On July 18, 2012, about 2200 central daylight time, a Bombardier CL-600-2C10 airplane, N502AE, operating as American Eagle Flight 3773, diverted to the General Downing-Peoria International Airport (KPIA), Peoria, Illinois, due to weather. During the approach the crew detected smoke and after landing, an emergency evacuation was performed. The two pilots, two cabin crew, and 52 passengers were uninjured. One passenger sustained a serious injury during the egress. The airplane was owned and operated by American Airlines, Inc. under the provisions of the Code of Federal Regulations Part 121 as a scheduled passenger flight. Night visual meteorological conditions prevailed for the flight that was operated on an instrument flight rules flight plan. The flight departed Denver International Airport (KDEN) about 1855 mountain daylight time, and was originally destined for the Chicago O'Hare International Airport (KORD), Chicago, Illinois. The flight had diverted from KORD to KPIA due to weather. While on a three mile final to land, the crew detected smoke in the airplane. After landing, the crew directed an emergency ground egress. The two over wing exit and the main entrance door was utilized for the evacuation. During the egress, one passenger sustained a broken ankle. No obvious source of the smoke was determined during a post-landing examination. No damage to the airplane was observed. An examination of the airplane revealed that the airplane was operating on a single environmental pack, allowed per the airplane's minimum equipment list. The remaining environmental pack failed while the airplane was on final approach, reverting the system to allow ambient air to enter the airplane. There were no sources of fire located within the airplane. However, along the airplane's approach path to the airport, it overflew a large house fire.