VIBRATION TESTS FROM A TURBOPROP ENGINE AND AIRSCREW OF A SMALL TRANSPORT AIRCRAFT

During the initial operation of the prototype of the airliner, an increased level of vibration was observed, which originated from the turboprop engine and propeller and was transferred to the engine-mounting frame and the airframe. These vibrations caused an increased noise level and increased force level in the mounting frame and the airframe, as well as reduced the comfort of passengers and crew during the flight. Tests on the vibration level of the aircraft structure were performed in various operating conditions and engine loads. Vibration tests of the engine-mounting frame were carried out in the engine operating conditions on the ground, in flight at different heights and during the landing of the aircraft for different flap deflection values. The analysis of the results was done using Fast Fourier Transformation (FFT). The results of the analysis are illustrated graphically. The paper presents only the elements of the flight, in which the amplitude of the force was observed. An analysis of the results obtained was performed to determine the actual dynamics of forces in the frame fastening the engine to the airframe during all elements of the flight.