Development Flight Test Campaign for Automatic Flight Control System

T-625 Gökbey is a light utility helicopter developed by Turkish Aerospace Industries since 2013. For T-625, automatic flight control system performance evaluation and development test campaign was conducted. In this paper, test campaign is investigated thoroughly. To assess and quantify the automatic flight control system performance and handling qualities, various different metrics and specifications were selected. This metrics covered both time and frequency domains. After metric selection, a set of test points were created. Most of the test points required delicate piloting and were easy to fail. Furthermore, a large flight envelope in terms of altitude and air pseed was needed to be covered. Hence, both test point number and required flight time estimates were very large. Hence, to not further increase flight time and need of test point repetitions, various different precautions were taken, such as using computer generated sweeps. While conducting tests, altitude kept constant while speed envelope tested. Then, altitude were changed to a new value and speed envelope is tested again. After each sortie, flight data were analyzed whereas control parameter updates were performed after finishing tests for all airspeed values for an altitude. After control parameter updates, validation tests were done to ensure that updated parameters provided expected performance. At this point, most of the test campaign is done and selected specifications were met for almost all the tested flight envelope.