The Chemical Resistance of Epoxy Adhesive Joints Exposed to Aviation Fuel and its Additives

Adhesively bonded structure and bonded composite repairs are often exposed to aviation fuel during service. A relatively limited number of studies examining the influence of fuel and the many additives it contains have been made. The current report details experimental studies that have examined the influence of fuel and common additives such as lubricity and deicing agents on the fracture toughness of metal and composite bonded adhesive joints. The studies aimed to determine if a series of reference fuels containing each of the additives may affect adhesive bond durability. Current results suggest that the bond durability of adhesive joints exposed for several thousands hours to fuel environments may reduce. Concentrated mixtures of water and deicing agent, which were prepared in order to simulate the environment in the bottom of fuel tanks, may also reduce joint fracture toughness. The present studies highlight the complexity of examining the influence of fuel environments on adhesive joints and the need for further research to more quantifiably assess possible mechanisms of bond degradation in typical aircraft operating environments.