NATOPS CH2.9 Flight Control System Flashcards Preview

Princess' MH-60R HAC Tutorial (MAY20) > NATOPS CH2.9 Flight Control System > Flashcards

Flashcards in NATOPS CH2.9 Flight Control System Deck (48)
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Into what sections can the flight control system be devided?

  • Mechanical control Section
  • Flight Control Servo Section
  • Automatic Flight Control Section


How do the mechanical control inputs get to the Swashplates?

Cyclic, collective, and trail rotor pedal inputs are routed aft and outboard of each pilot seat and vertically up the side of the aircraft (in the broom closet) where they are combinedat the overhead torque shafts inside the hyd bay

The overhead torque shafts transfer inputs from the from the trim servos and pilot controls through the pilot assist servos and mixing unit

From the mixing unit Fore/Aft/Lateral inputs are transfered to the stationary swashplate via the bridge assembly

Trim and Control Inputs -> Pilot Assist Servos -> Mixing Assembly -> Primary Servos -> Bridge Assembly -> Swashplates


How is the Tail Rotor System Actuated?

The Tail Rotor Servo is mechanically actuated (Tail Rotor Quadrant) but requires hyrdaulic pressure to operate the pitch change shaft (Tail Rotor Servo)


Describe the Primary servos

What if one fails?

Three primary servos have two stages that are indipendent and redundant.

Looking aft on the aircraft they are (from left to right think "Fat A Lady") Forward, Aft, Lateral

Should one stage become inoperative the other will pick up the slack and the approriate PRI SERVO PRESS will illuminate


Which pumps operate which stage of the Tail Rotor Servo?

The No.1 Hyd system powers the first stage TR servo, the Backup Pump will operate the second stage in the event of a leak or if the TAIL SERVO switch is placed in backup


What does the Pilot Assist Servo Assmebly contain?

Which require Hyd power?

  • Boost Servos
  • SAS Actuators
  • Hydraulic (pitch and roll) actuators

Controls are operable without hydraulic power but movements in the collective and Yaw inputs will require considerable effort. Primary servos require hydraulic pressure to operate


Name the Boost Servos and their order

There are three boost servos Collective, Yaw, and Pitch. All three plus the roll channel include SAS actuators

From left to right looking forward (think "Your Ready Plane Captain) Yaw, Roll, Pitch, Collective


Describe the Mechanical Control Compensations

  • Collective to Yaw
    • Increase in torque drives Nose right when collective is increased so TR thrust is increased
  • Collective to Lateral
    • TR Prop effect causes Helo dirft to right when collective is increase so MR disk is tilted left
  • Collective to Longitudinal
    • MR downwash on Stab pitches nose up when collective is increased so MR disk is tilted fwd
  • Yaw to Longitudial
    • TR lift vector pitches nose down with Left pedal applied so MR disk is tiled aft


Describe the electronic Control Compensation

The Camber of the trail rotor pylon varies side load with airspeed causing the nose to yaw left as airspeed increases so a portion of the trim MR torque compensation is washed out as airspeed increases

(pylon becomes more effective so less TR trim input is required)


Describe what the AFCC does and its control channels (Inner/Outer)

The Automatic Flight Control Computer commands the SAS actuators and trim actuators in all four channels. It employs two types of control the inner-loop system and the outer-loop system

The Inner-Loop system employs rate dampening (fast in response, limited in authority) it operates without flight control input. Think of this as the behind the scenes system that keeps you from over controlling

The Outer-Loop system provides long term inputs by trimming the flight controls to the position required to maintain the selected regime. This is the system that you will feel make inputs to hold alt/spd or conduct approaches


How much can the Outer-Loop move controls?

It is capable of moving the controls through the full control range, however it is limited to 10% per sec


What are the 19 functions of the Automatic Flight Control system?

  1. Automatic Preflight Check
  2. Blade-Fold Assist
  3. Cyclic, Collective, and Pedal Trim
  4. Pitch and Roll Attitude Hold
  5. Airspeed Hold
  6. Heading Hold
  7. Pitch and Roll Hover Augmentation/Gust Alleviation
  8. Turn Coordination
  9. Maneuvering Stability
  10. Radar Altitude Hold
  11. Barometric Altitude Hold
  12. Automatic Approach to a Hover
  13. Hover Coupler
  14. Crew hover
  15. Automatic Depart
  16. Pitch, Roll, and Yaw Stability Augmentation (SAS)
  17. Diagnostics (failure Advisory)
  18. Stabilator Control
  19. Cable Angle Hover


What is required to execute the preflight checks?

  1. Weight on Wheels
  2. Rotor Break On
  3. Engine Torque below 10%
  4. Both EGI attitude valid
  5. SAS 1 Push button Engaged (after AFCC on for 20 sec)


How does the AFCS contribute to the blade fold system?

The AFCS will position the cyclic, collective, and tail rotor pedals prior to the blade fold sequence


How many trim servos are there?

How much control do they have?

There are two high-torque electric servos (yaw and collective) and two hydraulic servos (pitch and roll)

They command full control authority but are rate limited to 10% per sec


How is setting pedal trim different from the others?

Below 50 KIAS pressing the trim release switches on the pedals will release the trim hold, however above 50 KIAS both the pedal trim and the cyclic trim release switches must be pressed to disengage/reengage pedal trim


When is Attitude Hold employed and what happens as you accelerate?

How much can you change attitde with the trim hat?

At airspeeds less than 50 KIAS the attitude hold feature is used. A wing leveling feature is added retrimming the aircraft as the aircraft passes through 50 KIAS

Using the trim hat you can change the pitch 5° per sec, and you can change the roll 6° per sec


When is airspeed hold used?

How much can you change the airspeed?

Airspeed hold is used above 50 KIAS and angles of bank less than 30°

Airspeed can be changed at a rate of 6 KIAS per sec


How much is heading hold slewed with the HDG TRIM switch? (Above and Below 50)

When is it reengaged?

Below 50 KIAS

Slewed 3° per sec

Above 50 KIAS

Less than a sec results in heading change, greater than a sec results in a 1° per sec coordinated turn


After a turn, it is reengaged when the following conditions are maintained for 2 sec:

  • Aircraft roll attitude is within of wings level
  • Yaw rate is less than 2° per sec


What does the Pitch & Roll Hover Augmentation and Gust Alleviation do?

Improves aircraft stability at low airspeeds bu using attitude retention, longitudinal acceleration, and leteral acceleration to eliminate drift


What does Turn coordination provide?

When is it engaged?


Turn coordination allowed the pilot to fly a coordinated turn at airspeed above 50 KIAS

It is engaged and heading hold is disengaged with roll attitude is greater than and any of the following exist:

  1. Lateral cyclic displacement is greater than 3%
  2. Cyclic TRIM REL is pressed
  3. Roll attitude exceeds 2.5° AOB using the trim hat


What does Maneuvering Stability do?

 It displaces the cyclic forward to increase pilot effort required to maintain a given pitch rate at bank angles greater than 30°

It provides 1% forward cyclic for every 1.5° AOB between 30-75° AOB


When can Radar Altimeter hold be engaged?

What happens if it fails?

It can be engaged between any altitude from 0-5000ft AGL and at any airspeed

If Radalt Hold fails, Baralt hold is automatically engaged


When may Barometric Hold be engaged?

Baralt Hold may be engaged at any altitude and airspeed


How does the AFCC deal with torque when moving the collective?

The computer monitors engine torque and will stop increasing the collective in the event that torque reaches or exceed 106% or 120% (above/below 80 KIAS)


When can you engage the Automatic Approach to a hover?

When should you not engage it?

The Auto Approach to a Hover can be engaged at any airspeed and any altitude less than 5000ft

Initiating an approach to a hover while in a trimmed turn may result in a spiraling approach that will continue through the selected altitude. Pilot action will be required to avoid water impact


What is the Auto Approach to a Hover Profile?

How much can it be altered?

  • Above Profile: 360 ft/min, Spd hold
  • Below Profile: 2.5 kt/sec, Alt hold
  • On Profile >40 KIAS: 2.5 kt/sec  215 ft/min
  • On Profile <40 KIAS: 1.5 kt/sec  130 ft/min

The deceleration can be controlled up to ±1 kt/sec, A 2 sec trim hat input will result in a full 1 kt/sec change


When will the Hover Coupler Enagage?

The Hover Coupler will engage with longitudinal groundspeed is within 1 KGS of selected speed after an automatic approach or within 5 KGS if engaged manually and when within 2 ft of the selected altitude


How much can you manipulate Ground Speed while in a hover with the Trim hat?

How fast will you climb and Descened using the POTS?

The Trim Hat will allow you to adjust longitudinal and lateral ground speed up to ±10 Knots

You can climb at 1000 ft/min and descend up to 200 ft/min


When can Crew hover be engaged and how much control authority does the creman have?

The CREW HVR pushbutton can only be activated if the hover couple mode is already engaged. 

They have control authority of ±5 KGS laterally and longitudinally