Sources
Compressed air may come from engine bleed stages, the APU or an external ground source. Modern aircraft may use different architectures, including more-electric designs.
Control
Valves and control systems regulate pressure, temperature and source selection. Pre-cooling may be used before distribution.
Users
Common users include air conditioning, engine starting, anti-ice and pressurization-related functions, depending on aircraft design.
Maintenance context
Understand the normal flow path and isolation logic. Use approved data for leak checks, overheat troubleshooting and operational limits.
