Which systems receive air from the APU through AMADs?

• A. ECS operation, MES, and GMM
• B. ECS only
• C. MES only
• D. GMM only

Answer: (A)

APU bleed air is routed through AMADs to select pneumatic systems that need air when the main engines aren’t supplying bleed air. This air feed supports three systems: the Environmental Control System, which uses bleed air to provide conditioned air for cockpit, cabin, and avionics cooling; the Mission Equipment System, which relies on bleed air for cooling and pneumatically driven components that support mission electronics; and the GMM, another system that uses bleed air for its pneumatic operations. The AMADs regulate and distribute this air to these subsystems as needed, so all three receive air from the APU through the AMADs. If you only consider one system, you’d miss the others that also rely on the same APU air path.