UPDATE 1-AMR expects drop in mainline unit revenue

* Cargo revenue also down

* AMR expects to report cash, investments of $3.3 bln

* Special items for quarter expected to total $70 mln

(Adds costs, special items)

WASHINGTON, June 18 (Reuters) - AMR Corp (AMR.N), the parent of American Airlines, expects to report a 16 to 17 percent year-over-year decrease in mainline unit revenue for the quarter, the company said on Thursday.

American also said in a regulatory filing that second quarter cargo and other revenue is anticipated to decline between 7.8 and 8.8 percent.

The company forecasts cash and short-term investments of $3.3 billion for the period.

The carrier forecasts mainline unit costs, excluding fuel and other items, of 8.5 cents for the April through June period.

American anticipates about $70 million in special items for the quarter.