NY -- Standard&Poor's CreditWire 7/31/96 -- Standard&Poor's today has affirmed its ratings of AMR Corp. and unit American Airlines Inc. (see table below). The rating outlook has been revised to positive from stable. About $6.7 billion of securities is affected. The outlook revision reflects ongoing progress in restoring financial strength and the potential revenue and competitive advantages of a proposed alliance between American Airlines and British Airways PLC. AMR's rising earnings and a sharp reduction in capital expenditures since the early 1990s have generated free cash flow for debt repayment, cutting debt and off- balance sheet leases from a peak of about $17 billion to less than $14 billion now. Further progress is anticipated from continued