FAA Powerplant Written Practice Test

During an overhaul, how are reciprocating engine exhaust valves checked for stretch?

1. By visual inspection

2. Using a manufacturer's contour gauge

3. By measuring the spring force

4. By checking the valve surface for cracks

The correct answer is: Using a manufacturer's contour gauge

During an overhaul, the correct method for checking reciprocating engine exhaust valves for stretch is by using a manufacturer's contour gauge. This tool allows for precise measurement of the valve’s profile against a known standard, helping to determine if the valve has become elongated or altered shape due to heat and stress over time. Using a contour gauge is crucial because it provides a reliable way to assess whether the valve has maintained its design specifications. If a valve has stretched, it may not close properly, leading to potential engine inefficiency or damage. This method is an industry-standard practice for maintaining the integrity of engine components and ensuring optimal performance. Visual inspection alone does not provide the necessary precision, as visual cues may not reveal subtle distortions in the valve. Measuring spring force, while important for evaluating valve function, does not address the dimensional integrity of the valve itself. Checking the surface for cracks is essential for overall valve condition, but it does not specifically assess stretch. Thus, utilizing a manufacturer's contour gauge is the most effective method for this specific inspection.