Load factor (NZ) / Roll rate: First comparisons between design and in-flight recorded data on eurofighter typhoon italian fleet

Abstract

In order to monitor the Eurofighter Typhoon fatigue life and allow an efficient fleet management, the Structural Health Monitoring (SHM) system is currently being used to register a large quantity of flight parameters that influence life consumption, or simply characterize the usage of every single aircraft. Furthermore, synthetic fatigue parameters are also calculated by the system in order to monitor fatigue life associated to any single flight. This amount of flight and fatigue data is being collected and stored in a data base developed for the scope. As the number of monitored flights increases, data stored within the database become more and more able to represent the effective usage of the fleet. Actually, increasing the number of aircrafts operated by Italian Air Force, the amount of data available in the database is becoming significant to perform first studies. A further feature of the SHM system, in conjunction with the data base, is to allow focusing on the analysis of some specific aspects of aircraft usage, such Load Factor (Nz) occurrences, altitude cycles, airbrake usage, etc. Hence, also considering the increasing amount of data being managed by the database, it's becoming interesting to perform some early analyses to compare "design" and "in flight recorded" data. The aim of this paper is to present a comparative analysis between design and in-flight registered data, performed on the Load Factor (Nz) coupled with Roll Rate data. During every single monitored flight, the on-board Structure Health Monitoring (SHM) system registers the number of occurrences of pre-established combinations of Load Factor (Nz) and Roll Rate values. Occurrences of these values belonging to the already analyzed monitored flights have been collected, analyzed and compared to the design values. In this way it is possible to analyze the in-flight behaviour in terms of symmetric and asymmetric manoeuvres. Specific investigations have been conducted upon roll rates distribution and asymmetric manoeuvre segments. © Springer Science+Business Media B.V. 2009.