TM 1-1520-240-106-6-16 CAUTIONDo not press the sequence valve plungerunless the ramp is down.6-6-24. Ramp Control Sequence Valve.A mechanically operated sequence valve controls thesequence of the cargo door and ramp operation (fig.6-6-9). The valve is below the ramp control valve at theramp hinge line. A plunger on the top of the valve ismanually pressed to hold the cargo door at full openduring ramp operation. The plunger can be locked in thedepressed position by rotating a retainer pin which ex-tends from the side of the valve.6-6-25. Pressure Actuated VAlve.Ramp operation is stopped during cargo door operationby a hydraulic pressure actuated valve. The valve islocked near the ramp control valve (fig. 6-6-8). A plungerprovides manual override of the valve if it sticks.6-6-26. Accumulator Gage.A gage at station 534, right side indicates APU accumu-lator pressure in psi (fig. 6-6-8). A pressure reading onthe accumulator gage in excess of 2,500 psi is sufficientfor operating the ramp.6-6-27. Equipment Loading and Unloading.The following procedures should be observed in prepar-ing the helicopter for cargo transport mission:a.Doors — Open.b.Parking brake — ON.c.Troop seats — Stow.d.Cargo compartment — Clean.e.Tiedown devises — Check, for type and quanti-ty.f.10,000 lb tiedown fittings — Install as required.g.Loading aids — Check, for condition and opera-tion.h.Weight and balance data — Check.i.Emergency equipment — Check.j.Emergency exits — Inspect.k.Cargo load — Inspect.6-6-28. Ramp Operation.6-6-29. Normal Operation.WARNINGWhen the RAMP PWR switch is OFF, besure the RAMP CONTROL VALVE remainsat STOP. If the RAMP CONTROL VALVE ismoved to UP or DN, the ramp may free fall.1. Lower the ramp as follows:a. RAMP PWR switch — ON.NOTEPerform step b. and c. only if the ramp is low-ered with accumulator pressure.b. APU accumulator gage — Check 2,500psi or more. If pressure reading is below2,500psi, operate the hand pump tobuild up pressure.c. EMERG UTIL PRESS valve — Open.Figure 6-6-9. Sequence Valve Operation
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