T-45C TS, ADV & IUT ENG-09
Hydraulic System
IV. Emergency hydraulic system:
Sg 4, fr 2
Lesson Organization
A.
Description: the emergency hydraulic system acts as a
backup to the HYD 2 system, by deploying the RAT
HYDRAULIC SYSTEM
when HYD 2 pressure falls below acceptable levels.
* T-45C hydraulic system overview
The RAT automatically extends whenever HYD 2 EDP
* Hydraulic system no. 1 (HYD 1)
pressure falls below 1500 psi. Since the RAT is a fixed
* Hydraulic system no. 2 (HYD 2)
displacement pump, emergency hydraulic pressure will
* Emergency hydraulic
fluctuate between 2500 and 3000 psi displayed on the
system
HYD 2 gauge, whenever the RAT is in operation
* Aircraft interfaces
Sg 4, fr 3, p 1
B.
Emergency hydraulic system components
Hydraulic System
Block Diagram
1.
RAT
(3 overlays)
a.
Location: RAT bay, aft fuselage behind gravity
filler cap, forward of tail section
b.
Functional: produces hydraulic pressure for
emergency hydraulic system in event of HYD 2
EDP pressure loss.
Overlay 1
Ram Air Turbine
c.
Physical
(RAT)
(1) Consists of a variable pitch turbine, speed
sensor, and fixed displacement hydraulic
pump
NOTE: The RAT utilizes HYD 2 reservoir
fluid to provide power for the emergency
hydraulic system.
(2) Mounted on hinged support leg
(3) Raised into airstream automatically
by hydraulic actuator when HYD 2 EDP
pressure drops below 1500 psi
(4) Output volume and pressure vary
with pump speed (fixed displacement
pump)
(5) Speed limited by internal governor to 7300
rpm
(9-98) Change 1
Page 9-28
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