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Eddy current jet engine disk-crack monitorA disk-crack monitor is described that is suitable for use on the ground or in flight. The system consists of an engine-mounted eddy current sensor, a series capacitance in each leg of the sensor circuit, and a capacitance-conductance bridge followed by an oscilloscope capable of advanced signal processing. It was applied to the detection of service-induced cracks in the first-stage turbine wheel of a helicopter engine. A 3.5 mm long radial fatigue crack plus smaller cracks, all located in the blade root region of the wheel, were detected during engine test stand operation at ground idle speed and temperature. The calculation of the value of series capacitance is also presented.
Document ID
19850028949
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Barranger, J. P.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 12, 2013
Publication Date
October 1, 1984
Publication Information
Publication: Materials Evaluation
Volume: 42
ISSN: 0025-5327
Subject Category
Instrumentation And Photography
Accession Number
85A11100
Distribution Limits
Public
Copyright
Other

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