FAA Powerplant Written Practice Test

What characteristic does the crankpin have to reduce its weight?

1. It is made of aluminum

2. It is hollowed out

3. It is coated with titanium

4. It has additional counterweights

The correct answer is: It is hollowed out

The crankpin is designed to reduce its weight primarily through the use of hollowed-out construction. This technique allows for a substantial reduction in mass while maintaining structural integrity and strength. By creating a hollow section, engineers can eliminate excess material that would otherwise contribute to the weight of the crankpin without compromising the ability to withstand the operational stresses it encounters. Using specific materials like aluminum would indeed reduce weight, but that is not the fundamental characteristic of the crankpin itself. Coating it with titanium would not address the overall weight-specific design of the crankpin but rather add a layer for wear resistance or corrosion protection. Additionally, while counterweights can help in balancing and managing vibrations, they do not contribute to reducing the weight of the crankpin itself directly. Thus, the hollow design is the most effective approach taken in crankpin construction to achieve weight reduction.