* U.S. Air Force vows to continue work on program
* Sierra Nevada, Embraer building 20 planes for Afghanistan
WASHINGTON, March 21 (Reuters) - Beechcraft Corp said on Thursday it was suing the U.S. Air Force to halt work on a contested aircraft contract won by Brazilian planemaker Embraer and its U.S. partner while federal auditors review Beechcraft's protest against the contract.
The Air Force last week authorized U.S.-based Sierra Nevada Corp and Embraer to resume work on a $428 million order for 20 light attack planes for Afghanistan, overriding a stop-work order issued after a protest filed by Beechcraft with the Government Accountability Office.
On Thursday, Beechcraft challenged the Air Force's decision to allow continued work on the program by filing a lawsuit with the U.S. Court of Federal Claims.
The Air Force said it was aware of Beechcraft's lawsuit, but remained confident about the way the competition was handled, and planned to continue work on the program.
"Nevada-based Sierra Nevada Corporation will continue work on the (Light Air Support) contract pending any further direction from the court," said spokesman Ed Gulick.
"The override to the stay of performance was issued to honor a critical and time-sensitive U.S. commitment to provide air support capability to the Afghanistan Air Force," he said.
Thursday's court filing by Beechcraft is the latest twist in an ongoing battle over the Afghan plane orders - a dispute that has drawn the ire of the Brazilian government and which could complicate U.S. plans to withdraw from Afghanistan in 2014.
Privately-held Sierra Nevada said it and Embraer were moving forward on the contract.
"We fully understand the urgency of this mission and intend to provide a superior product right on schedule," Sierra Nevada said in a statement, adding that the contract would support 1,400 jobs across the United States.
Embraer last week signed a 10-year lease on a 40,000-square-foot facility in Jacksonville, Florida, where it plans to assemble the 20 A-29 Super Tucanos for delivery to Afghanistan.
Sierra Nevada said the signing of the lease was "an important step toward fulfilling the LAS contract and further developing the U.S. aviation industrial base."
Brazilian officials expressed dismay last year when an original December 2011 award to Sierra Nevada and Embraer was withdrawn.
The Air Force is racing to get new planes to Afghanistan and train pilots to fly them as U.S. forces prepare to withdraw from the country after over a decade of war.
Beechcraft emerged from Chapter 11 bankruptcy protection last month. The aircraft maker has called the Air Force's latest move to continue work on the contract "misguided."