TM 1-1520-238-23
1-106
Change 6
1.35.
HYDRAULIC SYSTEM BLEED
1.35.1. Description
This task covers:
System Bleed.
1.35.2. Initial Setup
Tools:
Aircraft mechanic’s tool kit (item 376, App H)
Aircraft maintenance tool kit (item 373, App H)
Light duty laboratory apron (item 27, App H)
11/16 x 3/8-inch drive open end box socket wrench
crowfoot attachment (item 70, App H)
Industrial faceshield (item 129, App H)
Chemical protective gloves (item 154, App H)
14-quart utility pail (item 222, App H)
Aircraft power unit (item 232, App H)
Hydraulic brake bleeder tube (item 399, App H)
0 - 600 inch-pound 3/8-inch drive dial indicator torque
wrench (item 447, App H)
Hydraulic pressure “Y” hose (figure D-466, App D)
Hydraulic return “Y” hose (figure D-469, App D)
Personnel Required:
67R
Attack Helicopter Repairer
One person to assist
68X
Armament/Electrical System Repairer
67R3F
Attack Helicopter Repairer/Technical
Inspector
References:
TM 1-1270-476-20
TM 1-1520-238-T
TM 9-1090-208-23
TM 55-1730-229-12
Equipment Conditions:
Ref
Condition
1.57
Helicopter safed
2.2
Access fairing L175 removed; doors T250L,
T250R, T290L, T290R, L325, and R325
opened
1.36
Utility hydraulic accumulator serviced with
nitrogen
1.37
Utility hydraulic return accumulator serviced
with nitrogen
7.3
Primary hydraulic system vented
7.57
Utility hydraulic system vented
1.70
External power – electrical applied
NOTE
This procedure is required following replacement of any hydraulic system component. It is also
recommended as an air purge to the hydraulic system if the hydraulic system or a component such
as flight control actuators have trapped air.
The procedure starts with an initial AGPU powered bleed which removes the majority of air from the
hydraulic systems. An APU run purges the primary and utility hydraulic pumps, APU start motor, and
return lines. A final AGPU bleed removes any air that may have pushed into the hydraulic system
during the APU run.
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