BELL 505 Mechanic's Guide
  • Welcome!
  • 🚁System Descriptions
    • Introduction
    • Airframe Systems
      • Dimensions and Areas
      • Fuselage
        • Forward Fuselage
        • Mid Fuselage
        • Aft Fuselage
        • Roof
        • Tailboom
      • Stabilizers
      • Landing Gear
      • Equipment/Furnishings
      • Fire Protection (Fire Extinguishing)
      • Doors
      • Windows
      • Environmental Control
        • Distribution
        • Avionics Fans
        • Heating
      • Ice and rain protection (Air intakes)
    • Integrated Avionics Systems
      • Systems Integration and Display
      • Indicating/Recording Systems
        • Instruments and Control Panels
        • General Computers
        • Central Warning System
        • Central Display System
      • Communications
      • Navigation
        • Dependent Position Determining
    • Main Rotor
      • Main Rotor Hub and Blade Assembly
      • Rotating Controls
      • Main Rotor Indicating
    • Main Rotor Drive
      • Engine/Gearbox Couplings
      • Mast Assembly
      • Transmission Assembly
      • Transmission Oil
      • Mounts and Attachments
      • Main Rotor Drive Indicating
    • Tail Rotor
      • Tail Rotor Hub and Blade Assembly
      • Rotating Controls
    • Tail Rotor Drive
      • Shafts
      • Gearbox
      • Tail Rotor Drive Indicating
    • Flight Control Systems
      • Rotor Flight Controls
        • Dual Controls Kit
        • Collective Control System
        • Cyclic Control System
        • Anti-torque Control System
        • Servo-Control System
      • Hydraulic Power
    • Fuel
      • Storage
      • Distribution
      • Fuel Indicating
    • Power Plant Systems
      • Power Plant
      • Air
      • Exhaust
      • Oil
      • Engine Control
      • Ignition
    • Electrical Systems
      • Electrical Power
        • DC Generation
        • External Power
        • DC Electrical Load Distribution
        • Multipurpose Equipment
      • Lights
  • 🪛Line Maintenance
    • Overview of Line Maintenance
    • Servicing
      • Replenishing and Depleting
        • Filling the hydraulic system with fluid
        • Draining fluid from the hydraulic system
      • Lubrication
        • Lubricating the main rotor grips
        • Lubricating the trunnion bearings
        • Lubricating the pillow block assemblies
        • Lubricating the duplex bearing
        • Lubricating the needle bearings
        • Lubricating the pitch change mechanism
        • Lubricating the crew seat positioning mechanism
      • Clean and Surface Protection
        • Rotor blade - Erosion tape replacement
        • Flushing the hydraulic system
      • Inspection
        • 50 flight hours/1 year inspection
        • 100 flight hours inspection
        • 100 flight hours/6 months inspection
        • 100 flight hours/1 year inspection
        • 100 flight hours/18 months inspection
        • 150 flight hours inspection
        • 200 flight hours inspection
        • 300 flight hours inspection
    • Test and Checks
      • Power Assurance Check (PAC)
      • Checking the fluid level of the hydraulic system
      • Flame Out Protection System (FOPS) test
      • Testing the operation of the hydraulic system
      • Testing operation of audio integration system
      • Testing operation of speech communication
      • Testing operation of central warning systems
    • Fault Isolation
      • Crew Alerting System (CAS) Messages
        • WARNING Messages
          • BATTERY HOT
        • CAUTION Messages
        • ADVISORY Messages
        • STATUS Messages
      • System Failures
    • Removal/Installation
      • Electrical Power
        • Installing the ground power unit (GPU)
        • Removing the ground power unit (GPU)
      • Equipment/Furnishings
        • Removing the crew seats
        • Installing the crew seats
      • Hydraulic Power
        • Installing the hydraulic power unit
        • Removing the hydraulic power unit
        • Replacing the HRFM filter element
        • Restoring/replacing the hydraulic pressure filter element
        • Removing the hydraulic pump
        • Removing the pump adapter assembly
        • Installing the pump adapter assembly
        • Installing the hydraulic pump
      • Main Rotor
        • Removing the NR sensor
        • Installing the NR sensor
    • Standard Repairs
      • Main Driveshaft
      • Air Intake
  • 🔧Base Maintenance
    • Overview of Base Maintenance
    • Servicing
      • Adjust, align and calibrate
      • Inspection
    • Function Test
    • Fault Isolation
    • Removal/Installation
    • Major Repairs
  • 🧰Component Interim Maintenance
    • Overview of Component Interim Maintenance
    • Time Limits
    • Component Interim Inspections
  • ⚙️Component Restoration (Overhaul)
    • General Information
    • Main Rotor Hub Assembly
      • Dimensions and Areas
      • Maintenance Planning Information
      • Tools and Workaids
      • Disassembly
      • Cleaning and Paint Removal
      • Inspections
        • Conditional Inspection
        • Non-Destructive Inspections
      • Repair
      • Finishing
      • Assembly
    • Swashplate and Support Assembly
    • Mast Assembly
    • Transmission Assembly
    • Freewheel Assembly
    • Tail Rotor Hub Assembly
    • Tail Rotor Gearbox
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On this page
  • Left servo-actuator
  • Left servo-actuator support
  • Collective servo-actuator
  • Collective servo-actuator support
  • Right servo-actuator
  • Right servo-actuator support
  • Operation
  1. System Descriptions
  2. Flight Control Systems
  3. Rotor Flight Controls

Servo-Control System

PreviousAnti-torque Control SystemNextHydraulic Power

Last updated 1 year ago

The servo control system uses hydraulic pressure from the to boost the main rotor controls, assisting the operator in moving those controls. It consists of the components that follow:

  • Left servo-actuator

  • Left servo-actuator support

  • Collective servo-actuator

  • Collective servo-actuator support

  • Right servo-actuator

  • Right servo-actuator support

The three servo-actuators and their supports are the same. A servo-actuator is an assembly made from aluminum, steel, and corrosion resistant steel parts. It consists of the cylinder, piston, valve, and rod end. The rod end has the trunnion, pin, pin pivot, and link. It is mounted at the end of the piston shaft. The valve is mounted on the piston shaft and is connected to the link. The piston slides in the cylinder with its two shafts extending from the cylinder ends. Two conduits inside the piston shaft exit inside the cylinder and apply the hydraulic pressure to either side of the piston. The end of the cylinder, near the valve, has two pins to mount it to the servo-actuator support. The servo-actuator support is made from cast aluminum and has two bushings made from corrosion resistant steel with teflon liners. The bushings are the pivot for the pins of the cylinder.

Left servo-actuator

The left servo-actuator boosts the left up-and-down motion of the , changes it to a fore-and-aft motion, and transmits it to the left boosted link.

Left servo-actuator support

The left servo-actuator support holds the left servo-actuator and the left actuator support bellcrank. It is located at the forward end of the truss assembly, on the left side, and over the cabin roof.

Collective servo-actuator

The collective servo-actuator boosts the up-and-down motion of the , changes it to a fore-and-aft motion, and transmits it to the collective boosted link. It is an assembly made from aluminum, steel, and corrosion resistant steel parts. It is mounted on the collective servo-actuator support.

Collective servo-actuator support

The collective servo-actuator support holds the collective servo-actuator and the collective actuator support bellcrank. It is located at the forward end of the truss assembly, in the center, and over the cabin roof.

Right servo-actuator

Right servo-actuator support

The right servo-actuator support holds the right servo-actuator and the right actuator support bellcrank. It is located at the forward end of the truss assembly, on the right side, and over the cabin roof.

Operation

The operation is given for one servo-actuator. The operation for the three servo-actuators is the same.

The right servo-actuator boosts the right up-and-down motion of the , changes it to a fore-and-aft motion, and transmits it to the right boosted link. It is mounted on the right servo-actuator support.

The actuator support bellcrank moves the servo-actuator trunnion forward and aft. This motion is transmitted to the link by the valve input arm pivoting on the rod end. The link controls the valve, which applies the to the piston to move it in the correct direction. The boosted motion is transmitted to the boosted link by the rod end.

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