Aircraft Preventive Diagnosis Based on Failure Conditions Graphs

Abstract

Modern aircraft are designed to be fault-tolerant. Current maintenance systems provide diagnosis of existing faults, capabilities to do trend monitoring, but no information about the real-time remaining tolerance margin knowing the existing faults, and regarding next incoming MMEL (Master Minimum Equipment List) items that impact aircraft dispatch capabilities.
This paper presents a new concept of aircraft preventive diagnosis based on failure conditions graphs with the associated logical framework. The complete method was successfully applied by Airbus on A380 use cases. The first part of the present paper gives the formal logical definitions for the aircraft preventive diagnosis and remaining margin, distance, risk rate. The second part gives an application example based on the landing gear system of an aircraft and also the lessons learnt from Airbus on A380. Finally, the last section provides a logical integration of preventive diagnosis with prognosis that opens new perspectives.