What is mandated by 14 CFR Part 43 Appendix D for an annual/100-hour inspection on engines?

The requirement for a cylinder compression check during an annual or 100-hour inspection on engines is significant because it helps ensure the overall health and performance of the engine. A cylinder compression check measures the pressure within each cylinder during the compression stroke, providing key insights into the engine's internal condition.

Low compression can indicate issues such as worn piston rings, leaking valves, or head gasket failures, which can severely affect engine performance and reliability. Conducting this test allows mechanics to identify problems early, which can prevent more severe damage and costly repairs down the line.

Additionally, while other checks like magneto timing, fuel system integrity, and valve clearance monitoring are important for overall engine maintenance, the cylinder compression check is explicitly mandated as part of the guidelines for comprehensive inspections. Therefore, this test is vital in evaluating the engine's ability to maintain proper power output and operational efficiency, making it an essential part of the inspection process required by regulatory standards.