There is an old story that goes like this:
Two airplanes are, late one night, sitting in a hangar, one made of wood and the other of metal. The metal airplane, feeling very superior and modern, looks sideways at the wooden airplane and whispers, "Dry rot". The wooden airplane, knowing the true score, whispers back, "Metal fatigue".
The point being that a wooden structure, properly protected from moisture, has a virtually unlimited life, being free from fatigue issues. Many restorations of antique aircraft have reused spars that in some cases are over 60 years old. Metal fatigue can be mitigated with good design (DC-3, anyone?), but will always be an issue. Wood needs more particular and specialized care, which is a big selling point for metal structure.
Many purpose-built aerobatic monoplanes and biplanes use wood for their wing structure, where it's high strength and light weight are useful.
|