FAA Aviation Mechanic Powerplant (AMP)Fuel, Induction and LubricationEasy
A technician is inspecting the oil system of a reciprocating engine that uses a wet-sump lubrication system. Which of the following is a characteristic of a wet-sump system?
- AIt is typically used on large radial engines for cooling efficiency.
- BIt requires multiple scavenge pumps to return oil to a reservoir.
- CIt utilizes an external oil tank separate from the engine crankcase.
- DThe oil supply is contained within the engine crankcase.
Show answer & explanationAnswer & explanation
Correct answer: D. The oil supply is contained within the engine crankcase.
In a wet-sump lubrication system, the oil supply is stored directly in the bottom of the engine crankcase, which acts as the oil reservoir. This simplifies the system by eliminating the need for an external tank and scavenge pumps.
Why the other options are wrong
- A. While some large radial engines might use wet sumps, dry sumps are more common for larger, higher-performance engines due to better cooling and capacity, making this a less accurate primary characteristic.
- B. Multiple scavenge pumps are characteristic of a dry-sump system to return oil from various points to an external tank.
- C. This describes a dry-sump system, not a wet-sump system.
Wet-Sump Lubrication System
A lubrication system where the engine oil supply is stored directly in the crankcase, which also serves as the oil reservoir.
- Simpler design, fewer components.
- Common in smaller, lower-power reciprocating engines.
- Oil capacity limited by crankcase size.
Memory trick: Wet means 'within' the engine, dry means 'distant' tank.