Verification test of the structural integrity of an external fuel tank for aircraft under slosh and vibration conditions

Abstract

During operation aircraft, a significant load is applied to the internal components of an external fuel tank due to fuel slosh and engine vibration. Also, in a serious situation, components or pipes may be damaged or may not function properly, adversely affecting not only the safety of the aircraft but also the survival of the crew. Therefore, aircraft components such as an external fuel tank can be installed on an aircraft only when the required structural integrity under sloshing load and vibration conditions is proven through a qualification test. In this paper, a verification test was conducted to prove the structural integrity of an external fuel tank against sloshing and vibration conditions as specified in US military standards. In the main text, the test requirements, slosh and vibration test procedures, and equipment used for the test are explained. In addition, the structural integrity of the test fixture to fix the test specimen to the sloshing and vibration test equipment was checked by performing a vibration analysis. During the slosh and vibration test, the internal pressure and excitation frequency of the test specimen were monitored in real time to check whether the specified test conditions were satisfied. As a result of the slosh and vibration test, the test requirements were confirmed to have been met through an analysis of data from an accelerometer installed on the test specimen and through a leakage check conducted by means of a pressure test. After the test was completed, structural damage and/or leaks of the test specimen were checked by disassembling the test specimen.