22nd Congress of International Council of the Aeronautical Sciences, Harrogate, UK, 28 August - 1st September, 2000
Paper ICAS 2000-6.9.1 (IL)

RECENT EXPERIENCE IN FLIGHT TESTING FOR PILOT INDUCED OSCILLATIONS (PIO) ON TRANSPORT AIRCRAFT

B. P. Lee
Airplane Handling Qualities, Boeing Commercial Airplanes, Seattle, WA, USA

Keywords: flight test, pilot induced oscillations (pio), flight dynamics, handling qualities, stability and control

Though the subject of Pilot Induced Oscillations (PIO) is not new, it has garnered significant attention in the past several years. Since the mid 1990’s, Boeing Commercial Airplanes has been conducting specific flight tests of its products in order to evaluate PIO tendencies. Beginning with the 777-200, a generic suite of test maneuvers has been used to evaluate PIO tendencies on each product. The testing has been conducted on a “window of opportunity” basis with the intent to gather data and evaluate each model. To date, specific evaluations have been carried out on six different airplane models spanning a wide range of airplane sizes, inertial characteristics, and control system implementations. Each maneuver in the generic suite is discussed in detail. In addition, along the way, a large number of other maneuvers have been used at various times to evaluate PIO tendencies. These are briefly described. No single test maneuver or technique has been identified which provides effective discrimination of PIO tendencies. Finally, the subject of the pilot in the loop is discussed with regard to achieving consistency in conducting PIO evaluations.

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