UPDATE 1-Pentagon plans to halve cargo aircraft program

(Adds details, congressional reaction, background)

WASHINGTON May 7 (Reuters) - The U.S. Department of Defense will ask Congress to cut in half a $2 billion joint Air Force-Army plan to acquire L-3 Communications Holdings Inc (LLL.N) cargo planes, a Pentagon document obtained by Reuters shows.

Instead of as many as 78 C-27J Spartan aircraft, the department will seek to buy 38 -- 13 currently on order plus 25 in fiscal 2010 to 2012, according to the document titled "Resource Management Decision No. 802."

In addition, the Army would transfer the program, known as the Joint Cargo Aircraft, and the direct support airlift mission it involves to the Air Force, the decision memorandum says.

In a May 1-dated letter to Defense Secretary Robert Gates, 13 members of the House of Representatives voiced opposition to earlier reports of the plan.

"We believe that, if implemented, such cuts would impede the ability of the United States Army, specifically the Army National Guard, to meet intra-theater lift requirements ... as well as severely constrain the Army and Air National Guard's ability to respond to a domestic disaster," the lawmakers wrote.

The aircraft is designed to meet the tactical needs of ground commanders, sometimes referred to as transporting cargo the "last tactical mile," as well as for homeland security emergency missions, including ferrying hurricane supplies.

Lance Martin, a spokesman for L-3, the program's prime contractor, did not immediately return a phone call seeking a comment. The airframe is being supplied by Alenia North America Inc, a unit of Italy's Finmeccanica SpA (SIFI.MI), under a Pentagon contract awarded in 2007.

The program reduction is expected to be announced later Thursday as part of President Barack Obama's detailed spending plan for fiscal 2010, which starts Oct. 1.

It would add to the list of arms programs targeted for cuts by Gates, who is seeking to shift more resources to deal with wars such as those in Afghanistan and Iraq. (Reporting by Jim Wolf, Editing by Maureen Bavdek)