View source for H-1 upgrade program

[[File:170602-N-RC734-116.jpg|thumb|Upgraded H-1 family in flight]]
The '''H-1 upgrade program''' is the [[United States Marine Corps]]'s program to develop the [[AH-1Z Viper]] and [[UH-1Y Venom]] military helicopters to replace its aging fleets of [[AH-1W SuperCobra]]s and [[UH-1N Twin Huey]]s. The contract was awarded in 1996 to [[Bell Helicopter]], the original manufacturer of both aircraft, to design the new airframes as modernized [[attack helicopter|attack]] and [[utility helicopter]]s with considerable design commonality, to reduce operating costs.

The upgraded type entered service starting in the early 2000s, and have become the dominant type in the USMC as the older models were slowly phased out. The upgraded types have also been exported internationally. 

==Development==
[[File:UH-1Y lands on HMAS Canberra.jpg|thumb|UH-1Y and AH-Z land on ship deck]]
[[File:AH-1Z and UH-1Y during trials on USS Bataan (LHD-5) 2005.JPG|thumb|right|An AH-1Z Viper and a Bell UH-1Y Venom during trials aboard the USS ''Bataan'' (LHD-5) in 2005]]

In August 1995, the [[United States Secretary of the Navy|Secretary of the Navy]] authorized the Marine Corps to upgrade its utility and attack helicopters as a bridge until the [[Joint Replacement Aircraft]] was available in 2020.<ref name="globalsecurity">[http://www.globalsecurity.org/military/systems/aircraft/uh-1-upgrades.htm H-1 Upgrade Program] on GlobalSecurity.org</ref> In 1996, the Marine Corps launched the H-1 upgrade program by signing a contract with Bell for upgrading 180 AH-1Ws into AH-1Zs and upgrading 100 UH-1Ns into UH-1Ys.<ref name="mod_battle">Donald, David. ''Modern Battlefield Warplanes''. AIRTime Publishing, 2004. {{ISBN|1-880588-76-5}}.</ref><ref name="Huey_Cobra">Bishop, Chris. ''Huey Cobra Gunships''. Osprey Publishing, 2006. {{ISBN|1-84176-984-3}}.</ref> While the original contract called for upgrading existing airframes, it was later modified in 2008 to manufacture completely new aircraft.<ref name="mod_battle"/><ref name="Ynew">{{cite web|url=http://www.news.navy.mil/search/displaybbs.asp?bbs_id=1332&cat=5 |title=UH-1Ys to be built new starting in 06 |last=Milliman |first=John |date=2005-04-22 |work=[[Naval Air Systems Command]] |publisher=[[United States Navy]] |access-date=2008-12-06 |url-status=dead |archive-url=https://web.archive.org/web/20090206153717/http://www.news.navy.mil/search/displaybbs.asp?bbs_id=1332&cat=5 |archive-date=2009-02-06 }}</ref><ref name="Znew">Warwick, Graham. [http://www.flightglobal.com/articles/2008/02/15/221550/bell-ah-1z-upgrade-to-switch-to-new-airframes.html "Bell AH-1Z upgrade to switch to new airframes"], Flightglobal.com, 15 February 2008.</ref> The program also includes aircraft simulators.<ref name="asti">[http://www.asti-usa.com/news/2005/0909a.html USMC H-1 Upgrade Program] {{webarchive |url=https://web.archive.org/web/20081212212620/http://www.asti-usa.com/news/2005/0909a.html |date=December 12, 2008 }}, Advanced Simulation Technology, Inc., September 2005</ref>
The AH-1Z first flew on 8 December 2000.<ref>[http://www.helis.com/news/2000/ah1zff.htm "AH-1Z completes first flight"], Bell Helicopter, 7 December 2000.</ref> Three prototype aircraft were delivered to [[Naval Air Systems Command|NAVAIR]]'s [[Naval Air Station Patuxent River]] in July 2002 for the flight test phase of the program. [[Low rate initial production|Low-rate initial production]] followed beginning in October 2003,<ref name="mod_battle"/><ref>[http://findarticles.com/p/articles/mi_m0EIN/is_2003_Oct_23/ai_109188407 Defense Dept. `Green Lights' Bell's H-1 Upgrade Program] [[Business Wire]], October 2003</ref> with deliveries to run through 2018,<ref>[https://web.archive.org/web/20081230094458/http://pao.navair.navy.mil/press_releases/index.cfm?fuseaction=home.view&Press_release_id=3440&site_id=17 "AH-1Z/UH-1Y complete developmental testing"], US Navy, 6 March 2006.</ref> however, full-rate production was delayed until 2005.<ref name="globalsecurity" />

The AH-1Z completed sea-trial flight testing in May 2005.<ref>[http://pma276public.navair.navy.mil/pma276public/newsArticle.asp?itemID=37 "AH-1Z/UH-1Y complete first sea trials"] {{webarchive |url=https://web.archive.org/web/20080215193227/http://pma276public.navair.navy.mil/pma276public/newsArticle.asp?itemID=37 |date=February 15, 2008 }}. US Navy, 13 June 2005.</ref> On 15 October 2005, the USMC, through the Naval Air Systems Command, accepted delivery of the first AH-1Z production helicopter to enter the fleet.<ref>[http://www.janes.com/aerospace/military/news/jhms/jhms051207_1_n.shtml "Bell 449 SuperCobra and KingCobra"], Jane's Information Group, 7 December 2005.</ref> During the first quarter of 2006, the first production model UH-1Y completed its first flight, and the aircraft were transferred to the Operational Test Unit at the NAS Patuxent River to begin operational evaluation (OPEVAL) testing.<ref>[https://web.archive.org/web/20081230102420/http://pao.navair.navy.mil/press_releases/index.cfm?fuseaction=home.view&Press_release_id=3485&site_id=17 "AH-1Z/UH-1Y Start OPEVAL"], US Navy, 6 May 2006.</ref> In February 2008, Bell received a contract for the last 40 AH-1Zs to be built as new airframes instead of the previously planned rebuild of AH-1Ws.<ref name="Znew" /> Also that same month, the AH-1Z and UH-1Y began the second and final portion of OPEVAL testing.<ref>Warwick, Graham. [http://www.flightglobal.com/articles/2008/02/20/221714/pictures-us-marine-corps-bell-ah-1z-and-uh-1y-enter-final-test-phase.html "US Marine Corps' Bell AH-1Z and UH-1Y enter final test phase"], Flightglobal.com, 20 February 2008.</ref>

Bell delivered three upgraded H-1s to the Marine Corps in February 2008.<ref name="H-1_Feb2008">[http://www.bellhelicopter.com/en/company/pressReleases/PR_08_0305_threeH-1Delivered.cfm "Bell H-1 upgrade program delivers two UH-1Y and one AH-1Z in February"] {{webarchive |url=https://web.archive.org/web/20081028131414/http://www.bellhelicopter.com/en/company/pressReleases/PR_08_0305_threeH-1Delivered.cfm |date=October 28, 2008 }}. Bell Helicopter, 3 March 2008.</ref> In September 2008, the NAVAIR proposed adding 46 additional AH-1Zs bringing the total number ordered to 226. The additional aircraft will appear on the 2010 fiscal budget request.<ref name="increase">{{cite web|last=Trimble|first=Stephen|title=US Navy proposes more UH-1Ys, AH-1Zs despite test phase setback|publisher=www.flightglogal.com|date=2008-08-22|url=http://www.flightglobal.com/articles/2008/08/22/315087/us-navy-proposes-more-uh-1ys-ah-1zs-despite-test-phase.html|accessdate=2008-08-24}}</ref> The final number of UH-1Y acquisitions was also set at 123.<ref name="gearbox" />  Full-rate production was approved in late 2008.<ref name="production" />

On September 30, 2008, Bell received a contract for Lot 5 H-1 aircraft. These 15 aircraft in Lot 5 include 11 UH-1Ys and four AH-1Zs, bringing the total contracted number to 49 upgraded H-1 aircraft for the Marine Corps: 37 UH-1Ys and 12 AH-1Zs. At that time, the company had delivered 20 upgraded H-1 helicopters: 14 UH-1Ys and six AH-1Zs.<ref>{{cite news|url=http://phx.corporate-ir.net/phoenix.zhtml?c=110047&p=irol-newsArticle&ID=1208320&highlight=|archive-url=https://archive.today/20130221073138/http://phx.corporate-ir.net/phoenix.zhtml?c=110047&p=irol-newsArticle&ID=1208320&highlight=|url-status=dead|archive-date=February 21, 2013|title=Bell Helicopter Receives Contract for Additional H-1 Aircraft|date=October 10, 2008|work=[[Textron]]}}</ref><ref>{{cite news|url=http://www.deagel.com/news/Bell-Helicopter-Receives-Contract-for-Lot-5-H-1-Aircraft_n000005164.aspx|title=Bell Helicopter Receives Contract for Lot 5 H-1 Aircraft |date=September 30, 2008|work=[[deagel.com]]}}</ref> On March 27, 2009, the Navy Department ordered 16 Lot 6 H-1 helicopters. The 16 aircraft in Lot 6 include five AH-1Zs and 11 UH-1Ys, bringing the total contract to produce a total of 65 upgraded H-1 aircraft: 17 AH-1Zs and 48 UH-1Ys. At the time, Bell had delivered 23 upgraded H-1 helicopters: six AH-1Zs and 17 UH-1Ys.<ref>{{cite news|url=http://phx.corporate-ir.net/phoenix.zhtml?c=110047&p=irol-newsArticle&ID=1273677&highlight=|archive-url=https://archive.today/20120712100347/http://phx.corporate-ir.net/phoenix.zhtml?c=110047&p=irol-newsArticle&ID=1273677&highlight=|url-status=dead|archive-date=July 12, 2012|title=US Navy Orders More H-1 Aircraft from Bell Helicopter|date=April 2, 2009|work=[[Textron]]}}</ref><ref>{{cite news|url=http://www.deagel.com/news/US-Navy-Orders-16-Lot-6-UH-1Y-Helicopters_n000005896.aspx|title=US Navy Orders 16 Lot 6 UH-1Y Helicopters |date=March 27, 2009|work=[[deagel.com]]}}</ref>

In May 2009, several helicopters were grounded after a manufacturer's defect was detected in the [[gearbox]].<ref name="gearbox">{{cite news|url=http://marinetimes.com/news/2009/05/marine_grounding_050309w/|title=Damaged gear boxes ground some new Hueys|last=McCullough|first=Amy|date=May 5, 2009|work=[[Marine Corps Times]]|publisher=[[Gannett Company]]|access-date=2009-05-22|archive-url=https://archive.today/20130128124552/http://marinetimes.com/news/2009/05/marine_grounding_050309w/|archive-date=January 28, 2013|url-status=dead|df=mdy-all}}</ref> The aircraft deployed with the [[13th Marine Expeditionary Unit]] were not affected.

In September 2009, the UH-1Y entered full rate production, with the Marine Corps expected to receive 21 aircraft by the end of the year.<ref name="production">{{cite news|url=http://www.aviationtoday.com/rw/military/attack/Program-Insider-H-1-Update_34824.html|title=Program Insider: H-1 Update|date=September 1, 2009|work=[[Rotor & Wing Magazine]]|access-date=September 19, 2009|archive-date=February 17, 2012|archive-url=https://web.archive.org/web/20120217023904/http://www.aviationtoday.com/rw/military/attack/Program-Insider-H-1-Update_34824.html|url-status=dead}}</ref>  The AH-1Z reached [[Initial Operational Capability|initial operational capability]] in September 2010,<ref>{{cite web |url= http://www.flightglobal.com/articles/2010/09/30/348003/usmc-declares-ah-1z-viper-combat-ready.html |author= Trimble, Stephen |title= USMC declares AH-1Z Viper combat ready |publisher= Flight International |date= 30 September 2010 |accessdate= 1 October 2010}}</ref>  and was approved to begin full-rate production on 10 December 2010.<ref name="Full-rate production">{{cite web|title=Bell Helicopter AH-1Z earns Navy approval for full rate production |url=http://www.shephard.co.uk/news/rotorhub/bell-helicopter-ah-1z-earns-navy-approval-for-full-rate-production/7907/ |publisher=Shephard Group Limited |access-date=11 December 2010 |date=10 December 2010 |url-status=dead |archive-url=https://web.archive.org/web/20101216031211/http://www.shephard.co.uk/news/rotorhub/bell-helicopter-ah-1z-earns-navy-approval-for-full-rate-production/7907/ |archive-date=16 December 2010 }}</ref><ref>{{cite web|url=http://www.defenseindustrydaily.com/snakes-rotors-usmc-h-1-helicopter-program-03541/ |title=Snakes and Rotors: The USMC's H-1 Helicopter Program |publisher=Defense Industry Daily |date= 30 December 2010 |accessdate= 2 January 2011}}</ref>  The AH-1Z is expected to cost approximately {{USD|27 million}} each.<ref name="flightglobal">[http://www.flightglobal.com/articles/2010/12/20/351056/cutaway-ah-1z-viper-enters-production-as-substantially-new-aircraft.html "AH-1Z Viper enters production as substantially new aircraft."] ''[[FlightGlobal]]'', 20 December 2010.</ref>

Program manager Colonel Harry Hewson expressed interest in exporting the upgraded aircraft via [[Foreign Military Sales]] at the 2010 [[Farnborough Airshow]].<ref>{{cite news|title=Corps seeks international buyers for its new helos|last=Peniston|first=Bradley|date=August 2, 2010|newspaper=[[Marine Corps Times]]|pages=19}}</ref>

==Upgrades==
[[File:UH-1Y.jpg|thumb|UH-1Y landing on an amphibious assault ship]]
[[File:170312-M-MI258-080.jpg|thumb|AH-1Z and UH-1Y in Japan]]

The stated mission of the H-1 upgrade program is to "resolve existing safety deficiencies, significantly improve operational capabilities, and reduce life-cycle costs. Commonality between aircraft will greatly enhance the maintainability and deployability of the systems with the capability to support and operate both aircraft within the same squadron structure."<ref name="concepts">[http://hqinet001.hqmc.usmc.mil/p&r/concepts/2007/PDF/Chapter%203/Part%203/C&P2007Chap3%20Part3%20Aviation%20Combat%20Element%20Pg183%20H-1%20Upgrade%20Program%20(UH-1Y%20AH-1Z).pdf H-1 Upgrade Program (UH-1Y/AH-1Z)] {{webarchive|url=https://web.archive.org/web/20070710005737/http://hqinet001.hqmc.usmc.mil/p%26r/concepts/2007/PDF/Chapter%203/Part%203/C%26P2007Chap3%20Part3%20Aviation%20Combat%20Element%20Pg183%20H-1%20Upgrade%20Program%20%28UH-1Y%20AH-1Z%29.pdf |date=2007-07-10 }}, U.S. Marine Corps, 2007.</ref> Reduced [[Military logistics|logistical]] burden, maintenance costs, and personnel requirements (all of which increase the [[expeditionary warfare|expeditionary]] capabilities of the aircraft) are possible by the increased commonality of the two airframes,<ref name="flightglobal"/> as well as increased reliability of individual components.<ref name="globalsecurity" />

===Common Elements===
The AH-1Z and UH-1Y share a common tailboom, engines, rotor system, drivetrain, avionics architecture, software, controls and displays for over 84% identical components.<ref name="AH-1Z_guide">[http://www.bellhelicopter.com/en/aircraft/military/pdf/AH1Z_PG_3-06_web.pdf Bell AH-1Z Pocket Guide] {{webarchive |url=https://web.archive.org/web/20081113141415/http://www.bellhelicopter.com/en/aircraft/military/pdf/AH1Z_PG_3-06_web.pdf |date=November 13, 2008 }}, Bell Helicopter, Retrieved 3 January 2008.</ref><ref name="UH-1Y_guide">[http://www.bellhelicopter.com/en/aircraft/military/pdf/UH1Y_PG_3-06_web.pdf Bell UH-1Y pocket guide] {{webarchive |url=https://web.archive.org/web/20081114165501/http://www.bellhelicopter.com/en/aircraft/military/pdf/UH1Y_PG_3-06_web.pdf |date=November 14, 2008 }}, Bell Helicopter, Retrieved 16 August 2008.</ref> Both aircraft use twin [[General Electric T700]]-GE-401C [[turboshaft]] outputting 1,800 [[Horsepower#Shaft horsepower|shp]] (1,350&nbsp;kW) each. Upgrades will also be made to the [[Transmission (mechanics)|transmission]] (rated for {{convert|2350|hp|kW|abbr=on}}) and skid landing gear.<ref name="concepts" /><ref name="bh_AH-1Z_pg">[http://www.bellhelicopter.com/en/aircraft/military/bellAH-1Z.cfm Bell AH-1Z page] {{webarchive |url=https://web.archive.org/web/20070328222236/http://www.bellhelicopter.com/en/aircraft/military/bellAH-1Z.cfm |date=March 28, 2007 }}, Bell Helicopter, Retrieved 3 January 2008.</ref>

The existing two-bladed semi-rigid, teetering rotor system is being replaced with a four-bladed, hingeless, bearingless composite rotor system.<ref name="flightglobal"/> The improvement in flight characteristics provided by the four-bladed configuration has led to increases in flight envelope, maximum speed, vertical rate-of-climb, payload and  reduced rotor vibration.<ref name="af_tech">[http://www.airforce-technology.com/projects/supcobra/ AH-1W/AH-1Z Super Cobra Attack Helicopter, USA], Airforce-Technology.com. Retrieved: 14 January 2008.</ref>{{Unreliable source?|reason=domain on WP:BLACKLIST|date=June 2016}} The rotor system has 75% fewer parts than that of four-bladed articulated systems, and the improved yokes allow for weight saving with the elimination of all bearings, hinges, and vibration absorbers in the rotor hub.<ref name="flightglobal"/> The blades are made of [[carbon fiber]]-based composites, which have an increased ballistic survivability, and there is a semiautomatic folding system for stowage aboard [[Amphibious assault ship]]s.<ref name="AH-1Z_guide"/> Both helicopters will receive an upgraded, four-blade [[tail rotor]] and drive system.<ref name="concepts" />

The new integrated avionics system (IAS) has been developed by [[Northrop Grumman]].<ref name="concepts" /> The system includes two mission computers, an automatic flight control system (reportedly "stops short of a [[fly-by-wire]] system"<ref name="flightglobal"/>), and a [[glass cockpit]]; Bell suggests the system can withstand [[23 mm caliber]] fire.<ref name="flightglobal"/> Each crew station has two {{convert|8|by|6|in|cm|adj=on|abbr=on}} multifunction [[liquid crystal display]]s (LCD) and one {{convert|4.2|by|4.2|in|cm|abbr=on|adj=on}} dual function LCD display. The communications suite combines a US Navy RT-1824 integrated radio, UHF/VHF, COMSEC, and modem in a single unit.<ref name="asti" /> The navigation suite includes an embedded [[Global Positioning System|GPS]] inertial navigation system (EGI), a digital map system and a low-airspeed air data subsystem, which allows weapons delivery when hovering.<ref name="af_tech"/> The new cockpit systems will increase joint interoperability, now able to transmit and receive data from ground and air systems from other branches.<ref name="globalsecurity" /><ref name="concepts" />

The [[Lockheed Martin]] Target Sight System (TSS) incorporates a third-generation FLIR sensor.<ref name="concepts" /> The TSS provides target sighting in day, night or adverse weather conditions. The system has various view modes and can track with FLIR or by TV.<ref name="AH-1Z_guide"/> It is also used on the [[KC-130J]] [[Harvest HAWK]].<ref>[http://www.dvidshub.net/news/70647/hueys-harvest-hawk-ordnance-marine-arms-aircraft-afghanistan "From Hueys to Harvest Hawk: Ordnance Marine arms aircraft in Afghanistan"] by Cpl. Samantha H. Arrington, [[DVIDS]]. 19 May 2011</ref>

[[File:AH-1Z pilots with helmet mounted displays.jpg|thumb|AH-1Z pilots aboard the {{USS|Makin Island|LHD-8|6}} wear helmet-mounted displays]]

The pilot and copilot are equipped with the [[Thales Group|Thales]] "Top Owl" [[Helmet mounted display|helmet-mounted sight and display]] system.<ref name="UH-1Y_guide"/><ref name="bh_AH-1Z_pg"/> The Top Owl has a 24-hour day/night capability and a binocular display with a 40° field of view.  Its visor projection provides [[forward looking infrared]] (FLIR) or video imagery. However, the Corps has decided to augment it with existing [[night vision device]]s.<ref name="flightglobal"/>

===AH-1Z===
[[File:AH1Z at the MCAS Miramar Air Show on 3 Oct 2008.JPG|thumb|left|AH-1Z on the tarmac]]
Its two redesigned wing stubs are longer, with each adding a wingtip station for a missile such as the [[AIM-9 Sidewinder]].  Each wing has two other stations for {{convert|2.75|in|mm}} [[Hydra 70]] rocket pods, or [[AGM-114 Hellfire]] quad missile launchers. The Longbow radar can also be mounted on a wingtip station.<ref name="mod_battle"/> It will be able to cruise at approximately {{convert|135|to|140|kn|km/h}} and sprint at {{convert|180|kn|km/h}} before suffering the limits of [[parasitic drag]].<ref name="flightglobal"/>

The AH-1Z has survivability equipment including the Hover Infrared Suppression System (HIRSS) to cover engine exhausts, countermeasure dispensers, radar warning, missile warning, and laser warning systems.<ref name="AH-1Z_guide"/>

===UH-1Y===
[[File:Bell UH-1Y Venom (USMC) Pendleton 282.jpg|thumb|UH-Y from the rear, showing the distinctive exhaust common to both upgraded types]]
One of the most critical UH-1Y upgrades is in its [[powertrain]]. The UH-1N gradually became burdened with various upgrades: avionics, radios, modern door guns, and safety upgrades; all increasing the UH-1N's empty weight. With a maximum speed of approximately {{convert|100|kn|km/h}} and an inability to lift much more than its own crew, fuel and ammunition, the UH-1N became limited in its utility. However, the UH-1Y has upgraded engines and transmission, 170% increased payload, and almost 50% greater range and maximum speed.<ref name="UH-1Y_guide"/><ref name="bh_UH-1Y_pg">[http://www.bellhelicopter.com/en/aircraft/military/bellUH-1Y.cfm Bell UH-1Y page] {{webarchive |url=https://web.archive.org/web/20070403082131/http://www.bellhelicopter.com/en/aircraft/military/bellUH-1Y.cfm |date=April 3, 2007 }}, Bell Helicopter, Retrieved 3 January 2008.</ref> The fuselage has been lengthened by {{convert|21|in|cm}} just forward of the main door for more capacity.<ref name="UH-1Y_guide"/>

==Exports==
In 2013 the upgraded helicopters were being considered by South Korea and Iraq.<ref>[http://www.chicagotribune.com/business/sns-rt-us-textron-helicoptersbre90u1fu-20130131,0,4553044.story "Bell Helicopters' upgraded H-1 generates foreign interest."]</ref>

===AH-1Z Viper===
As of 2022, the Viper has been ordered by [[Royal Bahraini Air Force]] and the [[Czech Air Force]].<ref name = "Czech to2024">{{Cite web |url = https://www.verticalmag.com/news/czech-h-1-deal-will-keep-bells-production-line-open-at-least-through-2024/ |title = Czech H-1 deal will keep Bell's production line open at least through 2024 |publisher = verticalmag.com |first = Dan |last = Parsons |date = 16 December 2019 }}</ref> Bahrain has ordered 12 and the Czech Republic has ordered 4. 

Nigeria has also ordered the AH-1Z, and as of 2024 is planning procure 12.<ref>{{Cite web |last=Finnerty2024-03-13T17:00:00+00:00 |first=Ryan |title=Bell extends H-1 production with $455m attack helicopter order from Nigeria |url=https://www.flightglobal.com/helicopters/bell-extends-h-1-production-with-455m-attack-helicopter-order-from-nigeria/157360.article |access-date=2024-04-19 |website=Flight Global |language=en}}</ref>

===UH-1Y Venom===
The Venom, as of 2022, was ordered by the [[Czech Air Force]], who ordered 8 helicopters.{{cn|date=April 2024}}

==See also==
{{Commons category|AH-1Z Viper}}
{{Portal|Aviation}}
[[File:A U.S. Marine Corps UH-1Y Venom helicopter (right) and AH-1W Super Cobra helicopter of Marine Light Attack Helicopter Squadron 369 (HMLA-369) in flight, Forward Operating Base Edinburgh, Helmand Province 111209-M-CL319-101.jpg|thumb|AH-1Z Viper (''left'') and UH-1Y Venom (''right'')]]
{{aircontent
|see also=
* [[Bell Huey]]
* [[United States Marine Corps Aviation]]
* [[US Helicopter Armament Subsystems]]
|related=
* [[Bell 214]]
* [[Bell 412]]
* [[Bell AH-1 SuperCobra]]
* [[Bell UH-1N Twin Huey]]
* [[Bell YAH-63]]
|similar aircraft=
|lists=
* [[List of attack aircraft]]
* [[List of helicopters]]
* [[List of active military aircraft of the United States]]
}}

==References==
{{Reflist|2}}

==External links==
* {{cite web|url=http://hqinet001.hqmc.usmc.mil/p&r/concepts/2007/PDF/Chapter%203/Part%203/C&P2007Chap3%20Part3%20Aviation%20Combat%20Element%20Pg183%20H-1%20Upgrade%20Program%20(UH-1Y%20AH-1Z).pdf |title=H-1 Upgrade Program (UH-1Y/AH-1Z) |publisher=U.S. Marine Corps |year=2007 |archive-url=https://web.archive.org/web/20070710005737/http://hqinet001.hqmc.usmc.mil/p%26r/concepts/2007/PDF/Chapter%203/Part%203/C%26P2007Chap3%20Part3%20Aviation%20Combat%20Element%20Pg183%20H-1%20Upgrade%20Program%20%28UH-1Y%20AH-1Z%29.pdf |archive-date=2007-07-10 |url-status=dead }}
* [http://hqinet001.hqmc.usmc.mil/AVN/FY2009%20AVPLAN.pdf 2009 Aviation plan], U.S. Marine Corps, 2008{{Dead link|date=October 2010}}
* [https://web.archive.org/web/20040929031029/http://pma276public.navair.navy.mil/ PMA-276: USMC Light/Attack Helicopter Program web site]
* [https://web.archive.org/web/20081118040703/http://www.bellhelicopter.com/en/company/pressReleases/PR_060929_1230_H1Rollout.cfm "First Production H-1 Helicopters Rollout"], Bell Helicopter, 27 September 2006
* [https://web.archive.org/web/20080215193239/http://pma276public.navair.navy.mil/pma276public/newsArticle.asp?itemID=38 "New H-1s reach 3,000 hrs, prep for OpEval"], U.S. Marine Corps, 13 June 2005.
* [http://www.flightglobal.com/articles/2008/08/22/315087/us-navy-proposes-more-uh-1ys-ah-1zs-despite-test-phase.html "US Navy proposes more UH-1Ys, AH-1Zs despite test phase setback"], Flight International, 22 August 2008.
* [http://www.defenseindustrydaily.com/snakes-rotors-usmc-h-1-helicopter-program-03541/ Snakes and Rotors: The USMC’s H-1 Helicopter Program], Defense Industry Daily, 16 June 2010

{{Bell Aircraft}}
{{Huey family}}

{{DEFAULTSORT:H-1 Upgrade Program}}
[[Category:United States military helicopters]]
[[Category:Military aircraft procurement programs of the United States]]
[[Category:Helicopter procurement programs]]