Requirements for Designing A Robotic System for Aircraft Wing Fuel Tank Inspection

An aircraft wing is built up of complex subassemblies including rib and spar structures, fuel transfer holes, piping and electronical wiring bundles. The wing structure is also used as storage space for the jet fuel in the ‘wet wing’ configuration. Vigorous inspection procedures are in place to detect defects such as fuel leaks, microbiological initiated corrosion and impact damages. Inspection inside the wing is significantly challenging due to the physical complexity, restricted accessibility and presence of fuel vapour. Current literature has highlighted opportunities for a novel aircraft fuel tank inspection robotic system. This paper starts with an overview of existing maintenance practices with the use of Remote Visual Inspection (RVI) equipment for fuel tank inspection, highlighting the implications and challenges of these methods. Their limitations inspire the development of novel robotics to achieve detailed internal inspection of an aircraft wing fuel tank. This research investigates the challenging case of fighter aircraft wing tank inspection. The wing shape geometry is highly irregular with very few fixed cartesian reference points. The internal structure is congested with many systems and difficult to manoeuvre within. This paper summarises the key requirements for inspection robotics for this particular case study. The requirements are presented in three categories; Robotic locomotion and navigation imposed by the complex and confined space inside the wing structure, secondly the materials, mechanisms and power sources imposed by the hazardous and potentially explosive environment inside the wing tank and lastly, the inspection sensors and assessment algorithms imposed by fuel tank defect and degradation features. The authors focus on the robotic system flexibility and mobility challenges to overcome the numerous obstacles within the confined space whilst effectively integrating a visual inspection technique to capture defined defects. This paper builds on the limitations of current inspection methods to elaborate the requirements for a robotic system to carry out inspection of fighter aircraft wing fuel tank, typical of challenging harsh environment.