FAA Powerplant Written Practice Test

What describes full-floating piston pins?

1. They connect directly to the crankshaft

2. They allow motion between the pin and the small end of the connecting rod

3. They are fixed in place to prevent movement

4. They are designed for quick disassembly

The correct answer is: They allow motion between the pin and the small end of the connecting rod

Full-floating piston pins, also known as wrist pins, are designed to allow motion between the pin and the small end of the connecting rod. This design facilitates the loading and unloading of the connecting rod during the piston’s stroke and allows for a more refined movement of the piston within the cylinder. The ability of the piston pin to float freely in the small end of the connecting rod helps to minimize wear and stress on the components, allowing for better performance and longevity of the engine. This characteristic is particularly important in high-performance engines where precise movement is essential for efficiency and reliability. The other descriptions do not accurately convey the function of full-floating piston pins. For instance, they do not connect directly to the crankshaft; rather, they allow the connection of the piston to the connecting rod while still providing for necessary movement. They are not fixed in place; fixing them would inhibit the desired motion critical for engine function. Additionally, their design does not primarily focus on quick disassembly; the floating characteristic is more significant in performance criteria than in assembly convenience.