It had just come out of overhaul and something in the hub broke. There was an AD issued as a result. I was flying a MU-2B-60 Marquise and when we got on the ramp, I could take my hand and rotate each blade lock to lock. Unbelievably, there was no engine damage, but the airframe couldn't care less why the engine is not producing thrust.
I also left one off of the SE piston failures...
Back in 1976, I had the opportunity to go pick up a brand spanking new C182 at the Cessna delivery center in Wichita. On climb out, out of 5,000 feet, the engine started to run extremely rough. I declared an emergency and returned the d@mn thing back to Cessna. They had it for another day before I was able to leave.
Which brings up the point, most (80%?) of my inflight issues have occurred with new airplanes or new engines or recent major maintenance performed by factory service centers. The 737-40 precautionary shutdown was on a brand new airplane that had only been on the property one week.
My aviation mentor one told me that the most dangerous flying you'll ever do is in brand-new equipment or just out of major maintenance. I have come to know that he was bang on.
NEVER let your guard down. Fly safely, my friends.