FLT Controls & Hydraulics Flashcards by Tyler Elliot

What are the main components for the primary flight controls?

Cyclic/Collective Servoactuators, Cyclic/Collective Mixer Assembly, Main Rotor Swashplate, Directional Servoactuator, Tail Rotor Swashplate, Stabilator

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What are the five Flight Control Systems?

Collective
Cyclic
Upper 
Directional
Stabilator

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What control system receive and combine control inputs from the collective and cyclic control sticks for vertical, longitudinal, and lateral flight?

Upper Flight Control System

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What assembly receives control inputs from the two lateral links and the torque link and transmits these control inputs to the main rotor?

Swashplate assembly

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What assembly transmits rotational power to the rotating Swashplate from the main rotor head?

Scissors Assembly

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Stabilator movement is provided by two tandem linear __________ actuators mounted back to back.

Electrical

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The primary hydraulic system provides hydraulic power to the _______, ________, and ________ control servo actuators

Collective, Cyclic, and Directional

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The Utility Hydraulic System provides _________ hydraulic power to the servo actuators and _________________________.

Redundant

Utility hydraulic system components

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The _______________ will provide emergency hydraulic power to the servo actuators, should both the primary and utility hydraulic systems fail.

Utility Accumulator

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The _____________ is used to optimize the pitch angle of the airframe at various air speeds.

Stabilator Control System

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The stabilator improves longitudinal handling characteristics and ______________ of the helicopter for improved ___________________.

Forward visibility

Flight-crew effectiveness

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What positions the stabilator?

Stabilator actuator

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What are the degree ranges the stabilator can articulate in the auto mode?

-5 degrees trailing edge up to +25 degrees trailing edge down

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If aircraft exceeds ____ KTAS, the aircraft will revert the horizontal stabilator to the auto-mode.

80 KTAS

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What are the degree ranges the stabilator can articulate in the manual mode?

-10 degrees trailing edge up to +35 trailing edge down

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The stabilator icon is displayed in white _______.
The icon is yellow if ________.
The icon is red if ________.

Manual mode is selected and normal flight
Stabilator is detected as failed
Nominal airspeed is exceeded

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The FMC release switch disengages the ______________.

Stability Command Augmentation System (SCAS)

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Although Prohibited unless in a failed or partial failed mode, what MPD page allows the crew member to turn off the force trim?

A/C UTIL –> FMC TRIM

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The ___ controls are the only controls with the force trim spring attached. The ____ has the same feel because his controls are connected to the _____.

PLT has spring
CPG does not have spring
PLT

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Pressing the force trim button on the cyclic (up) allows what?

force trim momentarily to disengage (magnetic spring)

- stability augmentation system (SAS) actuators to reset

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The Flight Management Computer (FMC) commands the position of the flight control actuators based on what inputs?

Crew station LVDTs, ARDDs, EGI, HADS, radar altimeter, and pressure sensors

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The FMC has software logic which provides for
1-
2-
3-
4-

1- Attitude Hold
2- Altitude Hold
3- Automatic Stabilator Control
4- Stability Command Augmentation Subsystem (SCAS)

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What forms of attitude hold does the FMC provide?

Attitude, Velocity, Position, Heading

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What are the two types of altitude hold?

Radar and Barometric

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Controlled by the FMC, the SCAS has three functions:

Stability Augmentation System (SAS), Command augmentation System (CAS), and the Hold Modes

What are the outputs of the Stability Augmentation System?

Rate Damping Turn Coordination Atmospheric Upset Damping

When is SCAS automatically engaged?

Following EGI alignment

The SAS provides rate damping and turn coordination at air speeds greater than ___ KTAS. It also dampens external forces (wind gusts) to the airframe to stabilize the helicopter.

40 KTAS

What is the SAS authority in each of the servos?

All 10% except Longitudinal FWD (20%)

Approx how long does it take to reset the SAS ability on the Servoactuator when it is saturated?

3 sec of holding down force trim

__________ is defined as an increased response to the flight control movement. The _____ provides a uniform aircraft response for a given control input at all air speeds.

Command Augmentation System (CAS) | CAS

Attitude hold is active (accelerating) from _________. | Decelerating, it will not turn off until below ______.

40 KTAS - Vne | 30 KTAS

Position Hold is designed to ________________.

Hold the aircraft over a given position on the ground

Below ______, the position hold uses pitch and roll SCAS to maintain a precise position over a selected geographic location.

5 knots ground speed

Velocity hold is active from __________ ground speed, depending on whether the aircraft is accelerating or (decelerating).

5 - 40(30)

Altitude hold is provided thought the _____ SCAS

Collective

When will Radar altitude hold be engaged?

EGI ground speed is less than 40 knots and radar alt less than 1428'

When will ALT Hold disengage?

Collective displaced > 0.5 inch 97% > Nr > 104% Either ENG exceeds 100% TQ Either ENG exceeds 867*C

_____ is an emergency fly by wire __________________ which permits continued control of the aircraft in the event of jammed or severed mechanical controls in any of the 4 axis.

BUCS | Backup Control System

What are the two reasons for which BUCS will be engaged?

1- FMC senses a mistrack between LVDT inputs and servo RAM LVDT outputs 2- If a jam has occurred and the crew member decouples an ARDDS

If there is only a mistrack between the PLT and CPG LVDT, what will occur?

BUCS FAIL

If the flight controls are severed, the FMC will engage BUCS after sensing _______________.

A mistrack between the flight control LVDTs and the servo RAM LVDTs

The primary side of the Servo-actuator has an _______________ that allows the FMC to affect the flight controls.

Electro-Hydraulic Valve (EHV)

What does failure of the primary hydraulic system result in the loss of?

FMC SCAS (SCAS, SAS, and BUCS)

If the ____________, the ___________ shutoff valve will close, isolating the directional Servoactuator from the utility hydraulic system. In this condition, the _____________ cannot provide emergency hydraulic power to the directional Servoactuator when EMER HYD is selected; the tail rotor will remain fixed pitch.

Utility Hydraulic fluid level is low Low-Level Utility Accumulator

The _______________ is a potentiometer that translates control motion into an electrical signal that is utilized by the FMC to provide SCAS, SAS, BUCS, and hold mode functions.

Linear Variable Differential Transducer (LVDT)

The ______ provides the means to physically disconnect a crew station flight control from it's associated linkage and is located by each flight control. The _______ senses when this decoupling occurs.

ARDD | Rotary Variable Differential Transducer (RVDT) - consistently monitored by the FMC

During BUCS operation the mechanical spool is locked out, giving the SAS sleeve ____ authority.

100%

Describe the BUCS sequence: JAMMED CONTROL AXIS

1- crew member rolls ARDD 2- RVDT informs FMC that ARDD is decoupled 3- Full control via BUCS is assumed after 3 seconds "easy on"

Describe the BUCS sequence: JAM IN CPG STICK

1- CPG stick jammed above ARDD, cannot roll it 2- PLT rolls ARDD 3- RVDT informs FMC of rolled ARDD 4- PLT LVDT commands system and full control after 3 seconds

Describe the BUCS sequence: JAM BETWEEN/AFT of CREWSTATIONS

1- decouple the ARDD 2- BUCS engaged upon RVDT informing the FMC 3- 3 seconds easy on for whomever decoupled

Describe the BUCS sequence: SEVERED CONTROL AXIS

PLT LVDT mistrack with RAM A actuator LVDT and CPG to RAM B LVDT. FMC engages BUCS

Describe the BUCS sequence: SEVERANCE BETWEEN THE CREWSTATIONS

CPG controls move freely and there is a mistrack reported to the FMC. BUCS FAIL as the PLT's controls are correct according to FMC. CPG locked out, unless BUCS trigger is used (PLT incapable of flying)

Describe the BUCS sequence: SEVERANCE OF BOTH CREWSTATIONS

PLT and CPG are free to move to mech stop. Mistrack between LVDT and servo are detected by FMC. BUCS on in 1 sec

If the PLT decouples his ARDD first he has flight controls through his LVDTs. The CPG can obtain control by __________________.

Decoupling his ARDD and pressing the BUCS trigger

If the CPG decouples first he has flight controls through his LVDTs. The PLT can obtain control by _________________.

Decoupling his ARDD

If a severance mistrack occurs with both sticks mistracking both RAM LVDTs, the PLT LVDTs have control. __________________________.

ARDD/RVDT signals are ignored. The CPG can gain control by pressing his BUCS trigger.

If the CPG activates BUCS through his trigger, BUCS engages under CPG LVDT control if a stick mistrack occurs and ARDD/RVDT signals ______________.

Are ignored

How can the crew members attempt to reset a BUCS FAIL?

Toggling the appropriate SAS channel on the A/C UTIL page

What is the only way to exit BUCS?

Successful completion of an IBIT

While in BUCS, ______ functions are not available in that axis.

SCAS

[WARNING] - When BUCS is engaged do not release the flight controls until ________________________. _____________ May or May not be engaged.

The flight has been completed and the main rotor has come to a complete stop. Force trim

How can crew members attempt to reset faults found from Flight Control BITs?

Toggling the SCAS switches on the A/C UTIL page

Flight control IBIT (BUCS test) may not run correctly when using ________________.

AGPU. Some carts don't work well

What is happening when the aircraft "thumps" when running a BUCS test (FLT CNTRL IBIT)?

FMC is testing the full authority of the SAS

[CAUTION] - FMC DISENGAGED | What occurred?

FMC has disengaged in one or more axis

[CAUTION] - FMC FAIL | What occurred?

AC power is available > 3 sec when FMC failed

[CAUTION] - AUTO/MAN STAB FAIL | what occurred?

SP detects a failure in both AUTO and MAN stabilator modes

[CAUTION] - MAG FORCE TRIM OFF | What occurred?

Magnetic force trim is detected as OFF

[CAUTION] - BUCS ON BUCS ON (PLT/CPG) (AXIS) What occurred?

The BUCS is engaged in unknown axis Or Engaged in specified axis

[CAUTION] - BUCS FAIL | What occurred?

The BUCS has failed in unknown or specified axis

[CAUTION] - HOVER DRIFT | What occurred?

Hover drift of greater than 48 feet detected (one rotor disc)

What are the two halves of the flight control servoactuators? Which half supports FMC? Which supports EMER HYD?

Primary and Utility PRI - FMC UTIL - EMER HYD

What components are supported by the UTILITY HYD System?

``` Tail wheel lock actuator Rotor break APU starting motor (accumulator) Weapon System Components Emergency Hydraulic Pressure ```

What servoactuators are driven by the PRI HYD System?

Collective / Lateral / Longitudinal | Directional

Only the PRI side of the servos has an Electro-Hydraulic Valve that allows ___________________ to affect flight controls. Failure in the PRI results in a loss of these functions.

FMC and BUCS

Approx what is the quantity of Hydraulic Fluid in the PRI HYD system?

3 quarts

[CAUTION] - Do NOT place the rotor brake in _____ with the rotors turning.

LOCK

The Primary Hydraulic Pump draws low-pressure fluid from the ____________ and provides pressurized (_____ psi) fluid to the _______________.

Primary Hydraulic Reservoir 3000 psi Primary Hydraulic Manifold

What drives the PRI HYD pump?

Main XMSN Accessory Gearbox (AGB)

What is the flow rate of the PRI HYD Pump?

Up to 6 gallons per min

The ____________ stores, filters, supplies, and regulates hydraulic fluid for the PRI HYD System.

Primary Hydraulic Manifold

What does the PRI HYD Reservoir do?

Stores low-pressure fluid for system use

The PRI/UTIL HYD Reservoir fluid capacity is __ pint. The fluid is pressurized by IPAS air to 31 +/- 3 psi to prevent _______________.

1 pint | Prevent pump cavitation and fluid foaming

FLT Controls & Hydraulics Flashcards

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