Engine Lubrication Systems practice questions

Answer: C) Remove air from returning oil

• AIncorrect. That isn't done in turbines.
• BIncorrect. Air in oil is undesirable.
• CCorrect. Air-laden oil pumps and lubricates poorly.
• DIncorrect. That's a probe.

Answer: D) Traps steel particles

• AIncorrect. A relief valve does that.
• BIncorrect. It does not measure viscosity.
• CIncorrect. This is not its function.
• DCorrect. Its magnet attracts steel particles that signal internal wear.

Answer: B) Return oil is foamy

• AIncorrect. Scavenge pumps return oil.
• BCorrect. Scavenged oil contains air and expands, so more capacity is needed.
• CIncorrect. This is not the reason.
• DIncorrect. This is not the reason.

Answer: B) Crankcase pressure builds up and can force oil out past seals and gaskets

A frozen breather traps blow-by gases, so pressure builds in the crankcase. That pressure can force oil out past seals and gaskets, so breather lines need special attention in cold-weather operations.

• AIncorrect. Piston ring blow-by keeps adding gas to the crankcase. With the vent blocked, the crankcase is pressurized, not put under vacuum.
• BCorrect. With the breather frozen shut, blow-by gases have no way out. Crankcase pressure rises and can push oil out through seals, gaskets or the filler and dipstick openings.
• CIncorrect. A blocked breather stops vapor flow out of the crankcase. It doesn't send vapor into the carburetor, and carburetor icing has a different cause.
• DIncorrect. A blocked breather raises crankcase pressure instead of starving the pump inlet. The main danger is oil being forced out of the engine.

Answer: D) In the engine's crankcase sump

• AIncorrect. Oil and fuel are separate.
• BIncorrect. That's dry sump.
• CIncorrect. That isn't oil storage.
• DCorrect. Dry-sump systems use a separate tank.

Answer: A) Shortly after engine shutdown, while the oil is still warm and well mixed

Take oil analysis samples shortly after shutdown while the oil is warm, so suspended wear particles are well mixed. Samples taken this way consistently give comparable results for trend monitoring.

• ACorrect. Right after operation, wear particles are still evenly suspended in the warm oil. The sample then reflects what was circulating through the engine.
• BIncorrect. Once the oil cools and sits, particles settle out of suspension. The sample would then understate the wear metals actually in the system.
• CIncorrect. Settled sediment at the drain would concentrate particles and give a misleadingly high, inconsistent reading that cannot be compared with earlier samples.
• DIncorrect. Unmixed fresh oil dilutes the wear-metal concentration. The sample would not match the oil actually circulating in the engine and would distort the trend.

Answer: B) Concentrations of wear metals in parts per million, trended over time

SOAP burns an oil sample and uses a spectrometer to measure elements such as wear metals in parts per million. Tracking these readings over time reveals developing internal wear before it shows up as large debris.

• AIncorrect. Large particles are found by cutting open and inspecting the filter or screen, or by a chip detector. SOAP analyzes microscopic particles suspended in the oil.
• BCorrect. The sample is burned in an electric arc, and a spectrometer identifies each element and its amount in PPM. A rising trend in a given metal can signal wear in a particular component.
• CIncorrect. Viscosity is a physical property tested by other methods. Spectrometry identifies chemical elements.
• DIncorrect. Oil consumption is found by tracking oil added against operating time, not by analyzing an oil sample.

Answer: A) The additive packages in the two brands may be chemically incompatible

Synthetic turbine oils from different brands can have incompatible additive chemistries, so only brands approved by the engine manufacturer should be mixed.

• ACorrect. Brands that meet the same specification can still use different base stocks and additive chemistry. Mixing them can upset that balance, which is why engine approvals list specific brands and why the effects of mixing have to be shown.
• BIncorrect. Separating into layers is not the reason. The concern is how the additive chemistry of the two oils interacts.
• CIncorrect. Spectrometric oil analysis measures wear metals by their emission spectra, not by the color of the oil.
• DIncorrect. Synthetic turbine oils are identified by specification and approved brand, not by SAE grade. A grade mismatch is not the reason for the restriction.

Answer: C) Moisture buildup

• AIncorrect. This is not a result.
• BIncorrect. Cool oil is thicker.
• CCorrect. Water and acids are not boiled off, leading to sludge and corrosion.
• DIncorrect. This is not a result.

Answer: A) Oil inlet to the engine

• ACorrect. That reflects oil going to the bearings.
• BIncorrect. That isn't the location.
• CIncorrect. That isn't the location.
• DIncorrect. That isn't the location.