Integral Aircraft Fuel Tank Leak Classification

A parametric study has been conducted to investigate external leakage from aircraft integral fuel tanks. The effects of the following parameters on the rate of surface dispersion of fuels were examined fuel type, leakage rate, surface material, fuel and surface temperature, air flow rate over the test surface, and surface angle of inclination. The dispersing fuel films were found to be very thin 0.05 mm0.002 in. i.e., limited liquid volume flow results in extensive surface coverage. Fuels of low volatility such as JP-5 and JP-8 dispersed at a faster rate over the surface and exhibited a greater propensity for dripping than those of high volatility AvGas and JP-4. Low temperatures, inclined surfaces, and polyurethane latex surface coating enhanced fuel dripping from the test surface. Fuel flow rates required to support sustained burning at the leakage site were investigated with JP-4, JP-5, JP-8, JP-4JP-8 mixtures, and AvGas. The measurements were conducted at temperatures ranging from 3.3 C to 98 C 38 F to 209 F. The vapor pressure of the fuel at the test temperature has a very pronounced effect on the propensity of the leaking fuel to sustain burning. The minimum volume flow rates required for sustained burning ranged from 0.2 mlmin. AvGas at 23 C 73 F to 9 mlmin. JP-5 at 98 C 208 F.