In which locations are splices to a wood spar prohibited?

Splices in wood spars are prohibited under load-bearing components, such as where an engine mount is attached. This is because the load-bearing zones of a spar must maintain maximum structural integrity to ensure they can safely support the weight and forces applied during operation. The integrity of the wood spar in these high-stress areas is critical to prevent potential failure, which could result in catastrophic consequences.

When splices are introduced in these vital areas, they can create weak points and may not be able to withstand the forces from the engine mount effectively. Therefore, it's essential to maintain continuous, unbroken spar materials in these load-bearing locations, ensuring the aircraft's structural strength remains uncompromised.

Splices may be acceptable in other areas of the wing, like the tip or center, but special consideration must be given to how those sections are loaded during flight. Non-structural areas typically do not bear significant loads, allowing more flexibility for splicing without risking structural failure.