No fault found
TERM USED IN TECHNICAL MAINTENANCE
No Trouble Found; No Defect Found; Draft:No Fault Found; Fault not found
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.