What is a potential issue with using flat grain in aircraft wood?

Using flat grain in aircraft wood can potentially lead to structural weakness due to the orientation of the wood fibers. In flat-grain timber, the growth rings are oriented nearly parallel to the flat surface of the board, which can result in less strength compared to vertical grain wood, where the fibers are aligned more vertically. This alignment provides greater load-bearing capacity and resilience, which are critical in aviation applications where the integrity and strength of materials are paramount for safety and performance.

The structural characteristics of wood, including its grain orientation, play a vital role in how it behaves under various stresses. Flat grain may not handle the forces experienced during flight as effectively as vertical grain wood, leading to a higher risk of failure in critical components that rely on the wood for strength. Therefore, selecting the appropriate grain orientation is essential for ensuring the durability and reliability of aircraft structures.