During an A-scan test, strong indications that move across the screen horizontally and cannot be repeated by rescanning are most likely caused by:

During an A-scan test, strong indications that move across the screen horizontally and cannot be repeated by rescanning are most likely caused by:

• A. Porosity
• B. Crack
• C. Blow hole
• D. Electrical interference

Answer: (D)

Electrical interference shows up as unpredictable, non-repeatable signals in an A-scan. Real flaws create reflections at a specific depth, so when you rescan the same area with the same setup, those reflections reappear in the same place. If strong indications drift horizontally across the display and cannot be reproduced on rescans, they’re most likely electronic noise rather than actual material discontinuities. To verify, check grounding, shielding, connections, and equipment settings, and retest with stable setup; genuine flaws should remain consistent in position across scans.

Electrical interference shows up as unpredictable, non-repeatable signals in an A-scan. Real flaws create reflections at a specific depth, so when you rescan the same area with the same setup, those reflections reappear in the same place. If strong indications drift horizontally across the display and cannot be reproduced on rescans, they’re most likely electronic noise rather than actual material discontinuities. To verify, check grounding, shielding, connections, and equipment settings, and retest with stable setup; genuine flaws should remain consistent in position across scans.