In article .com,
says...
Anyone else here ever experience one? How did yours happen?

Didn't happen to me, saw the airplane in a hangar next to the one I
was working in and asked.

Seems the not very old Cessna 172 was towed out of the hangar by a
friend of owner. This friend had permission to fly it and was an
instructor. The instructor/friend towed the airplane out using a golf
cart they have for the purpose. After pulling the airplane out and
turning it away from the hangar door and aligning it with the taxiway,
the guy disconnnects the golf cart and puts it into the hangar and
closes the hangar door. Then he comes back out and climbs into the
airplane and fires it up.

Nothing happened right away, not at idle anyway. The prop missed the
still attached towbar. But when the engine was revved up for the
runnup, the lowered pressure in front of the prop sucked the tow bar
up and I guess caused a sudden stop.

When I saw the airplane it was without it's engine and prop. The prop
had to be replaced and the engine overhauled. The prop was a constant
speed version. Pretty costly whoops.

Corky Scott