TM 1-1520-238-23
Change 9
7-14.7
7.3A.
RE-BLEED PRIMARY AND/OR UTILITY HYDRAULIC SUBSYSTEMS – continued
(7) Slowly operate actuator(s) and deplete utility accumulator of hydraulic pressure (ignore nitrogen
pre-charge) and select emergency and electrical power OFF.
(8) Verify that utility manifold is empty or repeat steps 1 and 3, as applicable.
(9) Start GSU and set hydraulic pressure to 3000 + or -200 psig, but do not discharge air.
(10) Slowly operate each actuator one at a time as follows:
(a) Longitudinal – 15 cycles
(b) Collective – 15 cycles
(c) Lateral – 15 cycles
(d) Directional – 15 cycles
NOTE
To expedite utility manifold servicing, shutdown GSU and remove return hose. Install dust
cap/plug and restart GSU. Comply with item eight (8) (subsequent paragraph is an alternate
method). Leave return hose on and apply aircraft electrical power. Select rotor brake switch to
brake in conjunction with Step 8. Ensure brake is off prior to aircraft electrical power.
(11) Discharge air from utility manifold and reservice manifold to proper level (mid-screen) by operating
actuators.
(12) Set GSU pressure to zero and shutdown.
(13) Remove pressure and return hoses from utility GSE panel coupling halves. Ensure that dust caps/plugs
are secure on panel and hoses.
c. Re-bleed pylons and area weapon.
(1) Upon completion of steps 1 through 8, operate pylons and area weapon 10 cycles each. Utilize
TADS to command articulation and check utility manifold for proper fluid level (mid-green) then
comply with items nine (9) and ten (10).
d. Re-bleed aircraft hand pump.
(1) Upon completion of steps 1 through 13, repeat step 5, and decrease utility accumulator hydraulic
pressure to less than 2500 PSIG.
NOTE
The air charge in the utility manifold provides a head pressure upon reservoir fluid. This in turn
feeds the hand pump (also the transmission pump).
(2) Operate aircraft hand pump to obtain utility accumulator hydraulic pressure of 3000 psig.
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