ET-Arrays for NDT of Challenging Bolt Holes

Some US fleets are flying at increased risk and readiness is being substantially impacted by shortfalls in current bolt hole eddy current (BHEC) capability which is not providing sufficient performance. Performance shortfalls include unacceptably high rates of false positives, the occurrence of uninspectable holes, and the size of cracks that can be reliably detected. BHEC performance can further be hampered by edge burrs, gouges, rifling, steel contamination, poor machining, service induced threading, out of roundness, corrosion pitting, and other hole conditions. Prior SBIR programs have demonstrated a significant potential to use JENTEK’s MWM-Array eddy current sensor arrays to provide improved BHEC performance. This program will focus on maturing adaptations of JENTEK’s MWM-Array bolt hole solutions. Particular attention will be given to very small holes (3/16 in. diameter) and holes with layers of substantially different material (e.g., a titanium alloy layer on an aluminum alloy layer). Performance studies will demonstrate the capability of the technology for 3 hole sizes / material layups. The program will deliver a kit for inspecting holes from 3/16 in. to slightly over 1/2 in. in diameter. This kit will be suitable for use with previously delivered JENTEK jET impedance measurement systems.