A series of aircraft incidents — from a tire falling off to an engine fire — prompted the Federal Aviation Administration to place United Airlines under “increased oversight.” The airline confirmed that to employees in a March 22 letter from Sasha Johnson, United Airlines corporate safety vice president. “The number of safety-related events in recent weeks have rightfully caused us to pause and evaluate whether there is anything we can and should do differently,” she wrote. ‘We’ve stepped up our interactions with the FAA recently and they echoed these sentiments.” FAA officials confirmed that …