AFCS (in progress)

Question 1

The central component of the AFCS is ______

Answer 1

the digital advanced flight control computer (AFCC)

Question 2

The _____ is designed to select the source of the single phase, 115 VAC, phase B power to be applied to the AFCC.

Answer 2

Voltage Sensor Relay (VSR)

Question 3

Normally, the AFCC is powered by the _____,with the VSR energized and the _____ bus relay energized.

Answer 3

#1 AC Primary Bus
AC Essential

Question 4

If voltage is not within tolerance, the VSR deenergizes and the ____ and _____ are powered from the _____.

Answer 4

AC Essential bus and AFCC

No. 2 AC Primary Bus

Question 5

The stabilator is an ______________ control system with a backup manual slew control

Answer 5

automatic, fly-by-wire

Question 6

In low speed flight, the purpose of the stabilator’s variable angle of incidence functionality is to ____________ caused by rotor downwash impinging on the stabilator. To accomplish this, the stab was designed to program so it aligns with rotor downwash in low-speed flight regimes.

Answer 6

eliminate undesirable nose-up attitudes

Question 7

The Stabilator TEST pushbutton is operational below ____ KIAS and is used to check the ______

Answer 7

50, automaticmode fault detector

Question 8

Two _________, acting in series, position the stabilator.

Answer 8

electric jackscrew actuators

Question 9

Below ____ KIAS, the stabilator will be 42 degrees trailing edge down.

Answer 9

30

Question 10

The stabilator electrical screw actuators receive power from the ____ and _____.

Answer 10

dc essential bus and NO. 1 DC primary bus

Question 11

Four inputs are required to position the stab:

Answer 11

Collective position, lateral acceleration, airspeed, pitch rate

Question 12

Collective to Yaw (control mixing)

Answer 12

Cause: Main rotor torque

Compensation requirement: Nose yaws right when collective is increased

Compensation: Tail rotor thrust is increased

Question 13

Collective to Lateral (control mixing)

Answer 13

Cause: Lateral lead (tail rotor propeller effect)

Compensation requirement: Helicopter drifts right when collective is increased

Compensation: Rotor disc is tilted left

Question 14

Collective to longitudinal (control mixing)

Answer 14

Cause: Rotor downwash on stabilator

Compensation requirement: Nose pitches up and helicopter drifts aft when collective is increased

Compensation: Rotor disc is tilted forward

Question 15

Yaw to longitudinal (control mixing)

Answer 15

Cause: Tail rotor lift vector

Compensation requirement: Nose pitches down and helicopter drifts forward when left pedal is applied

Compensation: Rotor disc is tilted aft

Question 16

Collective/airspeed to yaw (control mixing)

Answer 16

Cause: Camber of tail rotor pylon varies side load with airspeed

Compensation requirement: Nose yaws left as airspeed increases

Compensation: A portion of the main rotor torque compensation is provided by a trim input that is proportional to collective position and airspeed. The trim input is then progressively washed out as pylon side loads increase with airspeed.

Question 17

The AFCS is composed of three major subsystems:

Answer 17

the Stability Augmentation System (SAS), the stabilator system, and the Advanced Flight Control Computer (AFCC)

Question 18

The AFCC processes incoming information from various sensors and stores the information in its memory. The data is used by the computer’s central processing unit to compute required correction signals. Inner-loop correction signals are routed to the _______ and outer-loop signals are routed to the________.

Answer 18

SAS actuators, trim actuators

Question 19

The AFCC is powered by the ______. If the voltage is not within tolerance, _________________.

Answer 19

No. 1 AC Primary bus, the VSR deenergizes and the AC Essential bus and AFCC are powered from the No. 2 AC Primary bus.

Question 20

SAS provides improved stability by ____________.

Answer 20

sensing acceleration rate in the pitch, roll, and yaw axes and applying a control input to dampen out the sensed rate.

Question 21

SAS 1 is an ________; SAS 2 is a ______ that is part of the _____.

Answer 21

analog system, digital system, AFCC

Question 22

With both SAS channels engaged, the pitch, roll, and yaw actuators have _______________.

Answer 22

±10 percent control authority with each channel providing ±5 percent

Question 23

Only SAS 2 commands the collective inner-loop actuator (CILA). The collective SAS operates with ______________ modes engaged and is limited to ±10 percent control authority.

Answer 23

RAD ALT, BAR ALT, APPR/HVR, and DEPART

Question 24

For each control axis (except vertical), command signals from both SAS channels are applied simultaneously to___________. The two signals are summed to provide a single input into the flight control system through a ___________.

Answer 24

separate coils of an electrohydraulic servo valve; single-series SAS actuator

Question 25

If ____ has failed, the AFCC will automatically disengage the affected axis. If ____ has failed, the pilot must manually disengage SAS 1 using the AFCS CONTROL panel. The remaining operable SAS channel is limited to ±5 percent authority, but operates at twice its normal gain to partially compensate for the failed SAS channel.

Answer 25

SAS 2, SAS 1

Question 26

The trim system uses _____ servos for the yaw and collective axes and _____for the pitch and roll axes.

Answer 26

two high-torque electric; two hydraulic servos