Hydraulic Valve Erosion Investigation -- 727 Elevator Feel Computer Valve

摘要

The report covers progress made in one portion of the investigation into the hydraulic control valve erosion problem encountered on 727 and 737 airplanes. The portion of work presented in this report includes testing with the old design (LTV P/N 401-60547-2) 727 elevator feel computer valve with various hydraulic fluids, filters and 4A molecular sieves. The overall investigation also has included evaluation of other factors such as contamination, cavitation, temperature, fluid acidity, fluid additives, control valve materials, control valve port configuration and system back pressure. (Author)