FAA Powerplant Written Practice Test

What is the purpose of a last chance oil filter?

1. To enhance oil viscosity

2. To prevent clogging of the oil spray nozzles that spray the main bearings

3. To catch contaminants before entering the fuel system

4. To assist in oil cooling

The correct answer is: To prevent clogging of the oil spray nozzles that spray the main bearings

The purpose of a last chance oil filter is specifically to prevent clogging of the oil spray nozzles that deliver oil to the main bearings. In aircraft engines, maintaining proper lubrication is crucial for the performance and longevity of engine components. The oil spray nozzles play a vital role in directing oil to the main bearings, which are critical for supporting the rotating components and reducing friction. If contaminants or debris present in the oil were to clog these nozzles, it could lead to inadequate lubrication of the bearings. This could result in increased wear, overheating, and ultimately, catastrophic engine failure. Therefore, the last chance oil filter is strategically placed to capture any contaminants that might bypass earlier filtration systems, ensuring that only clean oil reaches the nozzles and properly lubricates the bearings. The other options, while related to oil and engine operations, do not accurately describe the specific role of a last chance oil filter. Enhancing oil viscosity or assisting in oil cooling are properties of the oil itself or separate systems and do not directly relate to the filter's function. Similarly, catching contaminants before entering the fuel system pertains more to fuel filters, which serve a different purpose in maintaining the integrity of the fuel supply system.