Loss of Back Reflection (Ultrasonic) : Absence of or a significant reduction of an indication from the back surface of the article being inspected. (RP 2X, RP 5A5)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}