The C 152 which I solo'd first in 1977 had at the time 33 hour TTSN (my instructor was yelled at for sending me first solo in a brand new, ferry time only plane). It was sold to a private owner more than 10 years ago with 14,000+ hours.
I used to fly a C 207 with 19,800 hours on it. It was a bit tired, but entirely airworthy. One crack in a doorpost doubler for which I approved a recurring inspection, never another problem with it.
On the other hand, my 1977 Teal has 462 hours TTSN, of which I've flown 140! (It sat a long time!)
When I last did Twin Otter fleet research for Bombardier in 1999, the high time Twin Otter had 50,302 hours, and the high cycle Twin Otter had 109,579 airframe cycles, though with 42,292 hours. Those aircraft would have been through major rebuilds to get to those high times.