How Old is Too Old?

In just the last few years, a series of T-34s, the military equivalent of a Bonanza, have suffered wing separations. An emergency airworthiness directive (AD) grounded the fleet. Just a couple of months ago, a well-maintained T-6, a World War II trainer, lost a wing doing maneuvers over Florida. With the general-aviation aircraft now averaging just less than 30 years of age, how can you tell if an airplane is safe to fly?