Rockwell Commander 112 - HYDRAULIC POWER PACK

ROCKWELL
COMMANDER
112/B/TC/TCA
MAINTENANCE MANUAL
SECTION III
HYDRAULICS
REMOVAL
a. Jack aircraft as outlined in Section II.
b. Disconnect hydraulic lines from actuating
cylinders and plug or cap open lines and fittings to
prevent contamination.
c. Remove attaching bolts from cylinder and
landing gear.
NOTE
Do not disturb the setting of the rod end
on the shaft.
d. Remove actuating cylinder.
MODEL 112 (Serial numbers thru 380). DISASSEMBLY
AND REPAIR. Disassembly procedures apply to both
main and nose gear actuating cylinders. Repair is
limited to cleaning and inspection of the parts and re-
placement of worn or damaged parts and a-rings.
a. Loosen setscrew s and remove end caps and
end plugs (see Figure 3-4).
b. Withdraw shaft and piston from actuator housing.
c. Remove detent cylinder valve body.
d.
Remove snap ring, cover plate, spring and de-
tent from detent cylinder valve body.
e. Remove and discard aU a-rings.
f. Inspect and clean all parts in dry cleaning solvent
and dry thoroughly.
g. Inspect all internal parts and cylinder bore for
\vear and damage. Replace worn or damaged parts.
h. Wipe new a-rings with MIL-H-5606 hydraulic
fluid prior to installation in actuator housing.
i. When reassembling cylinders, install detent
cylinder valve body after shaft and piston has been
installed.
MODEL 112 (Serial numbers 381 and subsequent).
MODELS 112B/TC/TCA. Disassembly procedures
apply to both main and nose gear actuating cylinders.
Repair is limited to cleaning and inspection of the
parts and replacement of worn or damaged parts
and 0- rings.
a. Loosen setscrews and remove end caps and
end plugs (see Figure 3-4).
b. Withdraw shaft and piston from actuator housing.
c. Remove and discard all a-rings.
d. Inspect and clean all parts in dry cleaning sol-
vent and dry thoroughly.
e . Inspect all internal parts and cylinder bore for
wear and damage. Replace worn or damaged parts.
f. Wipe new a-rings with MIL-H-5606 hydraulic
fluid prior to installation in actuator housing.
NOI.
When installing O-ring, verify that
a-ring is evenly stretched around
circumference of actuator housing
and is not twisted in retaining groove.
INST ALLATION.
a. Place actuator in pOSition on landing gear and
install attaching hardware.
Change 4
NOI.
Small end of tapered spacer must
contact actuator cylinder bearing.
b. Assure swivel fittings are free to rotate.
c . Connect hydraulic lines to actuators.
d. Operate hydraulic power pack to purge system
of air as necessary and check fluid level in reservoir.
e. Fill reservoir as needed.
f. Pressurize actuator and check for external leakage .
g. Make preload adjustment as outlined in Section VI.
h. Perform a functional test on landing gear (see
Functional Test Procedures in this section).
HYDRAULIC POWER PACK
The fully-reversible electrically-driven hydraulic
power pack unit is located in the left side of the aft
fuselage. It contains a reversible electric motor-
driven hydraulic pump, reservoir, low pressure
control valve, high pressure control valve, thermal
relief valve and a gear-up check valve. The hydrau-
lic high pressure control valve limits system pres-
sure during retraction cycle of the gear. The hydrau-
lic low pressure control valve limits system pressure
during the extend cycle of the gear. The thermal re-
lief valve is set to crack between 2025 and 2425 psi
should the thermal expansion of hydraulic fluid exceed
normal operating pressures. A gear-up check valve
opens to allow retraction pressure to the gear while
the hydraulic pump is running and closes when the
pump is off to hold pressure in the hydraulic lines
when the gear is retracted. Any problem in the proper
operation of the system can be isolated by performing
the Hydraulic Power Pack Check. If any of the hydrau-
lic power pack components are malfunctioning the com-
plete power pack unit must be removed and replaced
as the components are not field adjustable or repair-
able. Access to the power pack unit is gained by re-
moving the left side baggage compartment panel (see
Figure 3-5). Refer to Figure 3-3 for component parts
pressure settings and effectivity.
HYDRAULIC POWER PACK CHECK
a. Jack aircraft as outlined in Section II
b. Connect. external power source regulated to
14.1 (± .1) volts capable of delivering 70 amperes.
c. Add MIL-H-5606 hydraulic fluid to power pack
fluid reservoir as required.
d. Clear vent port by backing screw and washer I
out to allow a 0.06 inch minimum clearance between
power pack boss and bottom of rubber washer seal.
e. Disconnect gear actuation lines in left wheel
well at bulkhead fittings in wing rib (see Figure 3-6).
f. Install 0 to 3000 psi pressure gage at each of the
gear up and gear down hydraulic lines (see Figure 3- 6).
NOTE
Do not disconnect emergency gear down line .
Do not loosen any line while system
is pressurized.
3-9
Copyright Commander Owners Group 2013 All Rights Reserved
**unofficial copy**