NFF Glossary Definition

No Fault Found (NFF), No Trouble Found (NTF) or No Defect Found (NDF) are terms used in the field of maintenance, where a unit is removed from service following a complaint of a perceived fault by operators or an alarm from its BIT (built-in test) equipment. The unit is then checked, but no anomaly is detected by the maintainer. Consequently, the unit is returned to service with no repair performed.

See also: NFF.

In cross-functional technology work, this term provides background for concepts that support multiple disciplines rather than one narrow specialty. It is relevant when a reader needs a concise explanation that can transfer across business, technical, documentation, or operational settings.