Editing Boeing CH-47 Chinook (section)

===Vietnam War===
[[File:1st Cavalry troops deploy from CH-47, Operation Masher, February 1966.jpg|thumb|Soldiers depart a CH-47 during [[Operation Masher]] in 1966.]]

The Army finally settled on the larger Chinook as its standard medium-transport helicopter, and by February 1966, 161 aircraft had been delivered to the Army. The [[1st Cavalry Division (United States)|1st Cavalry Division]] had brought its organic Chinook battalion (three Chinook companies) when it arrived in 1965 and a separate aviation medium helicopter company, the 147th, had arrived in Vietnam on 29 November 1965.<ref>{{cite news |url= http://select.nytimes.com/gst/abstract.html?res=F40D10FF3C5A157A93C3A81783D85F418685F9 |title= Chinook Copter to Vietnam |work= The New York Times |date= 11 August 1965 |access-date= 29 March 2010 |archive-url= https://web.archive.org/web/20121103000428/http://select.nytimes.com/gst/abstract.html?res=F40D10FF3C5A157A93C3A81783D85F418685F9 |archive-date= 3 November 2012 |url-status= live}}</ref> This latter company was initially placed in direct support of the [[1st Infantry Division (United States)|1st Infantry Division]]. CH-47 crews quickly learned to mount an [[M60 machine gun]] in each of the forward doors. Sometimes they also installed an [[M2 Browning|M2]] machine gun to fire from the rear cargo door.<ref>{{Cite web|url=https://www.historynet.com/arsenal-ch-47c-chinook-helicopter.htm|title = Arsenal|date = 21 April 2017}}</ref>

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.<ref name="Tolsonarmy"/> The 1st Cavalry Division found that its CH-47s were limited to a {{convert|7000|lb|adj=on}} payload when operating in the mountains, but could carry an additional {{convert|1000|lb}} when operating near the coast.<ref name="Tolsonarmy"/>

[[File:NARA photo 111-CCV-569-CC50045.jpg|thumb|left|A CH-47A delivers a water trailer, 1967.]]
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.<ref name="Tolsonarmy"/> 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 was used for casualty evacuation, and due to the very heavy demand for the helicopters, they were usually overburdened with wounded.<ref>{{cite journal |title= Hardships and Personal Strategies of Vietnam War Nurses |first= Elizabeth A. |last= Scannell-Desch |author2= Marion Anderson |journal= Western Journal of Nursing Research |volume= 22 |number= 5 |pages= 526–550 |year= 2000 |doi= 10.1177/01939450022044584 |pmid= 10943170|s2cid= 41787367}}</ref> Perhaps the most cost effective use of the Chinook was the recovery of other downed aircraft.<ref>{{cite book |url= https://books.google.com/books?id=lXZuAAAAMAAJ |title= Vietnam choppers: helicopters in battle 1950–75 |first= Simon |last= Dunstan |publisher=Osprey Publishing |year= 2003 |page= 81|isbn= 978-0-85045-572-4}}</ref>

At the war's peak the US Army had 21 Chinook companies in Vietnam.{{citation needed|date=November 2020}} 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. More powerful, improved transmission and strengthened fuselages arrived in 1968 with the CH-47B, followed a few months later by the CH-47C. The CH-47s in Vietnam were generally armed with a single 0.308&nbsp;in ([[7.62×51mm NATO|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. Dust filters were also added to improve engine reliability. Of the nearly 750 Chinook helicopters in the U.S. and South Vietnam fleets, about 200 were lost in combat or wartime operational accidents.<ref>Anderton, David & Miller, Jay – Boeing Helicopters CH-47 Chinook. Arlington: Aerofax, Inc, 1989, p. 8. {{ISBN|0-942548-42-6}}.</ref> The U.S. Army CH-47s supported the [[1st Australian Task Force]] as required.

[[File:Ch47-chinook-vietnam.jpg|thumb|Troops unload from a CH-47 in the Cay Giep Mountains, Vietnam, 1967.]]
Four CH-47s were converted into ACH-47As by adding armor and improved engines. Its armament included two fixed forward firing [[Hispano-Suiza HS.404|M24A1 20&nbsp;mm cannons]], one turret with 40&nbsp;mm automatic grenade launcher on the nose, five .50 in machine guns and two weapon pods on the sides that could carry either [[Fin-Folding Aerial Rocket#Common Mk 40 FFAR Launchers|XM159B/XM159C]] 70&nbsp;mm rocket launchers or 7.62&nbsp;mm miniguns. They arrived in Vietnam in 1966, and they engaged in six months of operational testing at [[Camp Radcliff|An Khê Army Airfield]]. They performed well in combat, but its high maintenance costs and demand for use in troop and cargo transport was stronger. Three ACH-47s were lost. One collided with a CH-47 while taxiing. Another had a retention pin shake loose on a 20&nbsp;mm cannon and was brought down when its own gun fired through the forward rotor blades. The third was grounded by enemy fire and destroyed by enemy mortar rounds after the crew escaped.<ref>{{Cite web|url=https://www.businessinsider.com/this-monster-aircraft-was-the-helicopter-version-of-the-ac-130-gunship-2015-9?r=US&IR=T|title = This monster aircraft was the helicopter version of the AC-130 gunship|website = [[Business Insider]]}}</ref>