Eliminating fungus in aircraft fuel tanks

The intrinsic water content of fuel and atmospheric moisture condensation on fuel tank walls help microbes flourish. Current treatment involving periodic removal of water, cleansing of the tanks and addition of chemicals to the fuel is not effective enough. Scientists launched the EU-funded project 'Development of new antimicrobial nanostructured durable coatings for fuel tanks' (AMICOAT) to solve the problem.

Project work was divided into three phases. The first phase consisted of increasing understanding of microbial growth in fuel tanks. The second phase focused on applying this newfound knowledge to the development of nano-structured antifungal coatings compatible with the fuels and their combustion. Finally, the team applied and characterised coating performance. Careful consideration was given to issues of safety and toxicity.

One of the most common culprits is Hormoconis resinae, also known as the kerosene fungus. Scientists developed two different coating formulations: a polymeric polyurethane nanocomposite and a silica sol-gel. The team dispersed the biocide agent zinc pyrithione into them. They were designed to both prevent adhesion of the microbes to the tank wall (biofilm adhesion) and to enable release of the biocides (growth inhibitors).

Tests of microbial growth inhibition demonstrated that both formulations inhibited spore germination and vegetative growth of H. resinae. In addition, they both were able to inhibit adhesion of the spores to fuel tank wall surfaces to a certain degree.

The antimicrobial nano-structured coatings developed by AMICOAT are a promising alternative to conventional treatments. Their application could significantly reduce the maintenance costs associated with water removal and fuel tank cleaning while improving aircraft performance and safety. Further, the solutions can be implemented quickly and easily for added value improvements that will enhance the competitive position of the EU aircraft industry.