TM 1-1520-240-102-6-3/(2-6-4 blank)bus through the RAMP PWR switch and the RAMPEMER CONT circuit breaker on the No. 1 PDP.2-6-9. Hydraulic System Service Module.A service module, on there right side of the cargocompartment above the ramp, provides for filling the twoflight control hydraulic system and the utility hydraulicsystem. It consists of a filler assembly, a two-stage handpump, and a selector valve for selection of any of thethree hydraulic systems for filling.2-6-10. Utility System Hand Pump.A two-stage hand pump, on the right side of the cargocompartment above the ramp, is used to pressurize theAPU start accumulators for APU starting. Also, in con-junction with the EMERG UTIL PRESS controllablecheck valve, it may be used to operate the ramp anddoor.2-6-11. EMERG UTIL PRESS Controllable CheckValve.The EMERG UTIL PRESS controllable check valve islocated above the hand pump. It allows APU start accu-mulator pressure to be used for operation of the ramp orany other subsystem (brakes, swivel locks, etc.). Whenthe APU motor pump or utility pump is not operating, it isnot necessary to use the hand pump unless the accumu-lator is discharged. When the accumulator is discharged,the EMERG UTIL PRESS controllable check valve inconjunction with the hand pump may be used to operatethe ramp and hatch. The NORMAL position of the checkvalve is used when the system is pressurized by the APUor by the utility hydraulic pump. When the engines andthe APU are not operating, the controllable check valveis set to OPEN, the ramp control handle is set to UP orDN, and the hand pump is operated. When ramp move-ment is completed, the ramp control handle is set toSTOP and the controllable check valve is set to NOR-MAL. This valve may also be used in flight, in the eventof utility pump or system failure to provide accumulatorpressure to the subsystems. 2-6-12. Hydraulic Pressure Cautions.Three hydraulic pressure caution capsules, one for eachflight 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 labeled712 NO. 1 HYD FLT CONTR, NO. 2 HYD FLT CONTR,and UTIL HYD SYS, 714A HYD 1, HYD 2, and UTILHYD SYS. Each capsule is electrically connected to apressure switch in the corresponding control module.Whenever hydraulic pressure drops below 1,800 psi inone of the flight control systems or the utility system, thatsystem caution illuminates. The caution capsule extin-guishes as increasing pressure approaches 2,300 psi.Caution capsules operation is independent of hydraulicpressure indicator operation. Power for these capsulesis 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.
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