Each trouble analysis procedure provides preliminary data, such as tools and equipment, manpower requirements, and material. In the block type of troubleshooting sheets, the procedure is arranged in the order of most likely occurrence. The sheet contains a NO-YES response to direct maintenance personnel through a logical series of steps. These directed responses assist in isolating the malfunction. When the requirements of a step are satisfactory, you go to the YES column and perform the referenced step. When the requirements of a step are not satisfactory, you go to the NO column and perform the referenced step. This method is continued until the malfunction is isolated and corrected. The original checkout procedure must then be repeated to ensure that the malfunction has been corrected. TROUBLESHOOTING PROCEDURES Troubleshooting procedures are similar in practically all applications, whether they be mechanical, hydraulic, pneumatic, or electrical. These procedures are certainly adaptable to all aircraft maintenance, as well as other types of installations. Auto mechanics use these steps to find and repair malfunctions in automobiles. You will use the same procedure to find and repair malfunctions within aircraft systems. Clarification of the seven distinct troubleshooting steps previously mentioned are as follows: 1. Conduct a visual inspection. This inspection should be thorough and searching-checking all lines, units, mechanical linkage, and components for evidence of leaks, looseness, security, material condition, and proper installation. During this visual inspection, the hydraulic system should be checked for proper servicing-reservoir for proper level, accumulators for specified preload, etc. 2. Conduct an operational check. The mal- functioning system or subsystem is checked for proper operation. This is normally accomplished by attaching the support equipment to the aircraft, which supplies a source of electrical power and pressurized fluid to operate the hydraulic system. In some instances, however, the aircraft may be ground checked by using aircraft power and equipment. Whatever the case, during movement of the malfunctioning unit, the AM checks for external leakage, the correct direction of component movement, its proper sequence of operation, speed, and whether the complete cycle was obtained. 3. Classify the trouble. Malfunctions usually fall into four basic categories–hydraulic, pneumatic, mechanical, and/or electrical. Using the information gained from steps 1 and 2, the AM determines under which classification the malfunction occurs. Something affecting normal flow of hydraulic fluid would be classified under the hydraulic classification. The flow of fluid may be affected by external and internal leakage, total or partial restriction, or improper lubrication. Something affecting the normal flow of compressed gases is classified as a pneumatic malfunction. This type of malfunction stems from the same general sources as hydraulic malfunctions mentioned in the previous paragraph. Most units that operate hydraulically or pneumat- ically incorporate mechanical linkage. If a discrepancy in the linkage exists, it will affect the system’s operation. Mechanical discrepancies should be found during visual inspections, and they are usually in one of the following categories: worn linkages, broken linkages, improperly adjusted linkages, or improperly installed linkages. Many hydraulic units incorporate electrical compo- nents to operate or control them. You must be able to determine if the electrical system is functioning normally—electrical malfunctions will usually be a complete power failure, circuit failure, or component failure. 4. Isolate the trouble. This step calls for sound reasoning, a full and complete knowledge of hydraulic theory, as well as a complete understanding of the affected hydraulic system. During this step, you must use your knowledge and the known facts to determine where the malfunction exists in the system. Usually the trouble can be pinned down to one or two areas. This is done by eliminating those units that could not cause the known symptoms and those that can be proved to be operating normally. 5. Locate the trouble. This step is used to eliminate unnecessary parts removal, thus saving money, valuable time, and man-hours. Often, you have determined what unit or units in the system could have caused the malfunction, thus verifying the isolation step. Both hydraulic and pneumatic malfunctions are verified in the same manner. You remove lines and inspect them for the correct flow in or at the suspected unit. Internal leaks may occur in valves, actuators, or other hydraulic units. Any unit that has a line that could carry fluid to “return” is capable of internal leakage. Mechanical malfunctions are located by closely observing the suspected unit to see if it is operating in 3-17