FLIGHT TESTING THE HANDLING QUALITIES REQUIREMENTS OF ADS-33C - LESSONS LEARNED AT ATTC

The U.S. Army Aviation Technical Test Center (ATTC) has conducted numerous evaluations of rotorcraft handling qualities using the proposed updated MIL-H-8501 requirements contained in ADS-33C, Handling Qualities Requirements for Military Rotorcraft. Tests were conducted on the AH-64A and OH-58D helicopters; the Bell Helicopter Textron Inc./ McDonnell Douglas Helicopter Company and Boeing/Sikorsky Light Helicopter (LH) simulators. The AH-64A and the OH-58D were used as examples of present day state of the art aircraft to evaluate the adequacy and testability of ADS-33C, even though neither aircraft were designed to its rigorous requirements. The tests conducted on the AH-64A served to validate the requirements of the new specification and to refine the flight test techniques that will be utilized during future flight test programs. A demonstration of frequency domain flight testing techniques and analysis was performed on an OH-58D helicopter. Bandwidth and phase delay parameters were determined from flight test data according to the definitions in the ADS-33C and compared with actual handling qualities. Some lessons learned during handling qualities testing of ADS-33C are addressed. In general, the ADS-33C provides a useful guide to evaluate an aircraft’s handling qualities.