T-45C TS, ADV & IUT ENG-27/ENG-28
Engineering Review
(4) Emergency package assembly
Sg 6, fr 16
Emergency Package
(a) Automatically deploys RAT and directs
Assembly (EPA)
emergency hydraulic pressure to flight
control services when HYD 2 pressure
drops below 1500 psi
(b) Isolates sections of the HYD 2 system
from the emergency hydraulic system
when the RAT is deployed
(c) Allows resetting of the HYD 2 system
via solenoid valve with HYD 2 pressure
above 1800 psi
NOTE: The emergency package
assembly isolates the HYD 2 EDP
from the system when the RAT is
deployed. To regain HYD 2 EDP
pressure (and stow the RAT), the
HYD 2 RESET button must be
pressed.
(5) EDP bypass valve
Sg 6, fr 17
EDP Bypass Valve
(a) Reduces load on engine by bypassing
output of EDP to return side of system
during low rpm periods (engine start)
(b) Bypass in effect from 0% to 45% rpm
(c) Reset above 45% rpm (above 1800
psi) by pressing HYD 2 RESET button
(d) Bypass valve activates when engine
rpm drops below 42%, such as during
engine flameout
3.
Emergency hydraulic system: acts as a backup to
the HYD 2 system, by deploying the RAT when HYD
2 pressure falls below acceptable levels. The RAT
automatically extends whenever HYD 2 EDP
pressure falls below 1500 psi. Since the RAT is a
(9-98) Original
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