Nondestructive Taper-Lok Fastener Hole Inspection Without Fastener Removal for Thick, Multi-Layer Structures

The ability to detect cracks within Taper-Lok fastener holes associated with thick, multi-layer wing structures without removing the fastener presents significant challenges to existing nondestructive inspection technologies. Critical fastener hole inspections for sections of the B-1B wing structures require removal of the Taper-Lok fasteners followed by eddy current inspection, at a cost projected at $1 million per aircraft. These widely-deployed aircraft have been facing unanticipated near-term fatigue inspections of flight critical areas on the wings and wing carry through locations due to extensive operations beyond predicted. A new, advanced Nondestructive Inspection technology, Photon Induced Positron Annihilation (PIPA) has demonstrated the capability for thick, multi-layer damage detection and could enable rapid, low-cost inspection of B-1B wing structures without removal of the Taper-Loks, limiting risk to the aircraft structure. PIPA is capable of multi-layer analysis and measurement of fatigue, pre-cracking, and micro-cracks in metal alloys at a much earlier stage and with far better accuracy than any other technology, and can perform in-situ measurements on otherwise inaccessible structures, such as the multi-layer B-1B wing configuration. The basis for this project is to validate Positron Systems' new material inspection technology to detect operational fatigue damage in representative B-1B wing splice configurations.