Aircraft Fuel Cells Repair

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Overview

In the previous post, we shared with you the causes of corrosion in aircraft fuel tanks & how to control and remove corrosion. If your aircraft fleet is affected by corrosion that has resulted in aircraft fuel leaks, it is time for you consider the repair in order to prevent hazardous situation during flight. Repairing fuel leaks can be time consuming, especially finding the source of the leak. The steps described later in this post will help you in finding the source of the leak and seeking professional help if needed in fixing the leak. It is important to put a process in place for scheduled maintenance of aircraft fuel tanks in order to prevent costly repairs.

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.

For more information on Scheduled Maintenance of Aircraft Fuel Tank & Fuel Leak Repairs visit our Website.

 

 

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Overview

In the previous post, we shared with you the importance of scheduled inspection and maintenance to maintain flightworthiness. We also shared few tips on understanding the structure of aircraft fuel cells. Once your aircraft has gone through inspection, and has been identified for repairs, you can make use of these tips to perform the next step, repairs. It is critical for you to be aware of FAA approved methods for Repairs and to comply with manufacturer’s guidelines.

Aircraft Fuel Cells Repair

After a thorough inspection, aircraft fuel cells repairs can be initiated. The Federal Aviation Association (FAA) has approved some methods for aircraft fuel cells repair. These are:

  • Heat Cured Factory Repairs
  • Air Cured Field Repairs
  • Coatings – only some are approved.

Repairs must be made in accordance with the manufacturer’s instructions, and ideally by a seasoned repair technician. Repairs can be made in a variety of methods, but in particular, after a welding repair there are important steps that must be taken.

Removal of Flux after Welding

If flux is not completely removed, corrosion can occur. Following these steps will ensure that all flux is removed after the aircraft fuel cell repair is complete:

  1. Wash the inside and outside of the tank with plenty of hot water. Drain thoroughly.
  2. Immerse the tank in either 5 percent nitric or 5 percent sulfuric acid solution. NOTE: If the tank cannot be immersed, then fill it with either solution and wash the outside with the same.
  3. Leave the acid solution to remain in contact with the weld for approximately one hour. Rinse thoroughly with clean water.
  4. Apply acidified 5 percent silver nitrate solution to a small amount of the rinse water used in the prior step. If a heavy white precipitate forms, the cleaning must be repeated.

Regardless of the type of repair performed, a complete aircraft fuel cells inspection is the first step to ensuring thoroughness and completeness of repairs and maintenance procedures. Each repair should be executed using steps outlined by the manufacturer. To keep the aircraft flight ready and in good shape, perform regular inspections and maintenance. Aircraft fuel cells are no exception and a critical component of safety procedures.

For more information on Aircraft Fuel Cells Inspection & Repairs visit our Website.

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Overview

Aircraft fuel cells require continual maintenance and often repair to maintain flightworthiness. Aircraft fuel is typically stored in three ways:

  • Metal tanks
  • Wet wing or integral tanks
  • Bladders or Fuel Cells

Aircraft fuel cells are very common and should be inspected regularly to keep them in good working condition. To understand more about appropriate maintenance and repair, it is prudent to first understand how fuel cells are made.

Aircraft fuel cells are manufactured by combining two or more layers of material that bonds two liners – inner and outer. It is important that the inner layers are non-porous and resistant to fuel vapors. Outer layers protect the cell from the elements, including heat, ozone and humidity. If manufactured and maintained correctly, aircraft fuel cells can last as long as 20 years.

Start With an Aircraft Fuel Cells Inspection

Performing a thorough inspection is always the first step of any good maintenance process. By inspecting the aircraft fuel cells for general condition, security of attachment and evidence of leaks, the technician knows where to begin. In addition, a thorough examination of fuel tanks or fuel cell vent lines, fuel lines and sump drain attachment fittings is required.

After the baseline review, a more detailed inspection is required in order to determine the correct aircraft fuel cells repair or maintenance.

First, de-fueled tanks should be purged of any explosive fuel/air mixtures. Use the manufacturer’s service instructions to ensure appropriate procedures.  Once complete, the following can be used as a guide to complete the aircraft fuel cells inspection:

  1. Integral Tanks – inspect the interior and seams for any sealant deterioration or corrosion, paying particular attention to the sump area. Check for leaks around skin joints, rivets, screws and bolts. Leaks are categorized as follows:
    1. Slow Seep – very slow fuel seepage in a small area that does not reappear in a short time frame.
    2. Seep – leak that appears in less than an hour after it was wiped dry.
    3. Heavy Seep – fuel leak that reappears immediately after it was wiped dry.
    4. Internal Metal Tanks – check the exterior and interior for corrosion and chafing. Also look for any dents or other anomalies. Sump areas are often an issue, so pay particular attention to these areas, particularly in cases where the sumps are made of cast material.
    5. Flexible Aircraft Fuel Cells – often referred to as bladders, these fuel cells should be inspected for cracking and other signs of deterioration. Bladders should not be allowed to dry out. Additionally, an inspection of the fuel tank caps for appropriate size and type should be performed, as well as determining if the “O” rings are in good condition.

For more information on Aircraft Fuel Cells Inspection visit our Website.

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