FAA Powerplant Written Practice Test

Which two components are standard in most light sport aircraft two-stroke engines?

1. Electric cooling fans and turbochargers

2. Breaker magnetos and rotary valves

3. Gravity feed fuel system and oil injection system

4. Dual spark plugs and electronic fuel injection

The correct answer is: Gravity feed fuel system and oil injection system

In light sport aircraft that utilize two-stroke engines, a gravity feed fuel system and an oil injection system are commonly standard components. The gravity feed fuel system allows fuel to flow directly from the tank to the carburetor under the influence of gravity, ensuring a simple and lightweight design that minimizes potential mechanical failures often associated with fuel pumps. This system is particularly advantageous in small aircraft, where reliability is paramount. An oil injection system is vital in a two-stroke engine because it provides a consistent and controlled way to mix oil with fuel. Two-stroke engines require the mixing of oil and fuel to lubricate the engine components effectively. An oil injection system automates this process, ensuring the engine receives the proper amount of oil for optimal performance while maintaining efficiency and reducing emissions compared to pre-mixing fuel and oil manually. The focus on lightweight, uncomplicated solutions in light sport aircraft makes these two systems particularly fitting for the design and operational requirements of such aircraft. In contrast, other choices suggest components not typically associated with the standard configurations of light sport aircraft two-stroke engines.