This report describes the work conducted by TUD for WP 4.2.7 of the ESPOSA project for the development of Gas Path Analysis (GPA) based Engine Health Monitoring (EHM) concepts for the BE1 and BE2 engine designs. Models developed with the Gas turbine Simulation Program GSP have been used for the development and for the simulation of deteriorated engine data. A comprehensive differential GPA concept is demonstrated and feasibility assessed assuming sufficient sensor data can be obtained from the BE1 and BE2 engines during operation. The concept is based on the Adaptive Modeling capability of GSP. With differential GPA, engine condition can be determined on the component level, offering significant potential to optimize the maintenance concept and minimize maintenance costs. However, in the current design of the BE1 and BE2 engines, less than sufficient data are measured. Therefore differential GPA can only be applied after more sensors are added which in turn means extra costs. At this stage, the trade-off between extra costs and benefits cannot be made. For small, low cost engines like the BE1 and BE2, additional sensors are relatively expensive. As a consequence, a parametric performance monitoring GPA concept has been developed and demonstrated instead, still offering significant benefits for the maintenance concept. Baseline functions have been defined for reference engine performance to which operational data can be compared. From the deviations conclusions can be drawn w.r.t. engine condition and to a limited extent also gas path component condition. The GSP project for demonstrating differential GPA and the performance monitoring concept is provided separately in digital format with the file Eposa_D1331_BE1_GPA_rev2.0.mxl.