South Korea sought to upgrade 17 of its elderly CH-47D transport helicopters to the CH-47F standard and discovered they were too late to do that at less cost than just buying new CH-47Fs. At this time upgrading 17 CH-47Ds would cost 10 percent more than just buying new CH-47Fs. Most of the 47D to 47F upgrades were completed over five years go and many of the replacement components are no longer in production. Such components can be manufactured in small batches at greater cost but that drives up the cost of upgrades from D to F, and few CH-47 users bother with upgrading decades old D models when they can the newly built CH-47Fs more quickly and at less cost. South Korea is also uncertain if they should just buy the existing Block 1 CH-47F or wait for the Block 2. That is a problem because no delivery date or price has been decided on for Block 2. It is expected to be available by 2025 at the latest and will cost more than the current Block 1.
South Korea has been acquiring and using CH-47s since the late 1960s, six years after the first CH-47s were available. Since then South Korea found that the D model, which appeared in the early 1990s, did what was needed and upgraded its older CH-47s to the D standard and kept buying new or used CH-47Ds. For example, in 2014 South Korea bought 14 American CH-47Ds that were stationed in South Korea, along with all their spare parts and maintenance equipment. South Korea paid $130 million for all that, increasing the South Korean army and air force CH-47D fleet to 43 helicopters. That was a good deal for the Americans because it would cost about a million dollars to transport each of the older CH-47Ds back to the U.S., or about the same amount to scrap them. It was a good deal for the South Koreans because the used CH-47Ds had been well maintained and were obviously acclimated to operations in South Korea. The real bargain came in acquiring all the spare parts and maintenance equipment the Americans had in South Korea. Much of the “cost per aircraft” for new helicopters is the necessary spares and maintenance gear needed to keep them operational.
The CH-47F helicopter was a major improvement over the D model and had its first combat experience in Afghanistan a decade ago. Twenty 47Fs underwent sustained experience in a combat zone for a year (2009-2010), and performed well. The 20 CH-47Fs were used a lot, often flying eight missions a day, day after day. The CH-47Fs had a 90 percent availability rate. Although the CH-47F has been flying since 2001, and were first delivered to the U.S. Army in 2006, it took a while to find an opportunity to send a trained 47F unit to a combat zone. It takes sustained use in a combat environment to smoke out the last bugs and maintenance problems. There were some problems with the flat panel displays, but these were quickly worked out. There were several other minor problems, mostly having to do with all the dust in the environment, and the temperature extremes. These were often below freezing in Winter, and over 45 degrees/113 Fahrenheit in Summer. This was tough on the maintainers and manufacturers' representatives initially, but after a year maintenance was no longer an issue. This is important, because in Afghanistan, the CH-47 is a critical form of air transportation, including combat assault.
Early on the U.S. Army found that using its UH-60 "Blackhawk" helicopter for combat assault missions was not very effective in Afghanistan where many of these missions were carried out a high-altitudes which greatly reduced the performance of the UH-60. In Afghanistan the larger CH-47 Chinook was initially just used just for moving cargo and personnel from one base to another. But the army found that, in the high altitudes of Afghanistan, the more powerful CH-47 was often the only way to go in the thin mountain air. While doing that, the army found that the CH-47 made an excellent assault helicopter. In many ways, it was superior to the UH-60, mainly because the CH-47 carries more troops and moves faster and farther. The new CH-47F has even more powerful engines, and is even more valuable for high altitude assaults.
The Blackhawk can only carry eleven troops, and max speed is 285 kilometers an hour, with endurance of 2.1 hours. The CH-47F can carry ten tons of cargo, or up to 55 troops, and has a maximum range of 426 kilometers. Its max speed is 315 kilometers an hour. Typical missions last no more than 2.5 hours. This means that one CH-47 can carry 40-50 combat troops, and all their gear. For most air assaults, one CH-47 does the job that would otherwise require five UH-60s.
The first CH-47s entered service in 1962, able to carry only five tons. Some 750 served in Vietnam, and 200 of those were lost in action. Between 1982-94, 500 CH-47s were rebuilt to the CH-47D standard and many new CH-47Ds entered service. The CH-47F first entered flew in 2001, For the U.S. Army upgrades of CH-47Ds to the F standard as well as purchase of new CH-47Fs was largely completed by 2018. New CH-47Fs cost about $35 million each.
A CH-47D Block 2 is in development with availability sometime in the early 2020s. Payload will be increased about five percent to 10 tons and a new engine, rotor blades and other mechanical components would deliver greater lift and better hover performance under “hot and high (altitude)” conditions. The new powerplant equipment also provided more electrical power and greater range. The fuselage makes use of many lighter composite components. Metal armor will be replaced by lighter and more effective composite panels. Max takeoff weight would increase from 22.6 tons to 24.5 tons. A Block 3 model is also in the works and it will include a new engine design that is more powerful and reliable. There will be several other component improvements. Block 3 is expected to be available by 2030. Efforts to develop a new medium transport helicopter to replace the CH-47 keep running into the fact that they cannot improve on the constantly upgraded CH-47. Currently the U.S. Army believes improved CH-47s will remain in service until at least 2060. As of 2020 over 1,300 CH-47s have been produced and production of new models is expected to continue into the 2030s and upgrades a decade or more after that.