Proper maintenance is critical to preventing aircraft fuel leaks, particularly when inspecting for corrosion. Repairs are often costly and lengthy, grounding planes for much longer than if an appropriate maintenance routine was followed. To ensure that an aircraft stays airworthy, it is important to first understand what causes corrosion and the most effective means of controlling it.
Fuel contamination causes corrosion in aircraft fuel tanks. Bacteria is the primary cause of fuel contamination and typically comes from already contaminated fuel, or failing to keep fuel tanks properly sumped and inspected. Fuel contamination occurs when standing water in the sump bottoms, or contaminated fuel, hosts organisms that live in petroleum products. These organisms, called cladosporium resinae and pseudomonas aeroginosa, live in the water and feed off hydrocarbons in the fuel. The waste products of these organisms create water, sludge and acids that eventually cause corrosion.
Corrosion control in aircraft fuel tanks starts with proper maintenance. There are no products that can completely prevent this bacteria growth; therefore, ensuring a proper maintenance routine is executed is the only way to keep corrosion in check. Fortunately, there are several products that will minimize the bacteria, and using these in parallel with a good maintenance routine will help prevent costly repairs.
If corrosion is found in the fuel system, the first step is to thoroughly inspect the entire fuel system. Damage assessment is necessary to determine the extent and necessary next steps, such as aircraft fuel leaks repair. To prepare, first document the corrosion damage. Reworking corroded areas requires multiple steps, so it is important to first document all areas corrosion appears.
Rework involves cleaning and stripping of all finish from the corroded areas, removal of corrosion products, and restoration of the surface protective film. Following rework, repair of corrosion damage will include removal of all corrosion and corrosion products. If the damage is severe and exceeds the damage limits set by the manufacturer, the part must be replaced.
Removing corrosion is a detailed and lengthy process involving blast cleaning and blending of reworked areas with surrounding surfaces. Continued cleaning with polishers and brighteners will provide corrosion control in aircraft fuel tanks going forward.
Aircraft Fuel Leaks Repair
Corrosion can cause your fuel tank to be compromised, causing leaks and other significant problems. A fuel leak can ground an aircraft for days or even weeks, as time consuming repairs are performed. In fact, aircraft fuel leaks repair is one of the most time consuming repairs. The steps occur over days, rather than hours, and require intense scrutiny to ensure appropriate leak repair.
The first step is to perform a thorough inspection. During this step, it is crucial for several questions to be answered, including:
- When does the leak appear?
- Is it leaking only when the tank is full?
- Does the leak stop when the tank is only half full?
- Does it leak continuously?
- Where is the leak visible on the aircraft?
- Is the leak only coming from a rivet?
Next, confirm the type of fuel system in your aircraft. The manufacturer's maintenance manual provides important information about your fuel tank system. There are three primary fuel tank types - integral or "wet wing", fuel cell, and built-up metal or fiberglass inside the wing. Each requires specific steps to perform appropriate repairs.
Once you have determined the fuel tank system in your aircraft, it is time to perform a second inspection. This should be a more thorough inspection accessing the fuel tank. During this inspection, note if panels are wet or contain a strong odor of fuel. It is important to remember that leaks can travel a long way, making aircraft fuel leaks repair a difficult process.
Once leaks are discovered, the repairs can be done in the field or performed by an FAA-approved repair station. Each fuel tank requires slightly difference processes to complete the repair. Once completed, it is critical to reinstall any fuel tanks removed by using the maintenance manual procedures.
Check again for large leaks. If none are found, it is important to wait at least one more day before installing access panels to ensure that small leaks are not present. If there are no leaks, the access panels can be installed and the aircraft readied for flight.
Corrosion control in aircraft fuel tanks will prevent costly repairs and keep the aircraft flightworthy. Utilizing a continued maintenance and inspection program will keep corrosion in check and prevent the need for corrosion rework and removal, as well as aircraft fuel leaks repairs due to corrosion.