Less than four full years into operation, the KFC Yum! Center has accounted for an estimated economic impact of more than half a billion dollars since it opened.So says an outside consulting firm that added up the dollars from arena ticket, concession and merchandise sales, along with estimated spending on hotel rooms, restaurants, bars, shopping, transportation and other entertainment. “This is a real economic engine,” said John Kaatz, a principal in the Minneapolis office of CSL International. CSL presented its findings at a Wednesday lunch event of the Louisville Conventions & Visitors Bureau, which commissioned the study. The big takeaways: -An estimated 839,000 people will have attended KFC Yum! Center events in the current fiscal year that ends June 30. While that represents a 3.3 percent increase over its first full year of operation in 2011-12, it is essentially even with 2012-13. -Visitors spent an estimated $47.8 million on tickets, concessions and merchandise at the arena, up 12.2 percent from 2012-13. -Visitors spent an estimated $32.3 million outside the arena, mostly on food, drinks and hotels, up 58 percent from 2012-13. -While the arena has generated an estimated $346 million in direct spending since it opened, indirect spending boosts the figure to $581 million. -Tax collections have totaled $29.1 million, mostly in state sales taxes. Louisville Mayor Greg Fischer said the arena is just one facet of what it takes to be one of the “great cities.” “KFC Yum! Center generates a buzz that people like to be around,” he said. The arena still doesn’t pay for itself. Because of bond debt that stood at $353.2 million at the end of 2013, it finished the year with a net deficit of $11 million, down from $16.9 million in 2012. But Louisville Council President Jim King said the reports shows that KFC Yum! Center has given the city a “powerful return” on its investment. “While the last four years have been a challenge to say the least, if I had to do it all over again, I’d do it,” he said. “We’ve had a lot of people question our judgment and sanity, but this validates our thought process.”