While the YHC-1A would be improved and adopted by the U.S. Marine Corps as the CH-46 Sea Knight, the Army sought a heavier transport helicopter, and ordered an enlarged derivative of the V-107 with the Vertol designation Model 114.

The military version of the helicopter has been exported to nations across the world; the U.S. Army and the Royal Air Force (see Boeing Chinook (UK variants)) have been its two largest users.

It has been used by civil operators not only for passenger and cargo transport, but also for aerial firefighting and to support logging, construction, and oil extraction industries.

During late 1956, the United States Department of the Army announced its intention to replace the Sikorsky CH-37 Mojave, which was powered by piston engines, with a new, gas turbine-powered helicopter.

Following a design competition, in September 1958, a joint Army–Air Force source selection board recommended that the Army procure the Vertol-built medium transport helicopter.

Another faction in Army Aviation thought that the new helicopter should be much larger, enabling it to airlift large artillery pieces and possess enough internal space to carry the new MGM-31 "Pershing" missile system.

[9] The "sizing" of the Chinook was directly related to the growth of the Huey and the Army's tacticians' insistence that initial air assaults be built around the squad.

[10] The latest mainstream generation is the CH-47F, which features several major upgrades to reduce maintenance, digitized flight controls, and is powered by two 4,733-horsepower (3,529 kW) Honeywell engines.

[22] The German government announced in June 2022 that the CH-47F Block 2 was selected as the winner of its heavy helicopter program to replace its Sikorsky CH-53G Sea Stallion fleet.

[29] The most spectacular mission in Vietnam for the Chinook was the placing of artillery batteries in perilous mountain positions inaccessible by any other means, and then keeping them resupplied with large quantities of ammunition.

[citation needed] Pilots discovered the CH-47A's transmission system could not handle the two gas turbines running at full power, and high humidity and heat reduced the maximum lift by more than 20% in the low lands and 30% in mountain areas.

The CH-47s in Vietnam were generally armed with a single 0.308 in (7.62 mm) M60 machine gun on a pintle mount on either side of the aircraft for self-defense, with stops fitted to keep the gunners from firing into the rotor blades.

[33] During the 1970s, the U.S. and Iran had a strong relationship, in which the Iranian armed forces began to use many American military aircraft, most notably the F-14 Tomcat, as part of a modernization program.

In 2002, Libya sold 16 helicopters to the United Arab Emirates, as due to the Western embargo and lack of funds, maintaining them was difficult.

Of the Army's aircraft, one was destroyed on the ground by 30 mm cannon fire from an RAF GR3 Harrier, while the other was captured by the British and reused after the war.

[59][60] Its lift capacity has been found of particular value in the mountainous terrain of Afghanistan, where high altitudes and temperatures limit the use of helicopters such as the UH-60 Black Hawk; reportedly, one Chinook can replace up to five UH-60s in the air assault transport role.

[61] The Chinook helicopters of several nations have participated in the Afghanistan War, including aircraft from Britain, Italy, the Netherlands, Spain, Canada, and Australia.

The previous biggest single-day loss for American forces in Afghanistan involved a Chinook that was shot down near Kabul in Kunar Province in June 2005 with all aboard killed, including a 16-member U.S. Special Operations team.

The Chinooks arrived at Miami-Opa Locka Executive Airport, just outside of the disaster zone, one day after the President's order; early on, they performed a wide loop over Homestead and Florida City to publicly display their presence, helping to curtail lawlessness and looting.

[71][72] The Chinooks initially flew twelve sorties per day out of Opa Locka, which expanded over time, often supporting distribution operations at Homestead AFB and Opa Locka, as well as delivering relief payloads via internal storage, not using sling loads, supplementing the two dozen distribution centers and trucks, proving essential as trucks could not reach the worst hit areas due to downed trees and power lines.

They flew everyday for approximately three weeks, moving supplies and personnel around the disaster zone as well as carrying media and government officials, including then Congressman Bill Nelson.

[71] Three of Japan's CH-47s were used to cool Reactors 3 and 4 of the Fukushima Nuclear power plant following the 9.0 earthquake in 2011; they were used to collect sea water from the nearby ocean and drop it over the affected areas.

Since the type's inception, the Chinook has carried out various secondary missions, including medical evacuation, disaster relief, search and rescue, aircraft recovery, fire fighting, and heavy construction assistance.

Rare newsreel footage shows one of the aircraft in action supporting the 8th Cavalry Regiment during an ambush at Bông Son, South Vietnam.

The "Super C" had Lycoming T55-L-11 engines delivering 3,750 shp (2,800 kW), an upgraded maximum gross weight of 46,000 lb (21,000 kg), and pitch stability augmentation.

Receiving the Canadian designation "CH-147", these were fitted with a power hoist above the crew door; other changes included a flight engineer station in the rear cabin: operators referred to the configuration as the "Super C".

[109] The milled construction reduces vibration, as well as inspection and repair needs, and eliminates flexing points to increase service life.

[113][114] The Advanced Chinook Rotor Blades (ACRB), derived from the cancelled RAH-66 Comanche, were intended to improve lift performance in hot/high altitude conditions by 900 kg (2,000 lb); however, the US Army ultimately decided against implementing the ACRB due to persistent vibration during testing, Boeing denied the assertion that the vibration was a safety risk and believed it could be solved with dampeners.

[134] Due to budget issues, technical problems and delays with CH-53K, the director of the Pentagon's cost assessment office directed US Navy to consider maritime versions of CH-47.

[140] Data from Boeing CH-47,[202] Army Chinook file, CH-47F,[203] International Directory, CH-47D[204]General characteristics Performance Armament Avionics Related development Aircraft of comparable role, configuration, and era