The Problem of Cavitation Erosion in Aircraft Hydraulic Systems: A description of an unexpected problem encountered with the Trident hydraulic systems and the steps taken to find a solution

Despite the most thorough testing, both on experimental rigs and in prototype flight trials, the hydraulic systems of the first Hawker Siddeley Trident to go into service with B.E.A. developed internal leaks which seriously affected aircraft maintenance. Investigations showed that seepage was occurring at jack valves, which were suffering from erosion The hydraulic fluid used in the systems was Skydrol 500A, selected as a fluid already in use on a world‐wide basis for the safety inherent in its fireproof properties. This fluid had not been known to induce erosion in other aircraft. After almost a year of intensive research the makers of the aircraft, with the help of hydraulic components manufacturers, found the source of this apparent anomaly. The result of the investigation here described will benefit the designers and operators of hydraulic systems in general.