Abstract: An ultrasonic calibration block for standardizing an output of a pulse-echo ultrasonic inspection system is provided with an insonification surface for receiving ultrasonic pulses from the inspection system and a plurality of reflective interfaces stacked on top of one another and positioned at different distances from the insonification surface, each reflective interface having a different and characteristic reflectivity. A method of calibrating the output of the inspection system, using the calibration block, employs standard waveforms generated by insonifying the calibration block to generate a look-up table of standard waveform amplitudes related to a standardized output of the inspection system for a given material of a part to be inspected.

Abstract: An automated eddy current fastener hole inspection apparatus and method for providing an automatic indication of the presence of a crack in structural members. The device automatically advances the probe of an eddy current instrument in a hole in the structural member, induces an eddy current, detects the eddy current signal produced by the eddy current instrument, digitizes the eddy current signal, analyzes the digitized signal for the presence of a characteristic signature corresponding to the effect of a crack in the structural member upon the eddy current signal, and alerts the operator of the presence of a crack or of noise conditions in the eddy current signal which may mask the presence of a crack. The device is responsive to contiguous repetitions of the characteristic signature of a crack within predetermined time windows to distinguish between data corresponding to a bona fide crack in the structural member from data produced by the effect of noise, dirt, grease, etc. upon the eddy current signal.

Abstract: The inspection of a portion of an internal member of an assembled article, unavailable for direct line inspection, for example portions of the rotor of a gas turbine engine, is accomplished through the use of an ultrasonic probe inserted through an access port of the article toward a surface of the member to be inspected. As a result of predetermined positioning of a transducer in the operating head of the probe to bounce an ultrasonic signal from an internal boundary toward the portion to be inspected and the comparison between predetermined and received signals, along with an analysis of the comparison, determines whether a defect is present in the member.

Abstract: Disclosed is a means and method for evaluating a bond between first and second structures bonded together by an intermediate layer of adhesive. Means are provided for transmitting a pulse of ultrasonic wave energy into the bonded structures whereby a first reflected pulse may be reflected from a first surface of the first structure, a second reflected pulse reflected from the layer of adhesive, and a third pulse possibly reflected from the surface of the second structure adjacent the adhesive layer. Circuit means are provided for sensing the first, second, and third reflected pulses and for providing an indication of the quality of the bond by comparing the amplitudes of the reflected pulses and determining if the ratios lie within predetermined ranges.

Abstract: Disclosed is an apparatus and method for evaluating a bond between first and second structures bonded together by an intermediate layer of adhesive. Apparatus is provided for transmitting a pulse of ultrasonic wave energy that has a duration at least as short as 1.5 wave cycles into the bonded structures whereby a first reflected pulse may be reflected from a first surface of the first structure, a second reflected pulse reflected from the layer of adhesive, and a third pulse possibly reflected from the surface of the second structure adjacent the adhesive layer. Circuits are provided for sensing the first, second, and third reflected pulses and for providing an indication of the quality of the bond by comparing the amplitudes of the reflected pulses and determining if the ratios lie within predetermined ranges.