Pressurization System Overview and Design

Pressurization System Overview

• Purpose: Maintains comfortable and safe cabin altitude, regulating its rate of change.
• Areas Pressurized: Cockpit, avionics bay, cabin, and cargo hold.

System Design and Components

• Air Supply and Outflow Valve: Air from air conditioning packs pressurizes the cabin; the outflow valve controls air escaping.
• Control Mechanisms: Two Cabin Pressure Controllers (CPCs) manage outflow valve via electric motors (one active, one backup); a third motor for manual operation if both CPCs fail.
• Safety Valves: Located at the rear pressure bulkhead, prevent pressure from getting too high or low.

Pressurization Monitoring

• ECAM Cabin Pressure Page: Displays pack status, outflow valve position, active system controller, differential pressure, cabin vertical speed, and cabin altitude.
• Cruise Page: Simplifies in-flight monitoring of key parameters.

Operational Phases

• On the Ground: Outflow valve fully open; no differential pressure or vertical speed; cabin altitude matches airfield elevation.
• Takeoff: Pre-pressurization during roll; cabin altitude adjusts based on a fixed law as the aircraft climbs.
• Cruise: Cabin altitude and differential pressure stabilize; outflow valve adjusts to maintain these conditions.
• Descent: Automatic descent rate limited to ~750 ft/min; cabin pressure matches the landing field's pressure just before touchdown.
• Post-Landing: Outflow valve fully opens after touchdown to equalize pressure; automatic controller changeover prepares the system for the next flight.

Abnormal Conditions

• Landing Elevation Fault: Missing landing elevation data from the Flight Management System Guidance (FMGS); set manually using the selector.
• Safety Valve Open: A safety valve remained open for more than 1 minute; check ECAM for status (amber indication).
• Residual Pressure Control: Automatically controls the outflow valve if speed is below 100 knots or engines are shut down; or if manual mode is selected, or both CPCs fail.

Pilot Controls and Inputs

• Overhead Cabin Pressure Panel: Mode selector for auto/manual operation, landing elevation selector (normally in auto but manually adjustable), and ditching push button to seal aircraft during ditching.

• Monitoring Cabin Pressure: No manual pilot action in automatic mode; follow ECAM guidance during abnormal situations.

Key Takeaways

• The A320 pressurization system is highly automated, requiring minimal pilot intervention.
• ECAM procedures and manual controls address abnormal conditions like safety valve malfunctions or FMGS data issues.
• Passenger comfort is ensured by controlling the rate of pressure change during climb and descent.

Explore the critical components and functionalities of the aircraft pressurization system. This quiz covers air supply mechanisms, control systems, and monitoring procedures essential for maintaining cabin comfort and safety during flight. Understand the roles of valves and controllers in managing aircraft pressurization.