TM 1-1520-240-10
2-6-3/(2-6-4 blank)
bus through the RAMP PWR switch and the RAMP
EMER CONT circuit breaker on the No. 1 PDP.
2-6-9. Hydraulic System Service Module.
A service module, on there right side of the cargo
compartment above the ramp, provides for filling the two
flight control hydraulic system and the utility hydraulic
system. It consists of a filler assembly, a two-stage hand
pump, and a selector valve for selection of any of the
three hydraulic systems for filling.
2-6-10. Utility System Hand Pump.
A two-stage hand pump, on the right side of the cargo
compartment above the ramp, is used to pressurize the
APU start accumulators for APU starting. Also, in con-
junction with the EMERG UTIL PRESS controllable
check valve, it may be used to operate the ramp and
door.
2-6-11. EMERG UTIL PRESS Controllable Check
Valve.
The EMERG UTIL PRESS controllable check valve is
located above the hand pump. It allows APU start accu-
mulator pressure to be used for operation of the ramp or
any other subsystem (brakes, swivel locks, etc.). When
the APU motor pump or utility pump is not operating, it is
not necessary to use the hand pump unless the accumu-
lator is discharged. When the accumulator is discharged,
the EMERG UTIL PRESS controllable check valve in
conjunction with the hand pump may be used to operate
the ramp and hatch. The NORMAL position of the check
valve is used when the system is pressurized by the APU
or by the utility hydraulic pump. When the engines and
the APU are not operating, the controllable check valve
is set to OPEN, the ramp control handle is set to UP or
DN, and the hand pump is operated. When ramp move-
ment is completed, the ramp control handle is set to
STOP and the controllable check valve is set to NOR-
MAL. This valve may also be used in flight, in the event
of utility pump or system failure to provide accumulator
pressure to the subsystems.
2-6-12. Hydraulic Pressure Cautions.
Three hydraulic pressure caution capsules, one for each
flight control system and one for the utility hydraulic pres-
sure system, are on the master caution/advisory panel
( 712 ,fig. 2-14-5, 714A , fig. 2-14-6). They are labeled
712 NO. 1 HYD FLT CONTR, NO. 2 HYD FLT CONTR,
and UTIL HYD SYS, 714A HYD 1, HYD 2, and UTIL
HYD SYS. Each capsule is electrically connected to a
pressure switch in the corresponding control module.
Whenever hydraulic pressure drops below 1,800 psi in
one of the flight control systems or the utility system, that
system caution illuminates. The caution capsule extin-
guishes as increasing pressure approaches 2,300 psi.
Caution capsules operation is independent of hydraulic
pressure indicator operation. Power for these capsules
is supplied by the DC essential bus through the CAU-
TION PNL circuit breaker on NO. 1 PDP.
2-6-13. Hydraulic Pressure Indicators.
Three HYDRAULICS PRESSURE indicators (fig. 2-9-2),
one for each hydraulic system, are on the MAINTE-
NANCE PANEL. Refer to Section IX Utility Systems.
