
Upon receiving signal FM the stall warning, slats automatically extend FM midrange to fully extended LDG position à reduces stall speed.
When will the expanded flap indication be displayed?
When any flap/slat is non-‐normal, including secondary and alternate mode.
