T-45C TS, ADV & IUT ENG-09
Hydraulic System
LESSON NOTES
Explain that although the HYD 2 caution light extinguishes at
2000 psi, it may be illuminated with well over 2000 psi showing
on the HYD 2 pressure gauge. This is because the gauge is
indicating emergency hydraulic system pressure, from RAT
output; however, both HYD caution lights indicate EDP output.
The HYD FAIL warning light, unlike the caution lights, indicates
low EDP pressure in both systems as well as low emergency
hydraulic system pressure.
2.
HYD 2 pressure falls below 1500 psi
Overlay 1
a.
If HYD 2 pressure drops below 1500 psi,
emergency package assembly in conjunction
with the RAT accumulator deploys the RAT
NOTE: Should the HYD 2 light not be
illuminated with the RAT light on, the HYD 2
lamp may be burned out. This failure can be
confirmed by placing the MASTER TEST switch
to LAMP.
b.
If no leak in HYD 2, RAT will supply hydraulic
backup pressure for HYD 2 services (ailerons
and stabilator)
c.
Regardless of RAT status, HYD 1 is providing
primary power for the flight controls
F.
HYD 2 operational characteristics summary 1.4.8.2.1
HYD 2 is an independent hydraulic system used to power
the flight control. The Emergency Hydraulic System
provides HYD 2 redundancy when HYD 2 EDP pressure
falls to approximately 1500 psi, regardless of the HYD 1
status. Landing approaches on RAT hydraulic power
alone should not be attempted.
(9-98) Original
Page 9-27
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