MAJOR LEAK.- A major leak can provide the same symptoms as a loss of hydraulic oil pressure, depending on the location of the leak.

We have just told you about some of the components you should check when you detect a loss of pitch control or a loss of hydraulic oil pressure. Now, we will discuss some of the most common maintenance procedures you as a supervisor will expect your personnel to perform.

Cleaning and Lubrication Cleaning is a continuous task. As a GS supervisor, you are already aware that good housekeeping practices must be maintained and passed on to your subordinates. The responsibilities for cleaning and lubricating the components of the CRP/ CPP systems are very similar to those for the MRG LO system. This is because the majority of the components that require cleaning in both the MRG LO system and the CRP/ CPP systems are valves. When cleaning the valves of the CRP/ CPP systems, be sure to pay close attention to detail. Attention to detail is important because most of the valves and piping of the CRP/ CPP systems are located in the bilge area. Valves in the bilge area are constantly exposed to corrosive elements.

Other components that require cleaning and lubrication are the two CRP/ CPP pump couplings. These pump couplings are not cleaned and lubricated as frequently as the valves, but their cleaning and lubricating are still very important responsibilities.

Alignments and Adjustments You will routinely supervise alignments and adjustments to couplings and other system components. Your personnel usually perform these tasks after general maintenance (cleaning and lubrication). Alignments and adjustments are either scheduled or conditional. During the cleaning process, for example, you may discover that a coupling requires an alignment check or adjustment.

The CRP/ CPP system is one of the few systems that you as a supervisor will be required to train your personnel to closely monitor locally. Local monitoring is necessary because of the lack of remote monitoring capabilities. You will also be required to train your personnel to make the necessary mechanical and electrical adjustments. Your personnel will periodically perform these procedures through your ship's PMS. Remember, first you must monitor the operation of the CRP/ CPP system as a whole, and then isolate individual components (one at a time) to ensure they are functioning properly. The following paragraphs contain some of the components you maybe required to adjust and the functions they are designed to perform.

UNLOADING VALVE.- The unloading valve unloads the pressure of the attached pump back to the sump if the electric pump is operating and functioning properly.

SEQUENCING VALVE.- The sequencing valve serves two purposes:

(1)   It maintains a back pressure on the system to ensure that a minimum of 400 psi is supplied to the inlet side of the reducing valve, and

(2) it provides high-pressure oil to the OD box.

REDUCING VALVE.- The reducing valve provides control oil to the OD box.

AUXILIARY SERVO RELIEF VALVE.- The auxiliary servo relief valve relieves excess control oil pressure back to the sump.

MAIN RELIEF VALVE.- The main relief valve relieves excessive pump pressure, either from the electric pump or attached pump, back to the sump.

Besides adjusting the components at the OD box, both mechanical and electronic pitch position alignment checks must be accomplished periodically. These checks will not only require your expertise to train your personnel, but also require your presence while they are being accomplished.

MECHANICAL ALIGNMENT.- The mechani-cal alignment procedure is basically the same for all the ship classes. This procedure is performed according to the PMS and is used to detect valve rod separation (unscrewing) or elongation. Remember, two people will be required to perform this check One must be positioned at the OD box and the other at the HOPM, and they must be able to communicate with each other (sound-powered phones or walkie-talkies). This test is normally fairly easy to accomplish if no problems are encountered. By problems we mean the pitch scale and the pitch position pointer being off by more than 1/ 16 of an inch. If this difference cannot be explained by thermal growth or contraction of the valve rod assembly, it will be necessary to verify that all connections in the valve rod assembly are tight. If the position of the pointer and pitch scale is subject to question at anytime, you must verify actual position of blade 1A to the hub body marks. If the ship is not in dry dock, you must use a diver to observe and confirm hub body marks. You must have confirmation of the hub body marks at design ahead and full ahead when pitch is ordered at normal operating temperatures.

NOTE In most cases, an equipment malfunction is not the cause of the pointer and scale discrepancy. Usually, it is an operator error. To avoid this problem, make sure your personnel strictly follow the MRC and always take all measurements at the same system oil temperature.

On the other hand, if the pitch pointer and the scale difference is less than a 1/ 16 of an inch or the greater than reading is related to thermal growth or contraction, then the scale can be moved to match the pointer's position. The only drawback to adjusting the scale to match the pointer is that an electronic alignment (calibration) must be performed

ELECTRONIC ALIGNMENT.- The electronic alignment procedures differ depending on the ship class. But, one thing will always be the same. To accomplish any of these procedures, the ship must be in dry dock or you will require the assistance of a diver. All adjustments made to align the mechanical (actual) pitch and electronic display indications must be verified with the actual blade position on the propeller hub. There is one electronic alignment procedure (electronic pitch indicating [EPI] system calibration) on the DDG-51 class that can only be accomplished when the ship is in dry dock.

REMOVAL AND REPLACEMENT OF COMPONENTS The CRP/ CPP system seldom requires the removal or replacement of components. However, there is one

component that you will be required to replace- the electrohydraulic servo valve. As previously discussed, this valve is in constant use and its probability of failure is much higher than any other component in the system.

There is only one other set of components that you will need to remove frequently- the system's filters. In fact, you will need to remove these filters even more frequently than the electrohydraulic servo valve. This is because you will need to remove the filters for periodic cleaning according to the PMS. Of course, you will also need to remove them in the event of a casualty.

SUMMARY In this chapter, we have discussed many of the factors that affect GTE performance, power train operation and maintenance, and propulsion systems. As you prepare for advancement, you must continue to learn and increase both your leadership skills and technical expertise. You must be prepared to train and supervise your subordinates. Read the various reference materials cited in this chapter to increase your understanding of the information that was presented.