What is a common defect in flat grain boards that may affect their performance?

Flat grain boards are oriented such that the annual growth rings are primarily parallel to the surface of the board, which can lead to a common defect: they warp easily. This warping is largely attributed to the inherent structure and moisture content in the wood. When the wood dries or absorbs moisture unevenly, the different growth patterns can cause stresses that lead to warping. This defect can significantly impact the performance of flat grain boards in aviation applications, as stability and structural integrity are critical for safety and functionality.

While other options present characteristics related to wood, they do not specifically address the unique issues associated with flat grain boards as effectively as warping does. Flexibility, density, and splintering may be concerns for different types of wood or grain orientation, but warping is particularly relevant to flat grain boards' performance and usability in various applications. Understanding these wood defects is crucial for ensuring the correct materials are selected for aviation purposes.