Implementation of damage tolerance requires the characterization ofnondestructive evaluation (NDE) capabilities in terms of the probability ofdetection as a function of flaw size. Quantification of NDE procedures isessential to provide both a confidence level in detection of required flawsizes and in establishing periodic inspection / maintenance events as afunction of part usage. Gas turbine engine components (aircraft engines) arehighly loaded and critical the safe-life / operation of an engine. Ingeneral, detection of small flaws is required to provide the maximum meantime between inspection cycles and thus contribute to most economical engineoperation.Reliable detection of small flaws in engine components has been demonstratedby precision eddy current inspection procedures. The procedures wereimplemented using a precision robotics scanner and various eddy currentprobes and scanning sequences. The eddy current system elements wereintegrated into scanning sequences to provide a quantitative, fullyautomated inspection of critical areas of engine components. The integratedsystem is identified as the RFC (Retirement for Cause) system and has beenextensively applied to the inspection of rotating gas turbine enginecomponents throughout the world.Since the introduction of the system in 1979, additional engine componentsand inspection features have been added to provide support of variousengines and to extend the life of aging components. The most recent systemimprovements have been an improved eddy current instrument, an improvedrobotics controller and added computing and electronic communicationscapabilities. This paper described the retirement for cause systemmanagement principles; the RFC eddy current system development andapplication; and the recent improvements to increase capabilities and reduceboth system cost and system operating costs.
展开▼
