**ATA Chapter 21-12 - Air Conditioning - Distribution** This subchapter covers the **air distribution system** within the aircraft's air conditioning system. It focuses on how conditioned air is routed, managed, and delivered throughout the cabin, cockpit, cargo compartments, and avionics bays. ### **Key Components:** 1. **Main Air Distribution Ducts:** - Large ducts that transport conditioned air from air conditioning packs to different zones in the aircraft. 2. **Zonal Distribution:** - Systems that divide the aircraft into zones (e.g., cockpit, passenger cabin sections, cargo areas) with individual temperature control. 3. **Diffusers and Vents:** - Outlets like ceiling diffusers, overhead vents, and floor grills for even air distribution. 4. **Mixing Manifolds:** - Devices that blend air from different sources (recirculated and fresh air) to maintain consistent temperature and pressure. 5. **Cabin Recirculation Fans:** - Fans that recirculate air within the cabin to improve airflow efficiency and reduce energy consumption. 6. **Control Valves and Dampers:** - Devices regulating airflow by opening or closing ducts as needed for temperature control and pressurization. 7. **Smoke and Fire Isolation Features:** - Safety mechanisms to isolate air distribution in case of smoke or fire detection. ### **Purpose:** The air distribution system ensures that conditioned air is evenly delivered throughout the aircraft, maintaining passenger comfort, crew efficiency, and proper environmental conditions for sensitive equipment. It works alongside temperature and pressure control systems for optimal cabin conditions.

Sub-chapters

Rotable Parts

Part Number	Description	OEM
66-8388-3	SPIRNG LINK ASSY	BOEING B707
66-8388-5	SPRING LINK ASSY	BOEING B707
66-8388-7	SPRING LINK ASSY	BOEING B707