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787 Technical Questions > 09 Flight Controls > Flashcards

09 Flight Controls Flashcards

1
Q

What are the three primary flight control system modes?

A

Normal, Secondary and Direct.

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2
Q

What is the function of the Primary Flight Computers?

A

They use information from other airplane systems (air data, inertial data, flap and slat position, engine thrust, and radio altitude) to compute control surface commands for enhanced handling qualities.

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3
Q

a. What flight control redundancy is available in the case of total hydraulic failure?
b. Which pilot controls are available in this situation?

A

a. An electrically actuated stabilizer and two spoiler pairs allow pilot control of pitch and roll.
b. The primary pitch trim switches, alternate pitch trim switches, and the control wheel.

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4
Q

What backup is available in the case of complete loss of flight control signalling?

A

Direct wiring from the flight deck
• stabiliser and a spoiler pair

  • pitch - alternate pitch trim switches
  • Roll - control wheel.
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5
Q

How many sections comprise the rudder?

A

A single section.

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6
Q

Which hydraulic system(s) power most of the flight controls?

A

Left, centre and right.

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7
Q

Name the electronic modules that convert pilot/autopilot inputs into control surface signals?

A

Actuator Control Electronics (ACE’s)

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8
Q

After landing, with flaps and speedbrakes retracted and groundspeed less than 30kts, why should the flight controls not be moved?

A

A series of flight control self-tests are run, which should not be interrupted to prevent a fault condition to be set.

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9
Q

In Normal mode, what are the three flight envelope protection features?

A

• Stall protection.
• Overspeed protection.
• Bank angle protection.


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10
Q

If the Flight Controls are operating in the Secondary mode:

a. Are the primary flight control computers still being used?
b. Are the envelope protection features still available?
c. What other functions are lost?
d. Can this mode be manually selected?

A

a. Yes, but they use simplified computations.
b. No.
c. G - gust suppression
P - pitch compensation
S - speedbrakes (auto)
R - roll/yaw asymmetry protection
A - Autopilot
T - tail strike protection
d. No.


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11
Q

If the Flight Controls are operating in the Direct mode:

a. Are the primary flight computers still being used?
b. Are any other functions lost in addition to those lost in Secondary mode?
c. Can this mode be selected manually?

A

a. No.
b. No, the same functions are lost in both Secondary and Direct mode.
c. Yes, by moving the PRIMARY FLIGHT COMPUTERS switch to DISC.

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12
Q

How is the yaw damping function affected in Secondary and Direct modes?

A

It is degraded in both modes.

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13
Q

a. Where is the primary pitch trim located
b. Can this control be used with the autopilots engaged?
c. On the ground, what control surface does this control move?
d. In normal flight, does this control position the stabiliser directly?

A

a. Dual pitch trim switches each pilot’s control wheel.
b. No, they are inhibited.
c. The stabiliser.
d. No, they change the trim reference speed in the PFCs.

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14
Q

a. Where is the alternate pitch trim located.
b. Can this control be used with the autopilots engaged?
c. How is this control connected to the stabiliser?
d. Does this control always move the stabiliser directly?
e. Which has priority, primary or alternate pitch trim commands?

A

a. Dual pitch trim switches on the aisle stand.
b. No, they are inhibited.
c. Electrically to the horizontal stabiliser trim actuator and then mechanically to the stabiliser.
d. No, its operation is the same as the primary pitch control.
e. Alternate.

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15
Q

In Normal mode, how is the:

a. overspeed protection feature implemented?
b. stall protection feature implemented?

A

At Vmo/Mmo, overspeed protection limits the trim reference speed so that nose down trim is inhibited. Continuous forward control column force is required to maintain airspeed above Vmo/Mmo.
b. Stall protection limits the trim reference speed so that nose up trim is inhibited at the minimum manoeuvring speed.

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16
Q

How does the elevator feel control differ when there is a change from Normal to Secondary or Direct Modes?

A

The elevator variable feel system provides feel force levels based on flap position instead of a continuous variation with airspeed.


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17
Q

In Secondary and Direct modes, how do the primary and alternate pitch trim switches move the stabiliser?

A

Directly.

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18
Q

a. Which system powers the stabiliser? b. Can this power supply be removed?

A

a. The electrical system, using a dual channel electric control unit powered by the L2 and R2 AC buses.
b. Yes, by placing the L2 and R2 stabiliser cutout switches to the CUTOUT position removes all power.

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19
Q

a. What does the EICAS warning message STABILIZER mean?
b. Under what circumstances would the message STABILIZER CUTOUT replace STABILIZER?
c. In the Normal flight control mode, is pitch trim still available if the stabiliser is manually shut down, or failed?

A

a. Both stabiliser channels have automatically shut down or failed, or, automatic shutdown fails to stop the uncommanded motion.
b. When the L2 and R2 stabiliser cutout switches are placed to the CUTOUT position.
c. Yes, through the elevators.

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20
Q

What is the purpose of the Column Cutout function?

A

To stop the effects of uncommanded pitch trim input from jammed or failed pitch trim switches.

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21
Q

a. Where is the stabilizer trim position displayed?
b. What does the green band indicate?
c. Under normal circumstances, when is the EICAS trim position indication displayed?

A

a. The EICAS and on the flight controls synoptic.
b. The stabiliser position is correct for the actual takeoff weight & CG.
c. From power up to 10 seconds after gear up, or 60 seconds after liftoff.

22
Q

When does the EICAS advisory STAB GREENBAND display?

A
  • The computed green band disagrees with pressure transducer data, or
  • the two transducer values are not within the set tolerance, or
  • either transducer has failed
23
Q

How is over control in roll protected at high speeds?

A

The ailerons are locked out at high speeds.

24
Q

Does the B787 manual aileron trim?

A

No, aileron trim is incorporated into the flight control laws and no pilot input is required.

25
Q

a. How is bank angle protection achieved?
b. Can you override this protection?
c. Is bank angle protection provided in Secondary and Direct modes?

A

a. If the angle of bank exceeds 35 degrees, a control wheel force rolls the aircraft back to within 30 degrees of bank.
b. Yes.
c. No.

26
Q

a. In Normal mode, what commands do the rudder pedals send to the rudder?
b. What rudder pedal commands are generated in Secondary and Direct modes?

A

a. They command a sideslip manoeuvre with the airplane sideslip angle dependent on pedal displacement.
b. They command a proportional rudder deflection instead of a manoeuvre command.

27
Q

a. What is the purpose of the Rudder Ratio Changer?

b. How is the function implemented in the Secondary mode?

A

a. It automatically reduces the sideslip command (for a given pedal input) as airspeed increases.
b. It is based on flap position. With flaps up, the rudder response to pedal inputs is less than the response when the flaps are not up.

28
Q

Under what conditions do the rudder pedals not move in response to asymmetry compensation inputs?

A

During reverse thrust asymmetry conditions, or during takeoffs in crosswind or gusty conditions

29
Q

a. On the ground, when is the asymmetry compensation function available?
b. In the event of an engine failure on take-off, does the system counter all the yawing motion?
c. Do the rudder pedals move in this situation?

A

a. Above 60kts groundspeed.
b. No, the pilot can still recognise the initial onset of an engine failure through the airplane yaw cue, since the flight controls do not counter all of the yawing moment.
c. Yes.

30
Q

a. In flight, how does the asymmetry compensation function initially respond to a roll or yaw asymmetry condition?
b. After initial inputs, what does the system do then?
c. Do the rudder pedals move in this situation?
d. What is then displayed on the EICAS?

A

a. An automatic rudder input counters the yawing moment and an automatic lateral control input counters the rolling moment.
b. The system off loads any steady state lateral control input to the rudder, resulting in a small sideslip.
c. Yes.
d. The resulting rudder trim indication.

31
Q

During large asymmetry conditions, the EICAS caution message ROLL/YAW ASYMMETRY may display. What does it indicate?

A

Some automatic lateral control input may remain after the off load stops to counter the asymmetry condition.

32
Q

For severe asymmetry conditions, what does the EICAS caution message ROLL LEFT/RIGHT AUTHORITY mean?

A

Limited roll control is available due to large automatic lateral inputs already being applied by the system.

33
Q

a. In what flight control mode(s) is automatic lateral and rudder inputs available?
b. Can the pilot override these automatic inputs?

A

a. Normal mode only.

b. Yes.

34
Q

In what flight control mode(s) is the wheel to rudder cross-tie available?

A

Secondary and Direct modes.

35
Q

a. Where is the manual rudder trim control located?

b. What trim rates are available?

A

a. The aft aisle stand.

b. Two, low speed to the detent, high speed when the knob is rotated past the detent.

36
Q

a. What happens to any manually applied rudder trim inputs on take-off?
b. What happens to any automatic or manual rudder trim inputs on landing?

A

a. Automatically zeroed at 30 knots.
b. They are zeroed so they do not provide a yaw command when the airplane transitions from the air mode (sideslip manoeuvre) to the ground mode (yaw manoeuvre).

37
Q

Where are the rudder trim indications displayed?

A

On the EICAS and flight controls synoptic.

38
Q

How are the spoiler powered?

A

Hydraulic systems supply 5 pairs of spoilers. The remaining two spoiler pairs are individually powered by two electrical buses.

39
Q

a. What does the EICAS advisory SPOILERS mean?

b. When would the EICAS advisory SPOILER PAIRS appear?

A

a. Failure of two spoiler panels in the air, or failure of one not down and locked spoiler panel on the ground.
b. Failure of three or more spoiler panels

40
Q

a. With the speedbrake lever armed, what conditions must be satisfied to deploy the speedbrakes automatically on landing?
b. Would they deploy if the lever was left DOWN?
c. If, after touchdown, a Go-around was initiated, would the spoilers retract automatically?
d. Is Auto speedbrake available in Secondary and Direct modes?

A

a. When the main gear trucks untilt and both thrust levers are not in the takeoff range.
b. Yes,
• on the ground with groundspeed above 85 knots, either thrust lever was previously in the takeoff range, then both thrust levers are moved to the idle range (refused takeoff), or
• on the ground and both thrust reverse levers are moved to the reverse idle detent
c. Yes,
• on the ground, when either thrust lever is moved to the takeoff range, or
• on the ground, if there is a transition to in the air, or in the air, when either thrust lever is beyond 90% full travel.
d. No.

41
Q

a. What is the purpose of the Autodrag function?
b. How does Autodrag accomplish this?
c. When is Autodrag active?
d. When is the function removed?
e. Is this function available during both manual and automatic approaches?
f. Which flight control mode(s) is Autodrag available?

A

a. Assists in glideslope/glidepath capture when the airplane is above the vertical path.
b. By deflecting the ailerons downward and raising the two most outboard spoilers, while maintaining airspeed.
c. Flaps 25 or 30 and the thrust levers are at idle.
d. It is gradually removed below 500 feet AGL.
e. Yes.
f. Normal mode only.

42
Q

a. When does the flap indicator first appear on EICAS?

b. When does the flap indicator finally blank on EICAS?

A

a. Automatically when the flaps are not retracted.

b. 10 seconds after the slats are fully retracted.

43
Q

What do the following flap indicator displays mean?

a. Flap selection number (and line) magenta?
b. Flap selection number (and line) green?

A

a. The slats and flaps are in transit to the commanded position.
b. The slats and flaps are in the commanded position.

44
Q

During normal operation, in which flap selections will the slats be at: -

a. the middle position?
b. fully extended?

A

a. 1, 5, 15, 20.

b. 25, 30.

45
Q

When the flap lever is moved from 20 to 25, what happens to the:

a. flaps?
b. slats?

A

a. Do not move.

b. Move to the fully extended position.

46
Q

a. What are the 3 modes of flap/slat operation?

b. What powers the devices in each mode?

A

a. Primary, Secondary, Alternate.
b. Primary = hydraulic,
Secondary = hydraulic or electric,
Alternate =electric

47
Q

When is Secondary mode automatically selected?

A

P - primary control, or primary mode fails
U - un-commanded flap/slat motion is detected.
S - Slow movement, less than 50% of the normal rate,
H - hydraulic (Centre) system failed
D - disagree (Flap/Slat) detected

48
Q

a. What selections are necessary to extend the flaps and slats in the Alternate mode?
b. Will the slats and flap extension movements be sequenced?
c. What happens if EXT is selected after the flaps reach position 20?
d. If RET is selected, which moves first: slats and/or flaps?

A

a. The alternate mode must be manually selected. The three–position alternate flaps selector extends and retracts the flaps and slats.
b. No, the flaps and slats extend simultaneously.
c. Nothing, alternate flaps extension is limited to flaps 20.
d. Flaps then slats.

49
Q

The flaps are selected from 5 to 20 for the approach when the EICAS message FLAPS PRIMARY FAIL appears. What happens to the flaps and slats?

A

Slats remain in the middle position; the flaps continue to move to position 20 in Secondary mode on electrical power.

50
Q

In which modes is: -

a. Flap Load Relief available?
b. Slat Load Relief available?

A

a. Primary mode.

b. Secondary mode.

51
Q

In Primary mode, the aircraft approaches a stall with the flaps and slats at position 1.

a. Will any of the devices move?
b. Is this function available in Secondary mode?

A

a. The Autogap function fully extends the slats.
b. No, the Pregap function would have already extended the slats to the fully extended position with the selection of flap 1.

52
Q

a. Do the pilots have any control over the Cruise Flap function?
b. When is this function active?

A

a. No, it is an automated function.

b. Normal mode, above 25,000 feet, between 0.54 and 0.87 Mach.

787 Technical Questions (20 decks)

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