By Nathalie Tadena AAR Corp. (AIR) said it expects to post record fiscal fourth-quarter revenue above Wall Street's estimates, but forecast earnings for the latest period and its new fiscal year below analyst expectations. The company also authorized $50 million in share buybacks, a move that comes as the the aircraft leasing and maintenance company looks to increase shareholder value. For the quarter ended May 31, AAR projected revenue between $560 million to $565 million, marking the highest quarterly sales in the company's history. Analysts polled by Thomson Reuters had projected $549 million. The company said sales to commercial customers are anticipated to increase by about 40%, while government and defense sales are expected to decline year-over-year. Meanwhile, AAR projected adjusted earnings for the fourth quarter between 44 cents and 46 cents a share, below the 48-cent estimate from analysts. For fiscal 2013, AAR expects sales between $2.1 billion and $2.2 billion, while analysts had projected $2.22 billion. AAR sees earnings of $1.55 to $1.65 a share, below the $2.15 estimate from analysts. AAR said it expects commercial aviation results to increase year-over-year in 2013, helped by recently acquired Telair International GmbH and Nordisk Aviation Products AS, while its airlift business will benefit from efforts to improve aircraft availability. However, AAR expects results for its mobility products and defense systems logistics businesses to decline on the year. AAR's top line has grown in recent quarters, though at a somewhat slower pace, as a rebounding commercial-airline sector has driven demand for parts and maintenance services. The company on Dec. 2 completed its purchase of Telair--which manages aircraft cargo-loading systems for Boeing Co. (BA) and Airbus--and Nordisk Aviation, which designs and manufactures heavy-duty pallets and lightweight cargo containers for commercial airlines. In March, AAR reported its fiscal third-quarter earnings rose 15% as the aircraft leasing and maintenance company posted higher sales in its structures and systems segment thanks to acquisitions. The company will release its results on July 17. Shares were off 4.7% to $11.03 after hours. Through the close, the stock has fallen 47% over the past three months. -Write to Nathalie Tadena at nathalie.tadena@dowjones.com