The Army finally settled on the larger Chinook as its standard medium transport helicopter and as of February 1966, 161 aircraft had been delivered to the Army. The 1st Cavalry Division had brought their organic Chinook battalion with them when they arrived in 1965 and a separate aviation medium helicopter company, the 147th, had arrived in Vietnam on 29 November 1965. This latter company was initially placed in direct support of the 1st Infantry Division.
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. The 1st Cavalry Division found that its CH-47s were limited to a 7,000-pound (3,200 kg) payload when operating in the mountains, but could carry an additional 1,000 pounds (450 kg) when operating near the coast. The early Chinook design was limited by its rotor system which did not permit full use of the installed power, and users were anxious for an improved version which would upgrade this system.
As with any new piece of equipment, the Chinook presented a major problem of "customer education". Commanders and crew chiefs had to be constantly alert that eager soldiers did not overload the temptingly large cargo compartment. It would be some time before troops would be experts at using sling loads. The Chinook soon proved to be such an invaluable aircraft for artillery movement and heavy logistics that it was seldom used as an assault troop carrier. Some of the Chinook fleet were used for casualty evacuation, due to the very heavy demand for the helicopters they were usually overburdened with wounded. Perhaps the most cost effective use of the Chinook was the recovery of other downed aircraft.
The CH-47s are generally armed with a single 7.62-millimeter M60 machine gun on a pintle mount on either side of the machine for self-defense, with stops fitted to keep the gunners from firing into the rotor blades. Dust filters were also added to improve engine reliability. At its peak employment in Vietnam, there were 22 Chinook units in operation. Of the nearly 750 Chinook helicopters in the U.S. and South Vietnam fleets, about 200 were lost in combat or wartime operational accidents. The U.S. Army CH-47s supported the 1st Australian Task Force as required.
During the 1970s, the United States 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. After an agreement signed between Boeing and Elicotteri Meridionali, the Imperial Iranian Air Force purchased 20 Elicotteri Meridionali-built CH-47Cs in 1971. The Imperial Iranian Army Aviation purchased 70 CH-47Cs from Elicotteri Meridionali between 1972 and 1976. In late 1978, Iran placed an order for an additional 50 helicopters with Elicotteri Meridionali, but that order was canceled immediately after the revolution; but 11 of them were delivered after multiple requests by Iran.
In the 1978 Iranian Chinook shootdown, four Iranian CH-47Cs penetrated 15–20 km into Soviet airspace in the Turkmenistan Military District. They were intercepted by a MiG-23M which shot down one, killing eight crew members, and forced a second one to land. Chinook helicopters were used in efforts by the Imperial Iranian loyalist forces to resist the 1979 Iranian revolution.
During the Iran–Iraq War, Iran made heavy use of its US-bought equipment, and lost at least 8 CH-47s during the 1980–1988 period; most notably during a clash on 15 July 1983, when an Iraqi Mirage F1 destroyed three Iranian Chinooks transporting troops to the front line, and on 25–26 February 1984, when Iraqi MiG-21 fighters shot down two examples.
Despite the arms embargo in place upon Iran, it has managed to keep its Chinook fleet operational. Some of the Chinooks have been rebuilt by Panha. Currently 20 to 45 Chinooks are operational in Iran.
The Chinook was used both by Argentina and the United Kingdom during the Falklands War in 1982. The Argentine Air Force and the Argentine Army each deployed two CH-47C helicopters, which were widely used in general transport duties. Of the Army's aircraft, one was destroyed on the ground by a Harrier while the other was captured by the British and reused after the war. Both Argentine Air Force helicopters returned to Argentina and remained in service until 2002.
Afghanistan and Iraq wars
Approximately 163 CH-47Ds of various operators were deployed to Saudi Arabia, Kuwait and Iraq during Operation Desert Shield and the subsequent Operation Desert Storm in 1990–91.
The CH-47D has seen wide use in Operation Enduring Freedom in Afghanistan and Operation Iraqi Freedom in Iraq. The Chinook is being used in air assault missions, inserting troops into fire bases and later bringing food, water, and ammunition. It is also the casualty evacuation (casevac) aircraft of choice in the British Armed Forces. In combat theaters, it is typically escorted by attack helicopters such as the AH-64 Apache for protection. 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 UH-60 Black Hawk; reportedly, one Chinook can replace up to five UH-60s in the air assault transport role.
The Chinook helicopters of several nations have participated in the Afghanistan War, including aircraft from Britain, Italy, the Netherlands, Spain, Canada, and Australia. Despite the age of the Chinook, it is still in heavy demand, in part due its proven versatility and ability to operate in demanding environments such as Afghanistan
On 6 August 2011, a Chinook crashed near Kabul killing all of the 38 aboard. It was reportedly shot down with a rocket-propelled grenade by the Taliban. The 38 were members of NATO and allied forces, including about 30 U.S. special forces and seven Afghan troops. 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 the death of all aboard, including a 16-member U.S. Special Operations team.
In May 2011 an Australian Army CH-47D crashed during a resupply mission in Zabul Province, resulting in one fatality and five survivors. The helicopter was unable to be recovered and was destroyed in place. To compensate for the loss, the ADF added two ex-U.S. Army CH-47Ds to the fleet which are expected to be in service until the introduction of the CH-47Fs in 2016.
Disaster relief and other roles
Since the type's inception, the Chinook has carried out secondary missions including medical evacuation, disaster relief, search and rescue, aircraft recovery, fire fighting, and heavy construction assistance. According to Suresh Abraham, the Chinook's ability to carry large underslung loads has been of significant value in relief operations in the aftermath of natural disasters. Chinooks operators have often deployed their fleets overseas to support humanitarian efforts in stricken nations; Chinooks of the Republic of Singapore Air Force assisted in relief operations in neighboring Indonesia following the 2004 Asian Tsunami, and after the 2005 Kashmir earthquake the Royal Air Force dispatched Chinooks to Northern Pakistan to assist in recovery efforts.
Three Japanese CH-47s were used to cool Reactors 3 and 4 of the Fukushima Nuclear power-plant with sea water after the 9.0 earthquake in 2011; to protect the crew from heightened radiation levels, lead plates were attached to the floor.