Navistar may close plants to cut costs, CEO says LISLE, Illinois (Reuters) - Embattled U.S. truck and engine maker Navistar International Corp (NAV.N) is cutting administrative and engineering spending and may close factories as it works to lower its costs, the company's newly named chief executive said on Thursday. The company is cutting its white-collar work force by about 800 people through a combination of voluntary buyouts and layoffs, reducing its engineering spending by 28 percent and will next review whether it needs all 19 of its North American factories, CEO Lewis Campbell said in his first interview since taking the reins at Navistar on August 27. We are now looking at what are the range of industry volumes that could come to us over time and what is the right footprint? More than likely we'll have to adjust our footprint. And we're ready to do that," said Campbell. The Lisle, Illinois-based company is also reviewing whether to close or sell any of its businesses outside of its core North American truck and engine operations, Campbell said. Reporting by Scott Malone; Editing by Leslie Gevirtz