scope:

Introduction: Removals of equipment from service for reasons that cannot be verified by the maintenance process (shop or elsewhere) are a significant burden for aircraft operators. This phenomenon is commonly referred to as No Fault Found (NFF).

Many other industry guidelines have been created in the past addressing NFF. NFF is often perceived as a shop-only problem or an individual component reliability problem. This is not true. NFF solutions require an inter-disciplinary effort to identify the true causes and implement successful solutions.

This document describes the most common sources of NFF and provides guidance to develop appropriate solutions. The sources of NFF are spread throughout the following four domains:

•Design/Production

•Flight operations

•Line operations

•Shop operations

This report provides a holistic view of the NFF problem based on the above domains and the following categories:

•Documentation

•Communication

•Training

•Testing

•System/Components design

Complete elimination of NFF is not a realistic expectation. However, a structured approach will help toward minimizing the effects of NFF.