Portland-based SeaPort Airline is facing a proposed $500,000 civil penalty from the Federal Aviation Administration over maintenance issues with three of its single-engine Cessna Caravan aircraft. The airline, which filed for Chapter 11 bankruptcy in February, is cooperating with regulators and in fact reported the problem to the government in the first place, said President Tim Sieber. The government alleges SeaPort failed to do specific inspections on the planes' turbine compressor blades over...