Breakdown of Preservative Fluid MIL-PRF-46170 in Aircraft Hydraulic Systems

摘要

This document summarized a series of laboratory tests performed to identify material forming on hydraulic system filters of fleet aircraft. Additional information obtained from outside sources is also summarized for background. Laboratory pump testing showed rapid filter dogging with small amounts of preservative fluid (MU-PRF-46l70) in the system. Similar conditions with 100% hydraulic fluid (MIL-PRF-83282) did not clog filters at these rates. Preservative fluid at elevated temperatures showed breakdown, increase in acid number, and chemical attack of test coupons while hydraulic fluid alone does not degrade. Preservative fluid is not compatible with operating aircraft hydraulic systems.