When an MD-80 jet plunged into the Pacific Ocean Jan. 31, killing all 88 aboard, Alaska Airlines' image as one of the safest airlines in the USA began to take a beating. A further blow could be delivered today when the Federal Aviation Administration announces whether it is satisfied with Alaska's response to an audit that showed troubling problems in the company's heavy maintenance facility. In the audit, the FAA said inspectors found two Alaska jets had been improperly returned to service even though the airline hadn't properly certified that all maintenance had been completed. The inspectors threatened to shut down the maintenance facility - a move that one Alaska official says could cripple the carrier.