TM 1-1520-238-23
7-14.6
Change 9
7.3A.
RE-BLEED PRIMARY AND/OR UTILITY HYDRAULIC SUBSYSTEMS
7.3A.1. Description
This task covers:
Re-bleed Primary and/or Utility Hydraulic Subystems.
7.3A.2. Initial Setup
Tools:
Aircraft mechanic’s tool kit (item 376, App H)
Personnel Required:
67R
Attack Helicopter Repairer
Equipment Conditions:
Ref
Condition
1.57
Helicopter safed
2.2
Access door L190 opened
7.3A.3. Re-bleed Primary and/or Utility Hydraulic Subsystems
a. Check for repetitive discrepancies.
(1) Fluctuating hydraulic pumps
(2) Leaking actuators
(3) DASW BUCS
(4) Ratchety or sluggish operation
(5) Aircraft hand pump operation
b. Bleeding and Re-bleeding Instructions.
NOTE
If both primary and utility subsystems require re-bleeding, shop “Y” hoses must be used to
expedite tasks. The hoses can be locally manufactured per drawings in Appendix D, Figures
D-446 and D-467.
(1) Utility manifold must have air charge (30 + or -5 PSIG) available. Do not discharge air.
(2) Position and connect ground services unit (GSU) hoses to return and pressure coupling halves on utility
ground support equipment (GSE) panel. Allow manifold to empty or comply with step 3 below. Do not
discharge air.
(3) Verify that hand pump selector valve is facing AFT and aircraft is clear for external hydraulic power.
(4) With manifold completely empty, start GPU and set pressure to 3000 + or -200 psig. Do not discharge
air. If required, service manifold using additional air to deplete fluid.
(5) Return GSU pressure to 0 and shut down.
(6) Verify that aircraft is clear for electric (battery or external power) power, and engage emergency
hydraulics.
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