Stringent speed requirements originally set out by the US Air Force for its UH-1N Huey replacement would have pushed Bell Helicopter’s UH-1Y Venom out of the competition.

In February, the service announced it would delay the release of its final request for proposal to recapitalise its Huey fleet, after contractors told the service their off-the-shelf solutions would not meet all of the proposed requirements.

The competition has piqued the interest of at least four contenders including Sikorsky with its UH-60M Black Hawk, Airbus Helicopters offering the UH-72A Lakota, Leonardo Helicopters pitching the AgustaWestland AW139 and Bell proposing its UH-1Y.

The USAF is discussing the requirements with industry and plans to release a second RFP this month, with the final requirements scheduled to be unveiled this summer, the service says.

For Bell, the air force’s specific requirements for speed, endurance and payload affected its bid, Scott Clifton, director of global military business development at the aiframer, tells FlightGlobal. The UH-1Y fell short of the air force’s proposed speed requirement by 3-7kt (5.5-13km/h), Clifton says.

Bell would have needed to modify the helicopter to meet those speed requirements, which would have delayed the timeline to field the aircraft. The GE Aviation T700-401C powers the UH-1Y today, but the Venom could reach higher speeds by upgrading to the -701D engine found in the Black Hawk and Boeing AH-64E Apache.

“When [USAF] said ‘it needs to go this fast,’ the speed was slightly different,” Clifton says. “So we had put in slightly upgraded engines and we wouldn’t be able to meet that at the time of proposals.”

The air force is also seeking a helicopter that can meet very hot, high altitude conditions for a three-hour mission, Clifton says. Much of the Huey’s mission guarding the air force’s Minuteman III missile silos is conducted in the USA’s far north, including two bases in North Dakota and Montana.

The remainder of the Huey’s tasks are focused on transporting political leaders out of Washington DC in the event of a nuclear attack, although it ferries VIPs during peacetime. The service’s concern about high and hot conditions centres on its third silo base at F.E. Warren AFB, Wyoming, Clifton says.

“They focused on worse case scenario and that was a summertime, hot day out of F.E. Warren,” he says. “Which is understandable, you can’t [only] plan to fly things out of Washington DC in the spring when it’s cool.”

Based on the air force’s requirements today, Bell would also modify the UH-1Y’s cabin to reach the new Huey’s payload and troop capacity needs. The payload and engine modifications would only mean a minor delay for Bell’s delivery, Clifton says.