The Federal Aviation Administration may face a partial shutdown on Friday. Nineteen stop-gap funding extensions already have been required, but a twentieth has yet to be agreed on. House Republicans and Senate Democrats are accusing each other of refusing to negotiate about the FAA. Industry spokesmen say funding delays are jeopardizing airport expansion and modernization, and threatening jobs and economic activity. Ben Mutzabaugh, travel reporter for USA Today, says the FAA might have to furlough 4000 workers if there's no agreement tomorrow.