The US Air Force has released a draft request for proposals to replace its UH-1N Hueys, calling for a full and open to procure up to 84 helicopters.

Three months after the USAF reset the Huey replacement programme with a new request for information released in September, the service is forging ahead with its first draft RFP.

The air force has called for the replacement helicopter to be able to carry at least nine combat troops plus equipment at a speed of at least 135kt. In September, the USAF’s acquisition chief clarified that the replacement Hueys would not be required to carry more than nine troops.

The aircraft must also achieve an unrefuelled minimum range of 225nm (407) with a 3h endurance, according to USAF.

After initially considering a sole-source buy of Sikorsky UH-60M Black Hawks, the service announced earlier this year it would move ahead with an open competition. Both the USAF’s recent announcement and the annual defence policy bill state the service will conduct a full and open competition.

The competition is likely to invite at least four bids — UH-60M, Airbus UH-72A Lakotas, Leonardo AW139 and Bell Helicopter UH-1Y.

The long-delayed recapitalisation programme will replace the USAF’s inventory of 59 Vietnam-era UH-1N Huey helicopters that support the service’s nuclear intercontinental ballistic missile bases in Wyoming, Montana and North Dakota.