B 777 Flight control

FLIGHT CONTROL QUESTIONS.

1. PFCS mode?
a. normal, secondary, direct
Normal mode operates when the necessary data are available for the PFCs and the ACEs. All the control laws, protection functions, and the AFDCs operate.
When the PFCS detects the loss of important air and attitude data, the PFCS operation changes to secondary mode. The PFCs and the ACEs operate but the PFC control laws and
protection functions downgrade. The autopilot cannot operate in secondary mode.
In direct mode, the PFCs are not used. The ACEs set the position of the control surfaces in direct response to analog pilot control inputs.
                                                                                                                                              
2. Purpose of PFC DISC switch is?
a. Reset PFCS to highest available mode
The PFC disconnect switch lets the pilot select the direct mode of operation.The pilots can manually switch the ACE to the direct mode. The PFC disconnect switch commands all ACEs to the direct mode.

3.The purpose of Backdrive actuators?
a. Drive control column to represents AFDC commands
The PFCs also calculate wheel backdrive commands. The PFCs send these commands to the AFDCs, which calculate control wheel movement commands for the backdrive actuator. The backdrive actuator moves the wheels the same amount as the pilot would move them manually for the same surface movement. The flight crew can override the autopilot through the use of enough force on the wheel to overcome the backdrive actuator.

4. If primary and secondary powers are not available to PFCS PSA, hot battery bus will supply?
a. Left and Center PSA
The left and center PSAs receive backup power from the hot battery bus.The right PSA has no backup power.

5. Feel and centering mechanism is attached to
a. Left shaft assembly
The feel and centering mechanism is at the bottom of the left shaft assembly. The aileron trim actuator connects directly to the feel and centering mechanism.

6. Wheel cable drum on each shaft assembly is connected via?
a. Upper force limiter
The wheel cable drums transmit the wheel cable motion to the force transducer and upper force limiter. The upper force limiter attaches directly to the two wheel cable drums.

7. How many position transducer(s) can be found on each shaft?
a. 3 each
The six wheel position transducers (total) measure the position of the control wheels. The transducers send analog electrical signals to the ACEs.

8. The landing attitude modification (LAM) logic will 
a. cause the flaps to go to higher setting
The landing attitude modification (LAM) logic decreases the flaperon droop when the airplane is in an overspeed approach with flaps at the 25-unit or 30-unit position. The PFC calculates the reduction of flaperon droop proportionally to the overspeed increment. Full flaperon droop removal occurs when the airspeed is 20 knots more than the approach landing speed shown in the airplane flight manual.
When the LAM logic is active, it reduces wing lift and causes an increase in angle-of-attack. This increases the nose gear ground clearance.

9. Aileron lock out in normal mode occurs depends on?
a. depending on the altitude and computed airspeed.
On the ground and during flight below cruise speed, the ailerons and flaperons are fully operational. At cruise speed, the ailerons fair to the wing surface and lock out. The flaperons supply roll control.

10. The bank angle protection
a. starts at a bank angle of 35 degrees
The BAP function supplies a control wheel force cue to the pilot when the bank angle is more than 35 degrees

11. The purpose of modal suppression function?
a. reduces the forward and aft body lateral movements

12. The purpose of the TAC function is to?
a. move the rudder to compensate for asymmetric thrust
When the thrust asymmetry compensation (TAC) switch on the P5 panel is in the AUTO position, the PFCs automatically control the rudder trim. This control is to make allowance for asymmetrical thrust from the engines. The TAC function does not operate when the TAC switch is in the OFF position. The manual trim cancel switch does not remove any rudder trimcaused by TAC.

13. The B777 elevators are made from
a. lightweight composite material structure
The elevators are light weight composite material structures.The skin is reinforced graphite/epoxy bonded to a core of Nomex honeycomb.

14. In the B777 rudder system, the normal pressure for the rudder operation in flight is 
a. reduced pressure of 1910 psi
The pressure reducer solenoid valve commands the pressure reducer valve to decrease the hydraulic pressure to 1910 psi. Reduced pressure on the actuator decreases the probability of leak and fatigue loads during normal operation.

15. The rudder pedal position is measured by
a. 4 pedal transducers
The flight crew uses two conventional rudder pedals to control yaw.Four rudder pedal position transducers change the flight crew rudder pedal commands to analog electrical signals. These signals go to the four actuator control electronics (ACEs). TheACEs change the signals to digital format and send them to the
three primary flight computers (PFCs) through the flight controls ARINC 629 buses.16.

17. STCM receive command from
a. ACE and alternate pitch trim levers
Two guarded cutout switches on the aisle stand control hydraulic shutoff valves on the stabilizer trim control modules (STCMs). When the pilot moves the switches to the cutout position, hydraulic pressure is shut off to the hydraulic motors.
Two stabilizer trim control modules (STCMs) receive commands from the ACEs and the alternate pitch trim levers to control the hydraulic pressure to the motors and brakes.

18. How many mode of elevator PCU?
a. 3
mode selector valve =  Normal, Bypass, Blocking.

19. how many horizontal stabilizer speed have?
a.4
Two hydraulic motors with two speeds move the horizontal stabilizer through a jackscrew mechanism. Four rates of horizontal stabilizer movement are available.

20. Compliance spring is incorporated in
a. elevator mechanism
There is a force transducer on each elevator torque tube. The force transducer attaches to the compliance spring at the aft end, and to the elevator feel unit connecting rod at the forward end.

21. Travel limit mechanism is incorporated in
a. alternate trim
When the horizontal stabilizer is operated from the alternate pitch trim levers, the travel limit drum assembly stops the stabilizer at the up and down limits. These limits prevent contact between the stabilizer ballnut and the ballscrew stops.

22. Aileron flight control PCU has a null LVDT. This is for
– rigging the PCU
The actuator piston also has a null LVDT to adjust the null position of the actuator piston LVDT
during adjustment of the control surface.

23. STCM component that maintenance personnel use to do a test of the operation of stabilizer hydraulic brake is called?
a. brake bypass valve
Maintenance personnel use the brake bypass valve to periodically test the operation of the hydraulic brake. When you push on the brake bypass valve button, the valve shuts off hydraulic pressure to the brake. While you hold the button, you verify that the brake stops and holds the hydraulic motor. When released, a spring moves the brake bypass valve back to the open position.

24. Elevator system is given?
a. a variable feel
The PFCs use data from the ADIRU to calculate elevator feel commands. The feel command goes through the ACE to the left and right feel actuators on the elevator feel units. The feel actuators supply to the column a variable feel based on airspeed.

25.  Servo loop function is done b?
a. ACE
The ACE contains a servo loop circuit to produce the command signals for the PCUs.
26. When the aircraft is on the air, which SOVs can be closed?
a.Only L and R SOV can be close
When 28v dc power is available, the flight control SOVs for the left and right systems can operate in the air or on the ground. The flight control SOVs for the center system can operate only on the ground.

27. At specified times Actuator confidence test and ACE monitor test must be done through MAT. The result of the test will appear at?
a.Maintenance task maintenance page
It is necessary to do the actuator confidence test (ACT) and the ACE monitor test (AMT) at specified times. Use the MAT to do these tests. The status of these tests shows on the maintenance task maintenance page.

28. In aileron sys the lost motion device which is attached to First officer shaft assembly is activated when lost motion is?
a. 2.9 degrees  in either direction
The right drum is bearing mounted on the right shaft assembly. The right drum has a peg on the bottom side which is part of the lost motion device. If there is a failure, the lost motion device lets the right drum connect to the right shaft assembly after a control wheel rotation of 2.9 degrees in either direction.

29. Captain drum movement is transferred to the left shaft assembly through?
a. Wheel force transducer
The wheel force transducer is on the left shaft assembly, between the flight deck floor and the nose gear wheel well.

30. Spoiler 4 and 11 mechanisms are connected to?
a. Right shaft

31. The commands to decrease force fight are generated in the
a.  PFCs
The signal also goes to the PFCs for force fight equalization.

32. Elevator offload function?
a. moves the stabilizer so that the elevator returns to neutral.
The elevator off-load function automatically sets the position of the stabilizer during manual flight or in autoflight. In this mode, the PFCs monitor elevator deflection and transfer pitch changes to the stabilizer. Once the stabilizer goes to its commanded
position, the elevator moves to neutral.

33. The horizontal stabilizers alternate operation is carried out by 
a. levers in the cockpit
The alternate pitch trim levers give the pilots mechanical control of pitch trim. The forward quadrant assembly transmits the movement from the levers to the control cables.


34. Slat skew detection system?
a. monitors all slats except 1 and 14
The slat skew detection system monitors the relative position of all the slats except for slats 1 and 14.

35. How many positions does Krueger  flap has?
a. krueger flap has 2 positions
The krueger flap has two positions: retracted and extended. It moves to the extended position when the slats are in the sealed or gapped positions. It moves to the retracted position when the slats are at the up position.

36. Flap/slat priority valve function is?
a. restrict the flow to the flap/slat if the system pressure is low.
The flap/slat priority valve controls the amount of hydraulic flow to the flap and slat primary control valves. The flap/slat priority valve gives priority of hydraulic power to the primary flight control system (PFCS) over the HLCS.

37. At flap lever position UP and 1 the position of the flap in Primary mode is?
a. UP

38. The secondary mode of flap/slat is not allowed on ground with engine shutdown. How to enable this mode for maintenance checks? 
a. override this inhibit function by using MAT

39.  EICAS caution message PRI FLIGHT COMPUTERS appears when?
a. ACE in direct mode
The EICAS caution message PRI FLIGHT COMPUTERS shows that all the ACEs that have power are in the direct mode and the PFC is not in the hydraulic OFF self-test mode. The message shows when the PFC disconnect switch is in the DISC position.

40. When maintenance personnel do a check on PFCS components how many flight control maintenance page can be view?  
a.3

41. Normal movement of captain shaft assembly is measured by?
a.Wheel position transducer

42. Lost motion device attach to L shaft assembly activated when control wheel rotation is?
a.7.8 degrees in either direction
The left drum has an additional attachment point for the wheel force transducer. The left drum is bearing mounted on a sleeve which is spline mounted on the left shaft assembly. If there is a failure, the sleeve and left drum can connect through a lost motion device. The lost motion device permits connection after a control wheel rotation of 7.8 degrees in either direction

43. Aileron system backdrive actuator attach to?
a.R and L shaft assemblies

44. Roll trim actuator authority on control wheel rotation is?
a.30o  in either direction

45. On a stationary aircraft, when the power of the engine is increased to take off thrust the flaperon?
a. droop under its own weight