In order to become proficient at the art of troubleshooting, one must be familiar with the complete system. To do this, one can become familiar with the schematics of various portions of the system, the nomenclature of the units, and their particular function within the system by studying aircraft and engine maintenance manuals.
Location of Leaks and Defects
The location of leaks and defects within the internal portions of the fuel system is usually a matter of observation of the pressure gauge and operation of the selector valves to determine where the trouble lies. Troubleshooting of the internal fuel system can be aided by visualizing the path of flow of the fuel from the fuel tank to the fuel metering device, noting the location of the pump(s), selector valves, emergency shutoff valves, etc.
The location of leaks or defects in the external portions of the fuel system involves very little time in comparison to locating leaks within the internal system. Usually, fuel leaks are evidenced by stains or wet spots, if they are newly developed, and by the presence of fuel odor. The plumbing, clamps, gaskets, supports, etc., are to be examined carefully at each inspection period. Any defect or leak in the internal or external fuel system is a potential hazard.
Replacement of Gaskets, Seals, and Packings
In order to prevent leakage of fuel, it is of utmost importance that all gaskets, seals, and packings be properly installed. Listed below are some of the general precautions that should always be observed.
When replacing units of the fuel system, it is necessary to check each part for cleanliness, ensure that all of the old gasket material is removed, and ensure that none of the old seal remains in the groove seat. Always replace old gaskets and seals with new ones, check the new gaskets and seals for cleanliness and integrity, and ensure that it is the right part for the job. Mating surfaces should be perfectly flat so that the gasket can do the job for which it is designed. Screws, nuts, and bolts that hold units together should be evenly tightened or torqued to prevent leakage past the gasket or seal.