transducer excitation and output coils. The rotatingelectronics cylinder rectifies the rotary transformerexcitation to 24 V dc for powering the hub-mountedtransducer and receives the transducer output. Therotating electronics cylinder is attached to the prairie airtube extension at the end of the OD box. The cylinderelectronically regulates the transducer output to- 3 kHzfor the rotary transformer. For a more detaileddescription of this system’s operation, consult theDDG-51 propulsion plant manual or the DDG-51 CPPsystem technical manual.Emergency OperationP for the online strainers andIf the electronic pitch control system becomesinoperative, you must instruct your personnel to shift tomanual control at the OD box. Manual operation isaccomplished by shifting the two changeover valvelevers on the manifold block assembly from AUTO toMANUAL. The propeller will remain at the pitch setinitiated at the time of the change. You can change thepitch by operating the control valve lever and observingthe local pitch indicator.Once the problem with the electronic controls hasbeen corrected, shift back to automatic operation.Before initiating the change from MANUAL to AUTO,be sure the pitch command signal from the controllingremote station matches the actual pitch setting at thetime the mode change (manual to auto) is initiated. Shiftthe two changeover levers simultaneously to the AUTOposition. If the command signal and actual pitchsettings do not match, the pitch will automaticallychange to the commanded pitch upon completion of themode change.a .If the local manual mode is inoperative, shift thechangeover valves to the OFF position, secure thehydraulic oil power module (HOPM), and setemergency pitch according to engineering operationalb.sequence system (EOSS) procedures.NOTEWhen operating in the emergency ahead mode,the OD box temperature must be monitoredcontinuously. You may have to apply cooling waterto the OD box housing to maintain the temperaturebelow 160°F. Remember, the most effective andpreferred method to maintain OD box temperaturesis the use of prairie air.CRP/CPP SYSTEM INSPECTIONSThe following is a list of routine checks and servicesthat should be made to the CRP/CPP system whileunderway:1. Hourlya.b.c.d.Check the OD box temperature, 160ºFmaximum (150°F DDG-51 class).Check the hydraulic system oil pressures;ensure all comply with EOSS.Check the prairie air rotoseal for leaks.Check the Dfalters.2. Each watcha. Check the hydraulic oil level in the sump andhead tank.b. Inspect the hydraulic system for leaks andvibration.3. Before entering port or any restrictedmaneuvering situationa. Verify the control system response bydecreasing pitch slightly and notingresponse.b. Verify the pump (attached or electric)operation depending on ship class.4. When the system is securedCheck the oil level in the head tank. If thehead tank oil level is low, replenish oil asnecessary by operating the system until theoil level returns to normal.Inspect the oil for water contaminationperiodically.CRP/CPP TROUBLESHOOTING ANDMAINTENANCEEven though the CRP/CPP systems installed on agas turbine-powered ship use the same types of pumpsand fluids as the MRG LO system, they are much moresophisticated.Paying close attention to systemoperating pressures is your most important step insuccessfully troubleshooting any problem and makingthe appropriate repairs. The following paragraphs willdescribe some of the common problems associated withsystem pressure and the methods you can use to identifythe component or components that might be causing the3-16
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