FAA Powerplant Written Practice Test

What step is necessary prior to checking the oil level on a dry sump engine?

1. Ensure the engine is cold

2. Turn the propeller several times to pump oil to the tank

3. Remove the oil filler cap

4. Check the oil level after starting the engine

The correct answer is: Turn the propeller several times to pump oil to the tank

Before checking the oil level on a dry sump engine, it is essential to turn the propeller several times to pump oil to the tank. In a dry sump engine, oil is stored in a separate tank rather than in the crankcase. This means that oil needs to be circulated by the engine's oil pump. By turning the propeller, you activate the engine's oil pump, which allows the oil to flow through the system, ensuring that any oil that should be returned to the tank is circulating correctly. This action provides an accurate reading of the oil level in the tank, as any trapped oil that may not return to the reservoir during the previous operation will now be accounted for. Checking the oil level after starting the engine would not yield a precise measurement, as the oil typically expands when heated, affecting the accuracy of the reading. Ensuring the engine is cold is generally good practice, but the primary requirement before checking the oil level is ensuring that oil is pumped back into the tank to obtain an accurate measurement. Removing the oil filler cap does not independently ensure accurate oil level measurement; it is simply a necessary part of accessing the tank for inspection. Proper sequencing of these steps is crucial for accurate maintenance checks.