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
  • Inlet duct
  • Plenum assembly
  • Outlet duct
  • Fresh air control assembly
  • Operation
  1. System Descriptions
  2. Airframe Systems
  3. Environmental Control

Distribution

PreviousEnvironmental ControlNextAvionics Fans

Last updated 1 year ago

The distribution provides ram air ventilation to the cabin. It consists of the components that follow:

Inlet duct

The inlet duct takes outside air and directs it to the plenum. It consists of a screen and a duct made from thermoplastic resin. It is located in the nose cone assembly with the screen holding it on the intake hole from the outside.

Plenum assembly

The plenum assembly is located at the forward end of the pedestal. It consists of the plenum, damper, back cover and outlet, all made from thermoplastic resin. A spring, made from corrosion resistant steel, maintains a tension to close the damper.

The plenum assembly collects the air and directs it to the outlet duct. The damper controls the flow of air.

Outlet duct

The outlet duct is located on the top of the plenum at the forward end of the pedestal. It is made from thermoplastic resin.

The outlet duct distributes the air in the cabin.

Fresh air control assembly

The fresh air control assembly controls the position of the damper. It consists of the control knob, control bushing, control shaft, cable assembly, end fitting stud, wire plug, and clevis. It is located in the pedestal and offers easy access for the operator to control airflow in the cockpit.

Operation

The inlet duct takes ram air from the main rotor and the forward movement of the helicopter and routes it to the plenum assembly. The plenum assembly routes the air to the outlet. The air from the outlet is diffused in the cabin by the outlet duct. The fresh air control assembly positions the damper to control the flow of air.

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Inlet duct
Plenum assembly
Outlet duct
Fresh air control assembly