Environmental Influences on Engine Performance Degradation

Abstract

Environmental influences have an increasing effect on the performance degradation and durability of modern aircraft engines. The study provides information on environmental effects using in-flight engine data and results of engine overhauls performed at MTU Maintenance. According to these investigations global regions are classified into erosive and anthropogenic polluted areas. Both types of regional effects significantly degrade performance and engine durability. The investigation, which is based upon the in-flight data taken from Engine Trend Monitoring (ETM), provides one approach for the estimatation of environmental effects on aircraft engine performance degradation. The results of the monitored engines provide detailed information on the environmental effects atlocal airports. The Exhaust Gas Temperature (EGT) that has been measured under flight conditions is compared with a calculated EGT of a calibrated fully thermodynamic gas path engine model (MOPS). Therefore, the EGT also serves as an indicator for performance degradation, increase of specific fuel consumption and the need for on-wing maintenance actions. Further information provided by the engine shop visit data at MTU Maintenance allows for an estimation of environmental influences on durability and overhaul costs. The on-wing time of maintained shop visit data is compared with a model for on-wing time calculation, whereas variations in durability were observed and analyzed under the aspects of environmental influences. Depending on the variations, corrections were made by defining the factors contributing to the classifications of environmental effects. These corrective factors provide information on reduced durability and increased operating costs. The result of the ETM performance degradation analysis shows significant variations in engine performance degradation as a result of specific regional operation. The analyses of maintenance data as well as performance degradation measured by ETM show remarkable environmental effects on engine durability and an increase in maintenance costs.