Air Conditioning & Pressurization System
NOTE
This is a stub page. Full system description pending ingest of FCOM Chapter 2.
Overview
The B777 air conditioning and pressurization system uses engine bleed air processed through two air conditioning packs (Left and Right) to provide conditioned air to the cabin, flight deck, and cargo compartments. The system controls cabin pressure, temperature, and ventilation.
Key Components
- Air Conditioning Packs (L, R): Convert high-temperature, high-pressure bleed air to conditioned air
- Outflow Valve: Primary cabin pressure control (automatic and manual modes)
- Safety Relief Valves: Prevent excessive cabin differential pressure
- Recirculation Fans: Supplement pack air with filtered recirculated cabin air
- Trim Air System: Fine-tunes zone temperatures
Controls & Indicators
- Overhead Panel: PACK switches, TRIM AIR switches, RECIRC FAN switches, OUTFLOW VALVE switches
- EICAS Messages:
PACK L,PACK R,CABIN ALTITUDE,CABIN ALTITUDE AUTO
Limitations
- Maximum cabin differential pressure: 9.4 psi (FCOM)
- Maximum cabin altitude: 8,000 ft (normal operations)
- Cabin altitude warning: triggers at approximately 10,000 ft