Read the passage about turbine engine lubricants and complete the logical conclusion regarding lubricant testing.
Answer:Aircraft turbine engine lubricating oils must maintain stable viscosity across extreme operating temperatures. Synthetic ester-based oils resist thermal breakdown at elevated temperatures, preventing sludge accumulation. However, when contaminated with atmospheric moisture over time, ester molecules undergo hydrolysis, splitting into organic acids and alcohols that accelerate bearing corrosion. Therefore, maintenance technicians evaluating degraded turbine oil test not only for viscosity changes, but primarily for increasing 【acidity】 levels.
Answer
acidity (or acid / organic acid)
The passage establishes that moisture causes ester oil molecules to undergo hydrolysis, splitting into organic acids and alcohols. Because these organic acids accelerate bearing corrosion, testing for increased acidity directly detects whether moisture-driven chemical breakdown has occurred.
Step-by-Step Solution
Key Concept
Drawing logical conclusions from cause-and-effect relationships in technical passages