T-45C TS, ADV & IUT ENG-17
OBOGS & ECS/Pressurization System
(2) Airborne (weight-off-wheels): with air
conditioning set to OFF, ram air valves
open, providing emergency ventilation
B.
Cockpit pressurization system
Sg 5, fr 15
(3 overlays)
1.
General
Cockpit Pressurization
System
a.
Pressurization commences with weight-off-
wheels
b.
Pressurization increases linearly until attaining
full differential pressure of 4 psi at 40,000 ft
MSL
NOTE: Cabin altitude may be as much as
2,000 ft below aircraft altitude from MSL up to
an aircraft altitude of 5,000 ft.
c.
Provides signal to CABIN ALT warning light if
cockpit altitude exceeds 24,500 +/- 500 ft MSL
2.
Pressure control valve: maintains cockpit pressure
at predetermined value with respect to aircraft
Overlay 1
altitude
Discharge Valve
Operation
3.
Discharge valves: control cockpit pressurization by
Overlay 2
adjusting airflow out of the cockpit in response to
Cockpit
control inputs from the pressure control valve
Pressurization
Overlay 3
4.
Safety relief valve: ensures that positive cockpit
Safety Valve
Operation
pressure does not exceed 4.8 psi and that inward
negative cockpit differential pressure does not
exceed 0.5 psi
C.
Avionics equipment cooling system
1.
While airborne, some of the conditioned cockpit air
exhausted through the discharge valves passes
through the avionics compartments on its way to
being discharged overboard
2.
On the ground with the canopy open, the diverter
valve directs ECS cooling air from the canopy defog
vents to the avionics compartments
Change 7 (9-98)
Page 17-17
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