What does the 14 CFR Part 43 Appendix D require during an annual/100-hour inspection of a reciprocating engine?

The requirement for a cylinder compression check during an annual or 100-hour inspection of a reciprocating engine is indicated by 14 CFR Part 43 Appendix D, which sets forth the criteria for these inspections. This inspection is critical as it directly assesses the engine's health and efficiency. A cylinder compression check involves measuring the pressure within each cylinder during the engine’s compression stroke, which helps identify any issues related to the piston rings, valves, or cylinder walls. Efficient sealing within the cylinders is crucial to maintaining power output and fuel efficiency, and a compression check can reveal leaks or mechanical failures that may lead to diminished engine performance.

In addition, a compression check allows for early detection of wear and potential failures, allowing for timely maintenance decisions and reducing the risk of in-flight issues. This thoroughness ensures that the engine continues to operate safely and effectively, aligning with the regulatory requirements meant to uphold aviation safety standards.