matter does not enter the strut during assembly. Contamination of parts can cause a definite failure. Guarding against contamination cannot be over- emphasized. Observe the torque values specified in the 03 manual or MIM. Where a specific torque value is not specified for a threaded part, tighten the part according to the standard torque values provided in the Structural Hardware Manual, NAVAIR 01–1A—8. Some structural repair manuals and maintenance instructions manuals also contain this information. On some parts, such as the strut gland nut, tightening should conform to acceptable shop practices and common sense, unless otherwise specified. Lightly coat all preformed packings with hydraulic fluid. After all seals and parts are properly installed, the piston head is tightened and the retaining pins installed and staked into place. The piston assembly is inserted into the outer cylinder, and the gland nut is tightened to a snug fit, backed off two key slots, and locked in place. If the gland nut is too tight, it will result in binding of the thrust bearing. Two lock plates, positioned 180 degrees apart on the collar and gland nut, are secured with screws and lockwired to hold the gland nut in place. Use the double twist method of applying the lockwire so that tension of the wire tends to tighten the nut. Bench Testing With the strut fully compressed and in the vertical position, service the strut with hydraulic fluid. Install the air valve on the strut and torque to 100-110 inch-pounds. Place the strut fully extended in a horizontal or vertical position and inflate with dry nitrogen to the normally extended pressure specified in the MIM or 03 manual. Ensure that the strut shows no leakage after a 1-hour interval. If the strut fails the bench test, it is tagged to show the portion of the test that failed. Then it is deflated, flushed with preservative hydraulic fluid, and forwarded to the next higher level of maintenance. If the strut passes the bench test and is not to be installed on an aircraft immediately, flush with preservative hydraulic fluid before sending it to supply. If any parts other than those listed as replaceable at the intermediate level of maintenance are faulty, tag the strut and forward it to the next higher level of maintenance. The VIDS/MAF is closed out to account for man-hours expended in attempting repairs before the strut is declared beyond the capability of maintenance (BCM). If a Quality Deficiency Report (QDR) form was attached to the strut by the removing organizational maintenance activity, complete the QDR and submit it according to the instructions provided in OPNAV Instruction 4790.2 (series). Any unusual failure or strut malfunction should be reported by the submission of a QDR so that failure trend patterns or isolated instances maybe reviewed for possible higher echelon action. Forward the No. 4 copy of the MAF and the hard copy of the QDR with the strut to the next higher level of maintenance. BRAKE SYSTEMS Learning Objective: Identify the three major brake systems and recognize the operation of the emergency brake systems. Three types of brake systems are currently in use on naval aircraft. They are the independent-type brake system, the power boost brake system, and the power brake control valve system. In addition, there are several different types of brake assemblies currently in use. INDEPENDENT-TYPE BRAKE SYSTEM In general, the independent-type brake system is used on small aircraft. This type of brake system is termed independent because it has its own reservoir and is entirely independent of the aircraft’s main hydraulic system. The independent-type brake system is powered by master cylinders similar to those used in the con- ventional automobile brake system. However, there is one major difference–the aircraft brake system has two master cylinders while the automobile system has only one. An installation diagram of a typical independent- type broke system is shown in figure 12-22. The system is composed of a reservoir, two master cylinders, and mechanical linkage, which connects each master cylinder with its corresponding brake pedal, connecting fluid lines, and a brake assembly in each main landing gear wheel. Each master cylinder is actuated by toe pressure on its related pedal The master cylinder builds up pressure by the movement of a piston inside a sealed fluid-filled cylinder. The resulting hydraulic pressure is transmitted 12-28