Case Analysis & Practical Application Flashcards
7 cards from real CLS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Case Analysis & Practical Application flashcards as text
A lube tech is sampling oil from a turbine that operates at 65°C. The sample is taken when the unit is shut down and the oil temperature has dropped to 25°C. What is the main concern with this sampling approach?
Answer: Contaminants and wear particles settle when oil is cold, making the sample unrepresentative
Particles settle rapidly in cool, static oil, so a cold-oil sample will under-report contamination and wear compared to a sample taken at operating temperature.
A centrifugal pump handling a corrosive chemical slurry has its bearing housing redesigned to use sealed-for-life bearings pre-packed with grease. Six months later failures begin. What is the most probable cause?
Answer: Heat and vibration have degraded the factory grease charge faster than anticipated
Sealed-for-life bearings rely on a fixed grease charge that can degrade under elevated temperatures and vibration, causing premature failure when the grease life is shorter than the intended service interval.
A maintenance team is troubleshooting a hydraulic cylinder that drifts under load. Oil analysis shows the fluid is clean and within viscosity specification. What lubrication-related cause should be ruled out next?
Answer: Cylinder seal wear allowing internal bypass between piston faces
A drifting hydraulic cylinder with acceptable fluid condition points to internal seal bypass, allowing fluid to pass from the high-pressure side to the low-pressure side of the piston.
A plant is considering extending oil drain intervals in its diesel-powered lift trucks from 250 hours to 500 hours. Which approach best supports this decision?
Answer: Using used oil analysis (UOA) data over multiple samples to validate oil condition at 500 hours
Used oil analysis over multiple drain cycles provides empirical evidence of remaining oil life, making the drain interval extension scientifically defensible.
After a bearing failure, inspection reveals a fluted (washboard) pattern on the outer race. Which root cause does this pattern indicate?
Answer: Electrical current passing through the bearing and creating arc damage
Fluting on bearing races is the classic signature of electrical current discharge (EDM), which occurs when stray current arcs through the bearing contact zone.
A lube engineer wants to reduce the number of lubricant SKUs in a plant from 87 to under 30. Which step is most important before consolidating products?
Answer: Map every lubrication point to its OEM requirements and operating conditions before selecting consolidated products
Consolidation must start with a full lubrication point inventory mapped against OEM requirements to ensure no equipment is left with an incompatible or under-performing lubricant.
A steam turbine oil (ISO VG 46, R&O type) shows a ruler oxidation test value of 2.0 mg KOH/g after 18 months in service. The OEM condemns the oil at 2.0 mg KOH/g. What should the lube engineer do?
Answer: Schedule an oil change promptly and investigate the cause of accelerated oxidation
An oil that has reached the OEM condemn limit should be changed promptly, and the root cause of rapid oxidation (heat, aeration, contamination) should be identified and corrected.