CONVERTING THE UH-1BI/D/H HELICOPTER HYDRAULIC SYSTEMS
FROM MIL-H-S606 TO MIL-H-U83282 HYDRAULIC FLUID
C-1. Ground Servicing Equipment Required.
a. Hydraulic Ground Service Unit, P/N NSU-1 or D-5.
C-2. Items to be Manufactured.
a. Drain line from ground test coupling (return) on aircraft.
C-3. Removal of Components.
a. Disconnect all lines to the hydraulic pump and allow lines to drain.
Plug all lines after draining, disconnect and remove the hydraulic pump from the aircraft.
b. Remove the filter element from the hydraulic module and allow module to drain. Clean and reinstall the filter
bowl without the filter element.
C-4. Component Flushing.
a. To flush hydraulic fluid from the hydraulic pump, turn the splined shaft by hand while pump is inverted until
fluid no longer drains from the pressure and return ports in the pump. Fill pump through return port with MIL-H-83282
and repeat the above procedure.
b. Disconnect all hydraulic lines to the main rotor servos at the servo cylinders. Drain all lines.
c. Disconnect all hydraulic lines to the tail rotor servo at the servo cylinder. Drain all lines. Disconnect the tail
rotor servo cylinder at the control tube and actuate the piston four full strokes to discharge residual fluid from the
d. Disconnect lines to ground test couplings, (both sides of the firewall) drain lines and reconnect lines to the
C-5. Component Replacement.
a. Install hydraulic pump. Fill pump with MIL-H-83282 hydraulic fluid through the case drain port and reconnect
all hydraulic lines to the pump.
b. Install pressure and return lines to the main rotor servo cylinders.
Do not interconnect hydraulic hoses from one cylinder to the other.
c. Install pressure and return lines to the tail rotor servo cylinder and reconnect the control rod to the piston.