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Systems > Flight Control System > Flashcards

Flight Control System Flashcards

1
Q

What are the three sections of the flight control system?

[H] “MAF”

A
  • Mechanical control system
  • Flight control servo system
  • Automatic flight control system

.

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2
Q

Where are the cyclic, collective, and tail rotor pedal flight controls routed?

A

Aft and outboard of each pilot seat, vertically up each side of the aircraft

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3
Q

What does the tail rotor control system provide?

A

Directional control by varying the pitch of the tail rotor blades

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4
Q

What (2) sources power the tail rotor servo?

A
  • No. 1 hydraulic system
  • Backup hydraulic system

The use of dual systems ensures reliability in directional control.

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5
Q

What happens when either tail rotor cable becomes severed?

(Think Caution)

A

Microswitches activate the TAIL ROTOR QUADRANT caution

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6
Q

How many primary servos are located in the hydraulics bay? Check me

A

Three primary servos

Each primary servo has redundant features for safety.

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7
Q

What occurs if one primary servo stage becomes inoperative?

[Think Caution]

A

A bypass valve opens, and the #1/#2 PRI SERVO PRESS caution appears

This mechanism ensures continued control despite a failure.

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8
Q

What does the pilot-assist servo assembly contain?

Three part anwser// [H]: 2 ANSWER share a button

A
  • Boost servos
  • SAS actuators
  • Hydraulic (pitch and roll) trim actuators

These components help reduce pilot workload and enhance control.

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9
Q

What is the function of boost servos?

A

Reduce cockpit control forces and SAS system feedback

Boost servos are critical for making control inputs easier.

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10
Q

Fill in the blank: The cyclic, collective, and pedal controls are mechanically combined in the _______.

A

[mixing unit]

This combination allows for effective airframe response characteristics.

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11
Q

Delete

What type of mixing is present when trim is engaged? Revise question

A

Electrical (collective/airspeed-to-yaw) mixing

This mixing enhances the responsiveness of the helicopter to pilot inputs.

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12
Q

What does AFCS stand for?

A

Automatic Flight Control System

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13
Q

What type of system is the AFCS?

It combines the elements of mutiple systems / three parts make it work

A

Electro+hydro+mechanical system

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14
Q

What are the three major subsystems of the AFCS?

A
  • Stability Augmentation System (SAS)
  • Stabilator system
  • Advanced Flight Control Computer (AFCC)
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15
Q

True or False: Each subsystem of the AFCS operates independently.

A

True

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16
Q

What feature of the AFCS provides pitch, roll, and yaw stability augmentation?

A

Stability Augmentation System (SAS)

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17
Q

List three features provided by the AFCS.

A
  • Pitch and roll attitude hold
  • Airspeed hold
  • Automatic approach to hover
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18
Q

List two types of altitude hold provided by the AFCS.

A
  • Barometric altitude hold
  • Radar altitude hold
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19
Q

What is the function of the automatic depart feature in the AFCS?

A

Facilitates automatic departure

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20
Q

What does the term ‘turn coordination’ refer to in the context of the AFCS?

A

Coordinating turns for stability

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21
Q

What feature of the AFCS aids in maneuvering stability?

A

Maneuvering stability

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22
Q

True or False: The AFCS includes an automatic preflight check.

A

True

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23
Q

What does the pitch and roll hover augmentation feature do?

A

Augments hovering capabilities and alleviates gusts

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24
Q

What happens when there is an AFCS mode failure?
DEL

A

AFCS DEGRADED caution appears and the appropriate mode failure capsule is activated

Except for stabilator failures.

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25
Q

What is the central component of the AFCS?

A

Digital advanced flight control computer (AFCC)

Commands SAS actuators and trim actuators.

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26
Q

What are the two types of control employed by the AFCC? Refer to Loops

A
  • Inner-loop (SAS)
  • Outer-loop (autopilot)
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27
Q

What is the primary purpose of the stabilator system?

A

To provide angle of attack stability

Helps stabilize the aircraft in both angle of attack and maneuvering stability.

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28
Q

What are the four inputs required to position the stabilator?

C.L.A.P

A
  • Collective position
  • Lateral acceleration
  • Airspeed
  • Pitch rate
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29
Q

What is the function of the SAS?

A

Increases stability by sensing acceleration rate and applying control inputs

Works in pitch, roll, and yaw axes.

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30
Q

True or False: SAS 1 is a digital system.

A

False

SAS 1 is an analog system.

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31
Q

What happens if either SAS channel malfunctions?

A

AFCS DEGRADED caution appears and the appropriate SAS fail advisory light illuminates.

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32
Q

What are the two types of altitude hold available in the autopilot system?

A
  • Barometric altitude hold (BAR ALT)
  • Radar altitude hold (RAD ALT)
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33
Q

Fill in the blank: The stabilator travels from _____ for hover and low-speed flight to _____ for cruise and maneuvering flight.

A

42° trailing-edge down, 10° trailing-edge up

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34
Q

What is the maximum rate of change for the autopilot’s airspeed hold feature?

A

6 KIAS per second

Above 50 KIAS.

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35
Q

What is the maximum control authority for SAS channels when both are engaged?

A

±10 percent control authority

Each channel provides ±5 percent.

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36
Q

When is heading hold disengaged?
(On the ground vs in flight)

A

With weight on wheels or below 50 KIAS by depressing tail rotor pedal microswitches.

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37
Q

True or False: The trim system uses only electric servos.

A

False

It uses both electric and hydraulic servos.

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38
Q

What occurs during a total AC power failure regarding the AFCC?

A

AFCC computer power is interrupted and must be cycled after power restoration.

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39
Q

What is the role of the collective inner-loop actuator (CILA)?

A

Required for hover augmentation, gust alleviation, turn coordination, roll attitude hold, altitude hold, and coupler functions.

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40
Q

What happens if the stabilator system malfunctions? 3 Things

A

Automatic power shutdown to both actuators, warning tone, and STABILATOR caution appears.

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41
Q

What should the PNAC do in the event of a runaway down stabilator?

A

Disengage the automatic mode by activating manual mode slewing.

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42
Q

Fill in the blank: The stabilator may fail without illumination of the associated caution and aural warning tone, with the initial indication being an uncommanded _____ change during flight.

A

pitch

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43
Q

What is the purpose of the stabilator position indicator? DEL

A

Assists the pilot in manually slewing the stabilator to a desired position.

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44
Q

What is the altitude range for engaging RAD ALT hold?

A

0 to 5,000 feet Above Ground Level (AGL)

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45
Q

In hover coupler mode, how is altitude the aircraft is sitting at determined

A

HVR ALT knob

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46
Q

What are the maximum climb and descent rates when transitioning to another altitude in hover coupler mode?

A
  • Climb: 1,000 feet per minute
  • Descent: 200 feet per minute
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47
Q

What happens if RAD ALT hold mode fails?

A

BAR ALT hold is automatically engaged

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48
Q

What can cause altitude hold to disengage?

A

Malfunction in the engine torque indication system

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49
Q

What is a potential consequence of using the four-way cyclic TRIM switch continuously?

A

The aircraft may enter a descent with altitude hold engaged

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50
Q

True or False: RAD ALT hold may decouple when flying over the deck of a ship.

A

True

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51
Q

What indications will illuminate if RAD ALT hold decouples? DEL

A
  • AFCS DEGRADED caution
  • MASTER CAUTION
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52
Q

What environmental condition may make BAR ALT hold difficult to engage?

A

Electromagnetic environment

53
Q

What is the purpose of maneuvering stability?

A

To increase pilot effort required to maintain a given pitch rate at bank angles > 30°

This feature alerts the pilot to g-loading during maneuvering flight.

54
Q

At what altitude and airspeed can I engage automatic approach

A

Activate the automatic approach pushbutton (APPR/HVR) at any airspeed and altitude < 5,000 feet AGL

55
Q

What happens if torque reaches or exceeds limitations during an automatic approach?

A

The AFCC stops increasing collective

This ensures the aircraft does not exceed torque limitations.

56
Q

What does the hover coupler engage based on?

A

Longitudinal groundspeed within 1 KGS of selected LONG VEL after automatic approach or within 5 KGS if engaged manually

Radar altitude hold engages when altitude is within 2 feet of selected altitude.

57
Q

What occurs when the automatic depart mode is engaged?

A

The aircraft accelerates to 120 KIAS and climbs to 150 feet AGL

The AFCC monitors dual-engine torque and adjusts collective accordingly.

58
Q

What happens if the stored roll attitude is < 5° angle of bank during automatic departure?

A

The AFCS levels the wings and maintains heading as the aircraft accelerates through 50 KIAS

If > 5° angle, it maintains coordinated turn for established bank angle.

59
Q

What does the crew hover feature allow, AWs to do?

A

Allows the aircrewman to position the helicopter while in a coupled hover

Controlled using the HOVER TRIM CONTROL panel.

60
Q

What initiates the automatic preflight check of SAS components?

A

Pressing the SAS 1 pushbutton with conditions met:
* Weight on wheels
* Rotor brake on
* Engine torques < 10%
* Both EGI attitudes valid
* SAS 1 pushbutton engaged after AFCC on for at least 20 seconds

If conditions change, the AFCC CMPTR PWR/RESET button must be cycled.

61
Q

How long does the automatic preflight check take to complete?

A

Approximately 10 seconds

It checks the response of rate gyros against a digital model.

62
Q

Fill in the blank: The AFCS positions the cyclic, collective, and tail rotor pedals prior to the _______ sequence

A

[blade-fold sequence]

63
Q

What inputs are transferred to the swashplate assembly?

A

Fore, aft, and lateral inputs

These inputs are essential for adjusting the helicopter’s pitch and roll.

64
Q

What mechanism is used to transfer yaw inputs to the tail rotor servo?

A

Tail rotor cables

This mechanism is vital for controlling the helicopter’s yaw.

65
Q

How is the tail rotor servo actuated/ what moves the pitch change shaft?

A

Mechanically actuated but requires hydraulic pressure to operate the pitch change shaft

66
Q

What is the function of the tail rotor quadrant?

A

Transmits tail rotor cable movement to the tail rotor servo

67
Q

What do the spring cylinders connected to the quadrant do?

A

Maintain cable tension if either tail rotor cable becomes severed

68
Q

What activates the TAIL ROTOR QUADRANT caution? Z

A

Microswitches when either cable is broken

69
Q

How is directional control of the tail rotor maintained if one cable is severed?

A

By the remaining spring

70
Q

What happens if both tail rotor cables are severed?

A

Two separate centering springs counter the tail rotor servo pilot valve positioning the tail rotor to a neutral setting

71
Q

What capability does a neutral setting of the tail rotor provide?

A

Fly-home capability

72
Q

What does the flight control servo system consist of? (3)

A

Primary servos, tail rotor servos, and pilot-assist servos

73
Q

What happens if the first stage of the tail servo loses hydraulic pressure?

A

The backup pump powers the second stage

74
Q

What cautions and advisories illuminate when the backup pump powers the second stage?

A
  • # 1 TAIL RTR SERVO caution
  • # 2 TAIL RTR SERVO ON advisory
  • BACKUP PUMP ON advisory
75
Q

Can flight controls operate without hydraulic pressure to the pilot-assist servos?

A

Yes

76
Q

What is required to move the primary servos?

A

Hydraulic power

77
Q

How are pilot-assist servos turned on and off?

A

By pressing the SAS/BOOST pushbutton

78
Q

If SAS/ boost controls pressure to the servos then what controls hyd px to pitch and roll trim actuators?

A

TRIM pushbutton

79
Q

How many boost servos are there, now list them. [H: Which control movements are boosted]

A
  • Collective
  • Yaw
  • Pitch
80
Q

What is the function of the SAS actuator? DELETE

A

Provides rate damping

81
Q

What controls are mechanically combined in the mixing unit? Like the things that I touch

A
  • Cyclic
  • Collective
  • Pedal
82
Q

Fill in the blank: The pilot-assist servos, except _______ and roll trim, are turned on and off by pressing the SAS/BOOST pushbutton.

A

Pitch

83
Q

What does AFCS stand for?

A

Automatic Flight Control System

AFCS is an electrohydromechanical system for helicopter flight control.

84
Q

What is the function of the inner-loop (SAS) in the AFCC?

A

Employs rate damping to improve dynamic helicopter stability

It operates without movement of the flight controls.

85
Q

What does the outer-loop (autopilot) do?

A

Provides long-term inputs by trimming the flight controls

It can drive the flight controls through their full range of travel.

86
Q

How fast can the outer-loop drive the flight controls?

A

At a limited rate of 10 percent per second

87
Q

Can the pilot override the inner-loop and outer-loop functions?

A

Yes, the pilot can make normal flight control inputs to override both functions.

88
Q

While hovering or in low speed flight, why is the stab programming down?

A

Eliminates undesirable nose-up attitudes caused by rotor downwash

The stabilator aligns with rotor downwash in low-speed flight.

89
Q

What is the travel range of the stabilator?

A

From 42° trailing-edge down to 10° trailing-edge up

90
Q

What does the collective position input do?

A

Decouples aircraft pitch response when collective position is changed

91
Q

What restrictions apply to stabilator travel in case of actuator failure?

A

Restricted to 35° if an actuator fails down, 30° if it fails up

92
Q

True or False: The stabilator system is completely dependent on the AFCS.

A

False

The stabilator is independent except for common sensors.

93
Q

What may be the initial indication of stabilator failure?

A

An uncommanded pitch change during accelerated or decelerated flight

This indicates that the stabilator may fail without illumination of the associated caution and aural warning tone.

94
Q

What happens if accelerated flight is continued with the stabilator in the full down position?

A

Longitudinal control will be lost

95
Q

At slow speeds, what may occur with the stabilator fixed at or near 0°?

A

Nose-high attitudes may occur

96
Q

How many channels does the SAS have?

A

Two separate and independent channels

97
Q

What are the types of SAS channels?

A
  • SAS 1 (analog system)
  • SAS 2 (digital system that is part of the AFCC)
98
Q

What occurs if SAS 2 fails?

A

The AFCC will automatically disengage the affected axis

99
Q

If SAS one fails will it automatically disengage by it`s self?

A

No the pilot needs to Manually disengage SAS 1 using the AFCS CONTROL panel

100
Q

What is the control authority of the remaining operable SAS channel after a failure?

A

Limited to ±5 percent authority, but operates at twice its normal gain

101
Q

When does the SAS caution appear?

A

Whenever SAS 1 and SAS 2 lose electrical power or when hydraulic pressure is lost to the actuators

102
Q

What is required for yaw trim disengagement above 50 KIAS?

A

Pedal microswitches and cyclic TRIM REL button must be pressed simultaneously

103
Q

Delete

What does the autopilot maintain during cruise flight?

A

Helicopter pitch and roll attitude, airspeed, heading

The autopilot also provides a coordinated turn feature at airspeeds above 50 KIAS.

104
Q

What does the AFCC do in relation to the autopilot?

A

Sends command signals to the trim actuators to reposition the flight controls

105
Q

At what airspeed is the airspeed hold engaged / with angles of banks at what?

A

Above 50 KIAS with angles of bank less than 30°

Engaging the four-way TRIM switch changes the airspeed reference at a rate of 6 KIAS per second.

106
Q

What happens when the four-way TRIM switch is actuated laterally?

A

The helicopter roll attitude changes at a rate of 6° per second

This is part of the roll attitude maintenance function.

107
Q

Delete

What does the collective/airspeed-to-yaw electrical mixing control?

A

It reduces left yaw as airspeed increases

This is controlled through the collective position sensor and an airspeed signal.

108
Q

True or False: Uninterrupted use of the four-way cyclic TRIM switch can cause a descent with altitude hold engaged.

A

True

109
Q

How does maneuvering stability increase pilot effort?

A

By displacing the cyclic forward at bank angles greater than 30°

110
Q

What is the maximum deceleration rate change during an automatic approach?

A

±1 knot per second

111
Q

What happens when the cyclic TRIM REL button is pressed in a coupled hover?

A

Removes cyclic four-way TRIM switch inputs, returning to LONG VEL and LAT VEL settings

112
Q

How is the crew hover trim grip controlled?

A

It has a control authority of ±5 KGS laterally and longitudinally.Using the HOVER TRIM CONTROL panel and cyclic four-way TRIM switch

It has a control authority of ±5 KGS laterally and longitudinally.

113
Q

What is the purpose of the automatic preflight check provided by the AFCC?

A

To check SAS components prior to flight

It is initiated using the SAS 1 pushbutton under specific conditions.

114
Q

What must be done if any of the preflight conditions change?

Flight Control System

A

Cycle the AFCC CMPTR PWR/RESET button and wait 20 seconds

This is needed before the test will initiate again.

115
Q

What does RADALT stand for?

A

Radar Altimeter

116
Q

What happens to the radar altimeter dial during a RADALT failure?

A

Declutters and displays red Xs in digital readout

117
Q

What must be done to deselect HVR after a failure?

A

HVR must be manually deselected on AFCS control panel

118
Q

What is the aircraft response when RADALT disengages?

A

BAR ALT hold engages at failure altitude; >50 KIAS - airspeed hold; <50 KIAS - attitude hold

119
Q

What remains engaged after APPR/HVR/DEPART disengages?

A

RAD ALT hold remains engaged, but is degraded

120
Q

What autopilot functions are lost after a RADALT failure?

A

All other autopilot functions lost

121
Q

Fill in the blank: The DEPART function is _______ after a RADALT failure.

A

not available

122
Q

True or False: The HVR function remains engaged after a RADALT failure.

A

True

123
Q

SAS provides stability by sensing acceleration & dampening what 3 channels?

A

Pith
Roll
Yaw

124
Q

What are the 4 sections of the flight controls?

A

Mechanical
Servos
AFCS
Tail Rotor

125
Q

How many degrees are the blade tips swept by and for what reason?

A

20 degrees, for sound attenuation & efficiency

126
Q

How many degrees is the tail rotor tilted & how much
lift in a hover does it provide?

A

20 degree tilt, 2.5 % lift

127
Q

In a tail rotor failure, what two speed provide balanced flight?

A

25 & 145 KIAS

128
Q

What do the elastomeric bearings do?

A

Allow for lead, lag, droop & flap

129
Q

Name the 18 functions of the AFCSName the 18 functions of the AFCS

A

(1)Pitch, roll, & yaw stability augmentation
(2)Stabilator control
(3)Cyclic collective & pedal trim
(4)Pitch & roll attitude hold
(5)Airspeed hold
(6)Heading hold
(7)Barometric altitude hold
(8)Radar altitude hold
(9)Pitch/Roll hover augmentation/gust alleviation
(10)Turn coordination
(11)Maneuvering stability
(12)Automatic approach to a hover
(13)Hover coupler
(14)Auto depart
(15)Crew hover
(16) Blade fold assist
(17) Automatic preflight check
(18)Diagnostics (failure advisory)

Systems (13 decks)

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