TB 1-1520-238-20-116
(8) Apply external power to aircraft in accordance with the TM 1-1520-238-23 series manuals and
the AH-64D Interactive Electronic Technical Manual (IETM).
(9) Visually inspect the 7-311120609 pivot spacers in accordance with the TM 1-1520-238-23,
paragraph 1.70 or TM 1--1520--Longbow/Apache (IETM).
(10) Recheck AGPU reservoir fill level gauge on hydraulic control panel to verify that reservoir
is full. Add fluid, as required.
(11) Open AGPU dual hydraulic service manifolddrain valve, and drain utility manifold reservoir
(approximately one gallon).
(12) In pilot/copilot gunners station, set emergency hydraulics switch to ON, and on AH--64D, set
MFD to ENG--SYS.
(13) Move pilot's cyclic in small circular motion to deplete hydraulic fluid from emergency system.
CAUTION
Large cyclic movements may activate the Automatic Roller Detent
Decoupler (ARDDS) on the AH--64D or shear pins on the Shear Pin
Activated Decoupler (SPAD) on the AH--64A.
(14) When utility accumulator is depleted, set emergency hydraulics switch to OFF (approximate-
ly one gallon hydraulic fluid flushed).
(15) Set reservoir lever to AGPU, and on AGPU hydraulic control panel, set return/bypass lever
to OFF.
(16) Set hydraulic power switch to ON, and turn pressure relief valve to MAXIMUM (clockwise).
(17) Set AGPU hydraulic pressure by placing pressure switch to INCREASE position until pres-
sure reaches 3300 psig, as shown on pressure gauge.
(18) Turn AGPU pressure relief valve counterclockwise until gauge pressure drops slightly; then
tighten lock nut.
(19) Set AGPU pressure switch to DECREASE until pressure gauge reads 3000 psig.
(20) Set AGPU hydraulic output switch to ON.
NOTE
The Auxilliary Ground Power Unit (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 to 7 gallons flushed).
CAUTION
To avoid extensive damage to the Auxilliary Ground Power Unit
(AGPU) do not allow the AGPU reservoir to become empty.
(21) While monitoring AGPU fluid, cycle flight controls (cyclic, collective, and pedals) five cycles
each in accordance with hydraulic system bleed procedures in TM 1--1520--238--23, paragraph 1.35.ab. or
TM 1--1520--Longbow/Apache (IETM).
(22) Shut off AGPU dual manifold to drain port.
(23) Cycle flight controls two additional cycles.
(24) Flushing is now complete.
(25) If required, perform bleed in accordance with TM 1--1520--238--23, paragraph 1.35, or TM
1--1520--Longbow/Apache (IETM).
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