The Hellenic Air Force (HAF) operates both EMB-145 and EMB-135 LR versions of Embraer aircraft, used in surveillance and civil missions respectively. These aircraft are equipped with the same version of Rolls Royce, AE 3007 turbofan engine. This study aims to quantify and compare the life consumption rate of this engine when installed in each of the two aircraft variants. Two typical missions, one for each variant, were constructed based on mission profile data dictated by the aircraft commanders. For each mission profile segment, corresponding engine data were matched out of the engine recordings archives held by the Hellenic Air Force. The life consumption rate was based on the Low Cycle Fatigue (LCF) and creep cumulative detrimental effect on the rotor blades of the 1st High-Pressure Turbine stage. For the LCF, the rainflow method was used to determine the respective loading cycles, whereas the Larson - Miller parameter method was used to determine the consumed life fractions due to creep. The main conclusion of the study was that the engine when installed in the EMB-145 military variant, is much more loaded. Despite the fact absolute life consumption values could hide a great level of uncertainty, the comparative outcomes wherein errors are, to a certain extent, cancelled out, could be used as a rule of thumb when monitoring engine life consumption rates.
Geoid undulations reflect density contrasts within Earth. In this study we show that many features known from other geophysical sources, such as gravity and magnetic anomaly maps, tectonic and geological maps, are also discernible in an accurate geoid. This suggests an association between these features and density anomalies. To demonstrate the usefulness of the geoid for geophysical interpretation we have chosen to use the “terrestrial contribution” to the UNB Dec. '86 Canadian geoid. This is a high‐resolution shorter wavelength (of degree and order higher than 20, or half wavelength less than 1000 km) part, which is readily available as a natural product of the geoid compilation when the UNB formulation of the geodetic boundary value problem is used. To facilitate the recognition of different features we have employed different image enhancement techniques. Hill shading combined with hypsometry (color coding of heights) appears to be the most promising in our context.
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