Propulsion system safety analysis methodology for commercial transport aircraft

摘要

Airworthiness certification of commercial transport aircraft requires asafety analysis of the propulsion system to establish that the probability of afailure jeopardising the safety of the aeroplane is acceptably low. Theneeds and desired features of such a propulsion system safety analysis arediscussed, and current techniques and assumptions employed in suchanalyses are evaluated. It is concluded that current assumptions andtechniques are not well suited to predicting behaviour of the propulsionsystem in service. The propulsion accident history of the high bypass ratiocommercial transport fleet is reviewed and an alternate approach topropulsion system safety analysis is developed, based on this accidenthistory. Features of the alternate approach include quantified prediction ofpropulsion related crew error, engine-level reliability growth modelling torealistically predict engine failure rates, and quantified credit for designfeatures which mitigate the effects of propulsion system failures. Thealternate approach is validated by applying it to two existing propulsionsystems. It is found to produce forecasts in good agreement with serviceexperience. Use of the alternate approach to propulsion system safetyanalysis during design and development will enable accurate prediction ofthe expected propulsion related accident rate and identification ofopportunities to reduce the accident rate by incorporating mitigatingfeatures into the propulsion system/ aeroplane design.