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Issue link: http://amt.epubxp.com/i/679617
EASTMAN AVIATION SOLUTIONS AIRLINE 10 MAY 2016 AIRCRAFT MAINTENANCE TECHNOLOGY through higher thermal stability These HPC oils have been designed to handle the requirements of newer more fuel-efficient engines that typically have higher operating temperatures. APU oils are typically slightly thinner oils (3 cSt) so they offer better low temperature properties to support engine start/stops in colder environments because of the ability to function in cold temperatures which is essential for extended-range twin-engine operations (ETOPS) when a cold start is required by the APU. Additionally, for the helicopter market there are 5 cSt oils offering enhanced load-carrying features supporting use in combined engine/gearbox lubrication systems. AMT: What are some key indicators of a healthy oil system? PF: When a commercial aircraft engine consumes sufficient HPC oil through normal operation and subse- quent top-off, regular oil testing is generally not neces- sary. Oil analysis is seldom employed in commercial airline operations. However, operators of turbine engine helicopter, business and general aviation aircraft will still perform regular testing as the original charge of oil may well be in the oil system for much longer periods without top-off. Modern engines also have on-board systems to detect metallic wear chips in the oil system as well as sensitive accelerometers to detect vibration due to bearing deterioration that will alert operators to an issue faster than any practical oil sampling interval. Considering oil health over an extended time period, its quality and performance features are generally pre- served through normal top-off frequency (typically 0.1 quarts per operating hour). This situation is different in lower utilization segments such as some helicopters and general aviation aircraft where the lubrication system has the opportunity to accumulate moisture during periods of inactivity as well as lesser opportunity for refreshing of the oil charge through top-off replenish- ment. Ultimately, this lack of aircraft utilization can accelerate the deterioration of the turbine oil. AMT: What benefits are operators likely to see when transitioning to the new HPC technology lubricants? PF: Various engine models require specific lubri- cation system component inspections and cleaning LEFT: SUMP bearing operating on SPC. RIGHT: NOTE the cleanliness of this sump bearing when using HPC oils. EASTMAN AVIATION SOLUTIONS TURBINE ENGINE oils undergo rigorous chemistry testing to ensure they perform to today's demanding requirements.