"Engines are sometimes leased separately and shuffled around within an airline’s fleet . . ."
"Cut-rate Tower Air kept its wide-body fleet flying by quietly dismantling a trio of 747s leased from GMAC and dispersing the components among its 18 other airplanes."
"We just watched and waited until the crew checked into their hotel", Popovich says, "then we grabbed their plane and flew away."
That certainly doesn't sound like they're doing a lot of inspection to ensure a safe return. Granted, it's only their hind-ends and they are aware of the risks, but I think this guy and his crew certainly deserve a brass balls award.
If my experiences with my own (single piston engined) airplane are in any way representative, I would be surprised if the first flight out of major maintenance isn't statistically significantly riskier than a random repo flight.