This is the second half of a two paper series covering aspects of the no fault found (NFF) phenomenon, which is highly challenging and is becoming even more important due to increasing complexity and criticality of technical systems.
Terms used to describe this phenomenon include trouble not identified (TNI), no trouble found (NTF), cannot duplicate (CND), 're-test ok' (RTOK), no-fault found (NFF), and intermittent malfunctions.
Preliminary results indicate a reduction in the number of sub-unit inspections required for isolation of all faults and the number of no fault found cases.
To create industry awareness, we demonstrate two examples out of an OEM driven study on mechanical induced parametric deviations which relate to corresponding product verification/validation issues that can end up in real, but which are mostly classified as no fault found (NFF) issues.
"Of these, some had physical (transit) damage and others had no fault found, so the actual figure is somewhat lower again," he adds.
No fault found (NFF) No particular root cause was found for 87 door defects (i.e. 42.4 % of the total door defects reported).
If you had a test, and there's no fault found as it were, it would be nice to have that confirmed.
(Phase I: Patient 1, Practice 4) If you had a test, and there's no fault found as it were, it would be nice to have that confirmed.
The battery did not explode and no faults were found in the design of the safety system.
Also, the report said no faults were found with the transmission or rotor system, there was no evidence of structural failure or in-flight fire and no evidence of damage caused by bird strike or a foreign object hitting the aircraft in flight.
The agency no longer found fault with the MCRC's methods for determining the route of the proposed road, but reaffirmed its objection to how the road commission's plan would minimize impacts to wetlands and streams.
