TM 1-1520-238-23
Change 9
7-14.1
7.2.
HYDRAULIC SYSTEM LEAK CHECK – continued
(9) Recheck AGPU reservoir fill level gauge on hydraulic control panel to ensure reservoir is full. Add fluid if
necessary.
(10) Open AGPU dual hydraulic service manifold drain valve and drain utility manifold reservoir (approximately
one (1) gallon).
(11) In pilot’s station, set emergency hydraulics switch to ON. On AH-64D, set MFD to ENG-SYS.
(12) Move pilot’s cyclic in small circular motion to deplete fluid from emergency system.
CAUTION
Large cyclic movements may activate the ARDDS (AH-64D) or shear pins on SPADS (AH-64A).
(13) When utility accumulator is depleted, set emergency hydraulics switch to OFF (approximately one (1)
gallon fluid flushed).
(14) On AGPU hydraulic control panel, set return/bypass lever to OFF. Make sure reservoir lever is set to
AGPU.
(15) Set hydraulic power switch to ON. Turn pressure relief valve to maximum (clockwise).
(16) Set AGPU hydraulic pressure by placing pressure switch to INCREASE position until pressure reaches
3300 PSIG, as indicated on pressure gauge.
(17) Turn AGPU pressure relief valve counterclockwise until gauge pressure drops slightly; and tighten lock nut.
(18) Set AGPU pressure switch to DECREASE until pressure gauge reads 3000 PSIG.
(19) Set AGPU hydraulic output switch to ON.
NOTE
The AGPU fluid level will decrease to between 1/2 and 1/3 full on the reservoir level gauge. Do not
allow the reservoir level to decrease below 1/3 full (5-7 gallons flushed).
CAUTION
To avoid extensive damage to the AGPU, do not allow the AGPU reservoir to empty.
(20) While monitoring AGPU fluid, cycle flight controls (cyclic, collective, and pedals) five (5) cycles each in
accordance with hydraulic system bleed procedures in TM 1-1520-238-23, paragraph 1.35ab., or TM
1-1520-Longbow/Apache (IETM).
(21) Shut off AGPU dual manifold drain port.
(22) Cycle controls two additional cycles.
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