REFERENCE-STANDARDS - VITAL CONTROLS IN AIRCRAFT ULTRASONICS

Nearly every ultrasonic NDT inspection carried out in the aerospace ma intenance industry is preceded by a calibration procedure which uses a test block or to give it the more modern term, Reference Standard. Th e Reference Standard is aptly named, as it does truly 'set the standar d' and is fundamental to the integrity of the inspection. In the past, the importance of the Reference Standard was recognised by controllin g the manufacture of blocks and comparing new ones against a 'master' held in the maker's laboratory. Sadly this practice is no longer commo n, being considered impractical in today's world, it is all the more i mportant, then, that the primary role played by the Reference Standard should be remembered and recognised by those in the industry.