In immersion testing, false indications caused by contoured surfaces are most likely to appear as which type of indication?

• A. Broad based indication
• B. Peaked indication
• C. Hashy signal
• D. Narrow based indication

Answer: (A)

When a surface is contoured, the ultrasonic energy reflects from many slightly different points along the curve rather than from a single flat plane. This causes echoes to arrive over a spread of angles and times, so the response on the display looks smeared rather than concentrated. In practice this shows up as a broad-based indication—a wide, diffuse echo that’s not tied to a single sharp reflector. A peaked indication would suggest a more localized flaw, a hashy signal indicates random noise, and a narrow based indication points to a very localized feature. Hence, a broad-based indication is the most likely false indication from contoured surfaces.