FAA Powerplant Written Practice Test

When overhauling a certified aircraft reciprocating engine, how can steel valve seats be finished?

1. Only by grinding them down

2. By any method available

3. Wet or dry sanding

4. Using only cutting tools

The correct answer is: Wet or dry sanding

Finishing steel valve seats during the overhaul of a certified aircraft reciprocating engine must be done with care to ensure a proper fit and seal for the engine's operation. The correct choice highlights that both wet and dry sanding can be utilized as methods to achieve this finish. Wet sanding involves the use of a lubricant, which can help to reduce the risk of overheating the metal and provides a smoother surface finish by minimizing scratches and imperfections. Dry sanding is equally effective and can be used for quick adjustments or when the area is more accessible. The emphasis on these techniques acknowledges the importance of achieving a precise surface finish that allows for optimal performance and longevity of the valve seats in the engine. Other options suggest restrictions that do not apply as broadly; for example, stating that only grinding or cutting tools are permissible does not encompass the full range of acceptable finishing methods approved for use in aviation maintenance practices.