In this article, a crack detection technique for use in the C130 rainbow fitting is described.  The vibration characteristics of a simplified template of the fitting are characterized first using a scanning laser vibrometer.  EDM notches are then introduced and changes in the full-field vibration patterns as a function of frequency are identified.  Fatigue experiments are then conducted to initiate a crack in the notch and the effects of these actual cracks on the vibration signatures are evaluated.  The effects of the crack are quantified by estimating an equivalent mechanical forcing function, which affects the response measured with a triaxial accelerometer in three orthogonal directions.  It is demonstrated that the quasi-periodic nature of the fitting enables the use of mode localization for crack detection globally using remote measurements acquired in the center of the fitting.  The benefits of multi-dimensional sensing for crack detection are also demonstrated.