The U.S. Army and Navy have largely replaced all their UH-1 transport helicopters. Only the Air Force still uses the UH-1, in the form of the twin-engine naval version. The air force has 62 UH-1Ns, used mainly for patrolling the large tracts of land containing ICBM silos. The main difference between the basic UH-1 and the UH-1N was the use of two engines in the latter. This made the five ton UH-1N safer and more reliable, which was the main reason the air force went with this model. The UH-1N could also carry a few more passengers. The air force is looking for 93 new helicopters to replace the UH-1Ns.
The half century old UH-1 ("Huey") is fading away. Over 16,000 UH-1s were built, and over 4,000 were lost during the Vietnam war. Over two thousand UH-1s are still in service. The 4.3 ton, single engine, UH-1 could carry two crew and eleven troops, and was the first military helicopter to use gas turbine (jet) engines. This allowed a lighter helicopter to carry more weight. The UH-1 served the army for fifty years, although since the 1990s, most served in reserve units. The twin engine UH-1 was originally developed for the Canadian military, and later adopted by the U.S. Navy, Marines and many foreign countries who were willing to pay a premium for the twin engines.
Most of the American UH-1s were replaced by the UH-60 in the 1980s. This 10.6 ton helicopter could carry more weight, and was safer to operate. Recently, the 3.6 ton UH-145 was introduced, and this replaces the remaining UH-1s in army service. The UH-1 was actually a military version of a civilian helicopter (Bell 204) design. Both remained in production through the 1980s, with over 12,000 204/205s being produced.
The U.S. Marine Corps still uses the UH-1N. But the marines have a remanufacturing program for them, which will convert UH-1Ns to UH-1Ys. Eventually a hundred UH-1Ns will be rebuilt at a cost of about $4 million each. New rotors, rebuilt airframes and new electronics will make the aircraft more capable, and eventually bring maintenance cost savings of about $14 million per aircraft. Part of this is achieved by installing sturdier and more reliable components. The marines expect the refurbished aircraft to be as effective as the successors to these designs (the UH-60.) For the marines, this is probably true. Marines don't have to move their helicopters as far, or carrying as much, as the army does. So for most jobs, the older helicopters, with new engines and electronics, can do the job just as well, without the longer range and greater carrying capacity of the UH-60.