A latent fault that is not apparent until the equipment is asked to perform its function describes which failure type?

• A. Functional Failure
• B. Potential Failure
• C. Hidden Failure
• D. Intermittent Failure

Answer: (C)

When a fault hides in the system until you actually demand the equipment to work, it’s a hidden failure. The fault sits dormant and looks fine during normal checks or idle states, but once the device is asked to perform its function, the fault becomes apparent and can cause incorrect operation or degraded performance. This makes hidden failures especially risky in instrumentation, because routine testing may not reveal them.

In contrast, a functional failure would be evident when you try to perform the function—the device simply doesn’t deliver the required output. A potential failure describes conditions that could lead to a failure in the future but aren’t failing now. An intermittent failure happens irregularly, appearing and disappearing rather than staying latent until use.