Air Force C-130 Rainbow Fitting Diagnostic Technology Development

The C-130 Hercules has been a workhorse for the U.S. Air Force for decades and is projected to continue to accrue flight hours for years to come as a highly capable platform utilized for numerous mission profiles. In the past few years, many C-130 aircraft have developed fatigue cracks in the center wing box rainbow fittings. These cracks can be a significant flight safety risk, when the damage is extensive. In order to detect the existence of cracks in the rainbow fittings so that they can be repaired, implementation of labor intensive eddy current nondestructive inspection technology has been used to assess the condition of each aircraft on a scheduled basis. The Air Force is interested in the development and application of alternative fault detection techniques that are less time demanding to implement by the maintainers, while providing a high damage detection probability. Additionally, the future capability to embed effective rainbow fitting fault detection capability into the aircraft as an integrated systems health management (ISHM) solution is also desired.