Controlling the Hazard of Hydraulic System Contamination in U.S. Army Helicopters

摘要

Hydraulic flight control systems of rotary wing aircraft are flight critical in that some of their failure modes can result in loss of control of the aircraft, leading to catastrophic loss of the aircraft and its occupants. In particular, sensitive hydraulic components such as actuator valves, cylinders, and pumps can fail as a result of moisture, particulate, or chemical contamination in the hydraulic fluid. The investigations following a few significant accidents involving U.S. Army helicopters suggested, though never proved conclusively, that hydraulic fluid contamination might contribute to the potential for helicopter accidents. Regardless of whether or not contamination actually played a role in past accidents, the Army determined that more attention needed to be given to minimizing the risk of aircraft accidents from hydraulic system contamination. In 2000, the Army chartered an integrated process team (IPT) to gain a better understanding of the hydraulic system contamination hazard, develop an appropriate and cost-effective contamination control program, and implement the program across the units that maintain and fly its modern fleet of scout, attack, utility, and cargo helicopters. This paper gives a detailed explanation of the hydraulic system contamination hazard, and summarizes the results of the Army’s data collection efforts and its accomplishments toward developing and implementing the hydraulic system contamination control program.