How Aircraft Fuel Systems are Inspected and Maintained?
The fuel system is paramount to the operation of an aircraft, allowing it to efficiently mix and combust fuel-and-air mixtures for propulsion generation. With the constant ignition of fuel and the resulting extreme temperatures and pressures that the system faces, regular inspection and maintenance should be conducted to maintain integrity and optimal operations. From standard visual examinations to testing systems, there are various procedures that are carried out to ensure the continued health of the aircraft fuel system.
During a standard inspection and maintenance procedure, mechanics will often start with a complete system inspection. At this time, the fuel system will be checked for any wear, leaks, or damage that may affect performance or jeopardize other assemblies. By removing the drain plug or fuel valves, inspectors can see if there is any sediment or contaminates to be removed. Furthermore, filter screens and vents are often cleaned thoroughly to avoid corrosion and blockages. If the fuel system has a booster pump implemented, tests are conducted to check for any leaking substances and ammeter readings are used. During the testing of the booster pump, inspectors will always be weary of any damages to the motor brushes as well.
When focusing on the inspection of the fuel tank assemblies, external surfaces should be looked over for any signs of corrosion as damages could lead to a loss of pressure or leaking fuel, both of which are extreme hazards during operations. Fittings and connections are some of the primary areas to inspect, as failures are prone to cause leaking. For specific aircraft fuel tank models that are constructed from light alloys, inhibitor cartridges may be present in order to combat corrosion in the system. If such parts are present within the assembly, they should be replaced as needed as dictated by manufacturer specifications and part condition.
For the linings and fittings of the fuel system assembly, all fasteners should be checked for their tightness and all lines for their support. To ensure proper torque is applied to all fasteners, the correct hand tools should be used that accommodate the components in question. If clamps or hose clamps cannot be tightened enough to provide a sufficient seal, they may need to be replaced. The hose itself is also an important component to look over, as materials should not be hard or inflexible. If the hose has been subject to cold temperatures and cold flows, cracking may also occur. As cracking, failing seals, and blisters may all result in leaking, replacements should be made as necessary.
Depending on the type of fuel quantity gauge that is present in the system, various components are looked over for their integrity. With sight gauges, connections are checked to ensure that there are no leaks, and the glass should be clear. With electrical gauges, connections are checked to ensure that they are secure alongside the indicator and tank units. For the fuel pressure gauge, the pointer can be looked over to see if there is zero tolerance or excessive oscillation. If there are any issues that cause the component to be defective, it should be replaced as soon as possible.
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