Comparison between reliability, sensitivity and accuracy of non-destructive inspection methods

Comparison between reliability, sensitivity and accuracy of non-destructive inspection methods

de Graaf, E.A.B.
de Rijk, P.

National Aerospace Laboratory NLR

1981-03-31

The concepts of reliability, sensitivity and accuracy of non-destructive inspections are defined. Next is an explanation of the limitations of repetitive use of NDT-rellabi1ity specimens followed by a comparison between the inspection results of fluorescent and red penetrants. Subsequently the paper deals with reliability, sensitivity and accuracy of a number of inspection methods in frequent use. They are applied to one hundred aluminium specimens fabricated purposely by the NLR, as well as to more than 220 rejected steel components of real aircraft undercarriages. It will be shown that there exists a fair amount of scatter between the results of different techniques and inspectors and also between subsequent inspections by one inspector. It is obvious that corrosion has a significant influence on all three aspects of NDT mentioned in the title. The results of the ultrasonic inspections turn out to be rather disappointing, whereas the results of penetrant inspections tend to depend rather heavily on the specimen configuration. Fluorescent penetrant performs far better than red penetrant, Eddy current gives good moderate results. On the steel components fluorescent magnetic ink as well as magnetic rubber achieve by far the best results, at the penalty of a fair amount of spurious indications.

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Nationaal Lucht- en Ruimtevaartlaboratorium

Campus only

NLR MP 81009 U

Aerospace Engineering Reports

report

(c)1981 National Aerospace Laboratory NLR