WASHINGTON — The Advanced Turbine Engine Company has lodged a legal protest of the U.S. Army’s decision to award a contract for its next-generation helicopter engine to rival General Electric Aviation, the company disclosed Tuesday.

Earlier this month, GE Aviation beat ATEC — a Honeywell and Pratt & Whitney joint venture — to win the $517 million award for the engineering, manufacturing and development phase of the Improved Turbine Engine Program, or ITEP.

"In our review of the evaluation, we clearly offered the best value through a combination of a highly rated and technically superior engine that was judged to be much lower risk, and believe we did so significantly under the government's budget,” ATEC President Craig Madden said. “We are requesting that the government review these facts and award the ITEP contract to ATEC, the best engine and the one that our warfighters and taxpayers deserve."

The protest was filed through the Government Accountability Office on Feb. 19. The GAO has three months to make a decision on whether to reopen the competition.

GE Aviation stated that it was aware of ATEC’s protest and was confident the Army’s contract award would not be overturned.

“Our position is that the Army Contracting Command conducted a comprehensive and well-organized process with clearly defined requirements and a level playing field for both competitors. We will support the Army and Government Accountability Office throughout this process,” it said in a statement.

“We put forward a very compelling proposal with the T901, which meets or exceeds all Army requirements for the ITEP program. We are very confident the Army’s very thorough review and evaluation of the competing bids will be upheld and that the T901 will prevail.”

The stakes for both ATEC and GE Aviation are huge.

Both companies have spent about a decade and billions of dollars to develop technology for their ITEP designs, and the winner of the competition will supply new propulsion systems for the AH-64 Apache attack helicopter, UH-60 Black Hawk utility helicopter and possibly the Army’s Future Attack Reconnaissance Aircraft.

ATEC proposed the T900, a dual-spool engine that executives said gave it more growth potential and greater fuel efficiency.

GE, which produces the T700 engine that currently powers the Black Hawk and Apache, offered a single-spool engine called the T901. Company officials said that having a single spool would cut down weight and cost, and make it easier to maintain.

Updated Feb. 20, 2019 at 9:41 a.m. EST with a statement from GE Aviation.