FAA Powerplant Written Practice Test

What material is commonly found in turbofan engine inlets to reduce noise?

1. Sound absorbing foams

2. Sound reducing materials

3. Reinforced plastics

4. Composite materials

The correct answer is: Sound reducing materials

The correct answer is sound reducing materials. In the design of turbofan engine inlets, various advanced materials that are specifically engineered to dampen sound frequencies emitted by the engine are often utilized. These materials can include specialized foams or composites that are effective in absorbing sound waves, which helps to mitigate the noise produced during engine operation. The primary goal is to minimize the noise footprint of the aircraft, particularly during takeoff and landing when noise levels are most critical for compliance with regulations and community acceptance. While sound absorbing foams may also play a role, the term "sound reducing materials" encompasses a broader range of options, including various engineered composites and other techniques designed for effective noise reduction. Reinforced plastics and composite materials could also contribute to structural integrity and weight reduction but are not primarily focused on sound attenuation, which distinguishes the correct answer from the other options.