FAA Powerplant Written Practice Test

What is a characteristic of Dyna-focal engine mounts in aircraft reciprocating engines?

1. Shock mounts point towards the engines' center of gravity

2. Shock mounts are fixed and non-adjustable

3. They are made from lightweight composite materials

4. Mounts are designed to absorb all vibrations completely

The correct answer is: Shock mounts point towards the engines' center of gravity

Dyna-focal engine mounts are specially designed to enhance the stability and performance of aircraft reciprocating engines. A key characteristic of these mounts is that the shock mounts point towards the engine's center of gravity. This design feature allows for better alignment and distribution of forces during operation, which minimizes vibration transmitted to the airframe. By directing the shock mounts towards the center of gravity, the Dyna-focal system takes advantage of the natural balancing forces within the engine. This setup effectively helps maintain the engine's position, reduces stress on the mount components, and contributes to improved handling and overall aircraft performance. In contrast, the other characteristics listed do not accurately represent Dyna-focal mounts. For example, shock mounts are not fixed and non-adjustable as that would limit the flexibility necessary for adjusting alignment during maintenance. Additionally, while materials used in engine mounts can vary, it is not exclusive to lightweight composite materials. Lastly, while these mounts do absorb vibrations, they are not designed to completely eliminate them, as some level of vibration is inherent in engine operation.