Flight Testing Amateur-Built Helicopters

Test-flight procedures for the amateur-built helicopter are presented. Test methods were acquired from acceptable practices for flight testing Normal Category Rotorcraft, Amateur-Built Aircraft and Ultralights. These acceptable practices were modified to overcome the challenges faced by the amateur-built helicopter test pilot. These challenges include limited in-flight instrumentation. A significant modification of procedures was to establish a methodology of flight testing using collective control stick position as an indicator of power during performance testing. Additionally, this procedure provides a method structured to overcome limited instrumentation during testing of stability and control. In-flight test data of a United States Army OH-58 was used to verify the relationship between collective position and engine shaft horsepower required (ESHP_req) could be used to provide a means of estimating power usage. Percent of collective stick position and ESHP_req required were 'reduced' and analyzed. It is concluded the curves developed by plotting percent collective position were similar to ESHP_req curves in the speed range of interest (below 90 knots) and allow for acceptable practices of data reduction to be employed using percent of collective stick position. The recommendation is that these test methods be adopted by the Experimental Aircraft Association (EAA) for supervised field-testing of amateur-built helicopters with limited instrumentation.