STUDENT GUIDE FOR T-1A AIRCRAFT SYSTEMS
Cabin pressurization and control
Environmental system (Air Cycle Unit (ACU))
704. PNEUMATIC DISTRIBUTION SYSTEM
The pneumatic distribution system consists of ducts, valves, ejectors, fittings, and tubing. When
the engine is operating, conditioned bleed air is supplied through pressure regulators and shutoff
The engine and wing anti-icing systems
Pressurizing and air conditioning the aircraft
Pressurizing the hydraulic reservoir
Bleed air is also used to inflate the entrance door seal.
Pressure Regulator / Shutoff Valves
The pressure regulator shutoff valves are controlled by a switch placarded BLEED AIR located
on the environmental control panel. These valves are normally open and regulate bleed air
pressure to the ACU for air conditioning.
The pressure regulator regulates air pressure to the entrance door inflatable seal, ejector, air
conditioning temperature control system, and the hydraulics reservoir. The regulator is preset to
adjust bleed air pressure to 15 + 1 psi.
Check valves are installed in the bleed air system inlet lines to prevent bleed air from one engine
entering the bleed air lines of the other engine. When operating on a single engine, the check
valve will prevent bleed air from escaping through the inoperative engine.
705. AIR CONDITIONING SYSTEM
The air conditioning system provides temperature controlled, pressure-regulated heating and
cooling air, ventilation, and cabin and flight deck pressurization. The system also provides
cooling air to the avionics rack. The air conditioning system consists of the following
Vapor Cycle Cooling Subsystem (VCCS)
7-2 ENVIRONMENTAL CONTROL SYSTEMS