FAA Powerplant Written Practice Test

What happens if a full-flow oil filter on an aircraft engine becomes completely clogged?

1. The oil pump will stop

2. The bypass valve will open

3. The filter will explode

4. The engine will shut down

The correct answer is: The bypass valve will open

When a full-flow oil filter becomes completely clogged, the design of the oil filtration system includes a bypass valve that automatically engages to maintain oil flow to the engine. This bypass mechanism allows oil to bypass the filter element and continue circulating, ensuring the engine remains lubricated even with a blocked filter. The bypass valve is a crucial safety feature in aircraft engines, preventing complete oil starvation that could lead to engine failure. It is designed to open when the pressure difference across the filter exceeds a certain threshold, typically indicating that the filter is obstructed. Therefore, selecting the option pertaining to the bypass valve opening directly correlates with the function and intent of an oil filtration system in aviation engines, which prioritizes the consistent flow of oil over absolute filtration in emergency situations.