As a Gunner's Mate, maintenance is at the heart of your profession. For you, the art of gunnery comes down to your ability to get the "rounds out" on command safely. The reliability of your gun is directly related to your skill as a maintenance person. This chapter will cover a wide variety of maintenance items. We will begin by discussing the essentials of preventive and corrective maintenance. Following this, we will discuss lubrication, corrosion control, barrel maintenance, and tools. We will then discuss the content and use of equipment maintenance manuals. We will also provide some practical instructions for performing common maintenance procedures, such as replacing hydraulic seals and making mechanical adjustments. Finally, we will discuss some safety precautions that apply to maintenance.

The information in this chapter assumes you have a functional knowledge of the Maintenance and Material Management (3-M) Systems. You may find it useful to review the requirements of the 3-M Systems before beginning this chapter.

PREVENTIVE AND CORRECTIVE MAINTENANCE

LEARNING OBJECTIVES: Discuss the difference between the maintenance completed by the ship's force, tender repairs, and repairs handled by the shipyards. Briefly describe the Phased Maintenance Program (PMP) and its primary elements.

The term maintenance includes many different types of tasks. However, all maintenance is classified as either preventive or corrective. In this section we will discuss the elements and implications of preventive and corrective maintenance. The intent of this section is to provide you with a sense of the importance of your role in keeping your gun operating smoothly and safely.

PREVENTIVE MAINTENANCE

Of the two main classes of maintenance work, the most important, which accounts for most of the maintenance work you do, is preventive maintenance. Preventive maintenance consists mainly of the regular lubrication, inspection, and cleaning of your equipment. The purpose of preventive maintenance is to prevent malfunctions before they appear and discover existing malfunctions before they become critical. Preventive maintenance is based on the well-known principle that an ounce of prevention-in the form of adequate routine maintenance-is worth a pound of cure-in the form of emergency repair, replacement, and overhaul.

Preventive maintenance is neither dramatic nor exciting. While the need for routine lubrication is obvious, you may envision your leading petty officer (LPO) as being a little obsessive when it comes to gun mount cleanliness and inspection. You may think time spent cleaning and inspecting components that have always been in good shape to be a waste. However, you will realize this time has been well spent when you consider the impact that an undiscovered hydraulic leak or a missing retainer clip could have in the midst of firing the gun. These situations represent major casualties just waiting to happen with serious and sometimes fatal consequences. By taking a little time and trouble to do routine preventive maintenance now, you can save yourself a lot of work later by heading off breakdowns and time-consuming emergency repair jobs.

The Navy uses maintenance requirement cards (MRCs) in the planned maintenance system (PMS) to make sure routine maintenance jobs are done at the required regular intervals-daily, weekly, monthly, and so on,-and no steps are forgotten.

MRCs are obtained from the Gunner's Mate under whom you work. They provide a step-by-step guide for performing a specific maintenance action. MRCs prescribe the minimum required preventive maintenance for a given gun mount. MRCs cover all lubrication, some inspections, and some cleaning. Anyone with a little training can perform maintenance from an MRC. However, an MRC will not tell you to inspect mechanical linkages for cracks or missing retainer clips while you lubricate each of its pivot points. It will not instruct you to determine the cause of a fresh puddle of hydraulic fluid on the deck under a piece of gun loading machinery and initiate steps to have it repaired. As you become more knowledgeable in gun mount maintenance, you will develop an appreciation for the importance of these unstated commonsense preventive maintenance practices.

As stated earlier, MRCs cover all minimum lubrication requirements. However, you or your LPO may determine that it is necessary to lubricate certain mechanisms more frequently during very heavy operational conditions. This is acceptable and shows that you possess a good understanding of the actual purpose of maintenance-to keep the system operational!

Inspections required by MRCs normally consist of checks that verify fluid levels in hydraulic and gearbox reservoirs and mechanical adjustments and clearances. The term inspection may also be applied to MRC-directed equipment operational checks, electrical continuity checks, and gun order checks.

A good example of cleaning maintenance required by an MRC is the removal of lubricants from the gun barrel before firing and the removal of residue from the barrel after firing. Other cleaning maintenance covered by MRCs includes the cleaning of electrical contacts and the removal of excess grease from around grease fittings after they have been lubricated. The general cleanliness of your equipment is also an important factor. Dirt and dried hydraulic fluid on machinery make it less likely that you will notice a fresh leak or damaged component. It is also much more pleasant to work on clean equipment.

In addition to MRC-guided preventive maintenance, you have the system maintenance manuals. These manuals contain detailed descriptions of the operation and care of the gun systems. You should be intimately familiar with these manuals. They include all the clearances and tolerances for the mechanical systems of the guns as well as detailed procedures for component replacement. MRCs do not require the verification of the majority of these adjustments and clearances. Over the years, mechanical equipment wears, the hull of the ship twists, and mechanical adjustments slip. For this reason it is a good practice to review system maintenance manuals to identify these adjustments and clearances. Routinely including the verification of some of these adjustments in your preventive maintenance schedule will serve to extend your knowledge of the operation of the system while helping to ensure its reliability. These adjustments also make good topics for professional training. Mechanical adjustments are covered in more detail later in this chapter. Further discussion on maintenance manuals is also covered later in this chapter.

NOTE: Be sure to consult with your supervisor before attempting to correct any equipment misalignments.

Let's tie all these ideas together as we close out this section on preventive maintenance. As a maintenance person you have three good tools available to help you keep your equipment operating at peak performance-MRCs, system maintenance manuals, and common sense. MRCs form the foundation of preventive maintenance by providing minimum maintenance standards. System maintenance manuals provide additional in-depth system operation and maintenance information. Effective preventive maintenance requires a high level of technical knowledge mixed with some good old-fashioned common sense. You can do the minimum required maintenance and be within the letter of the law, but still have the least reliable gun on the waterfront, and be known as a poor maintenance person. You may believe that you are a maintenance person because you can complete the MRCs assigned to you. However, if the extent of your maintenance expertise encompasses only the requirements of your systems MRCs, then you are really only a maintenance person's helper. A maintenance person has, or is continually working on, an in-depth understanding of the system. When you invest that little extra time on the gun while performing routine lubrication, you can take a good look at the gun to make sure all is in order. You will see in the next section how preventive maintenance is the foundation of corrective maintenance.