CHAPTER 4 HYDRAULIC CONTAMINATION AND RELATED SERVICING/TEST EQUIPMENT

CHAPTER 4 HYDRAULIC CONTAMINATION AND RELATED SERVICING/TEST EQUIPMENT Chapter Objective: Upon completion of this chapter, you should have a working knowledge of hydraulic contamination. You should be able to identify the support equipment used in servicing, troubleshooting, repairing, and maintaining aircraft hydraulic systems. All modern naval aircraft contain hydraulic systems that operate various mechanisms. The number of hydraulically operated units depends upon the model of aircraft. The average operational aircraft has about a dozen hydraulically operated units. Aircraft hydraulic systems are designed to produce and maintain a given pressure over the entire range of required fluid flow rates. The pressure used in most Navy high-performance aircraft is 3,000 psi. The primary use of hydraulic fluids in aircraft hydraulic systems is to transmit power, but hydraulic systems perform other functions. Hydraulic fluid acts as a lubricant to reduce friction and wear. Hydraulic fluid serves as a coolant to maintain operating temp- eratures within limits of critical sealant materials, and it serves as a corrosion and rust inhibitor. Critical functions of hydraulic systems maybe impaired if the hydraulic system fluid is allowed to become contaminated beyond acceptable limits. Hydraulic fluid contamination is defined as any foreign material or substance whose presence in the fluid is capable of adversely affecting the system performance or reliability. Contamination is always present to some degree, even in new, unused fluid. Contamination must be below the level that adversely affects system operation. Hydraulic contamination control consists of requirements, techniques, and practices that minimize and control fluid contami- nation. Remember the proverb, "An ounce of prevention is worth a pound of cure." HYDRAULIC CONTAMINATION CONTROL PROGRAM Learning Objective: Recognize the Navy's hydraulic contamination control program. Hydraulic contamination in Navy and Marine Corps aircraft and related support equipment (SE) is a major cause of hydraulic system and component failure. Every technician who performs hydraulic maintenance should be aware of the causes and effects of hydraulic contamination. You should follow correct practices and procedures to prevent contamination. Supervisory and quality assurance personnel must know and ensure compliance with accepted standards. Each maintenance level needs to accept their applicable responsibility. Supervisory personnel at each level of maintenance should indoctrinate and train personnel and implement procedures that apply to that level of maintenance. The Hydraulic Contamination Control Program is defined in the Naval Aviation Maintenance Program (NAMP), OPNAVINST 4790.2 (series). Within the scope of this program, training must be consistent with the objectives of an effective aircraft hydraulic system contamination control program. At all mainte- nance levels, personnel must be trained in matters pertaining to hydraulic systems contamination control using Hydraulic Contamination Control Training Device 4B38A or Videotape Number 802577DN. The Hydraulic Contamination Control Program requires you to follow the correct procedures during fluid sampling, maintenance procedures, and practices. FLUID SAMPLING Contamination measurement standards and acceptability limits define and control hydraulic contamination levels. The maximum acceptable hydraulic fluid particulate level is Navy Standard Class 5 for naval aircraft, and Navy Standard Class 3 for related SE. The contamination level of a particular system is determined by analysis of a fluid sample drawn from the system. Analysis is 4-1