The airline will be credited $25 million for its improvements in wheelchair handling and payments made to affected passengers. The U.S. government fined American Airlines $50 million for failing to provide wheelchair assistance to passengers with disabilities and damaging thousands of wheelchairs over a five-year period.The Transportation Department said Wednesday that “in some cases,” wheelchair users were injured, but it did not give a number.American said it has made significant investments to improve the handling of wheelchairs.