What does a straight lay line on a flexible hose indicate?

A straight lay line on a flexible hose indicates that the hose is properly installed. This line serves as a visual reference to ensure that the hose is positioned correctly without any twists or kinks during installation. If the lay line is straight and aligned with the expected routing path, it confirms that the hose has been installed in a manner that allows for optimal flow and prevents any stress that could lead to potential failure or wear over time.

In contrast, if the lay line were not straight, it could suggest improper installation or that the hose has twists or bends, potentially leading to issues such as reduced flow, increased wear, or even a risk of damage. Therefore, the straight lay line is a critical indicator in assessing the installation quality of flexible hoses in aviation applications.