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The United States Army Aviation Engineering Flight Activity supported a contractor engineering effort to correct the nose-down pitch-over during takeoff and the large, variable position error in the low-speed flight regime of the UH-60A (Black Hawk) helicopter. A Preliminary Airworthiness Evaluation was then conducted with the improved airspeed and stabilator systems in their final configuration as defined by the contractor. Handling qualities and airspeed system characteristics were evaluated for two modified overhead and one nose probe configuration. In addition, airspeed system tests were conducted on a second nose probe configuration. Four shortcomings applicable to the modified overhead probe systems were identified as follows: (1) the annoying longitudinal control, stabilator angle, and indicated airspeed reversals resulting in pitch attitude oscillations during takeoff (upgraded from a deficiency in the standard production aircraft); (2) the high pilot workload required to maintain precise airspeed during transitions to high power, low airspeed climbs; (3) the large, variable airspeed position errors; and (4) unreliable airspeed indications in low airspeed, high power climbs. For the modified overhead probe systems the following should be accomplished: (1) evaluate the proposed installation on the External Stores Support System UH-60 helicopter, and (2) evaluate the proposed installation on an extremely light gross weight UH-60 helicopter. |
