Editing M109 howitzer (section)

==Derivatives==

===M992===
{{Main|M992 field artillery ammunition supply vehicle}}
[[File:M109A7 - 200916-A-BT735-939.jpg|thumb|An M992A3 FAASV]]

The M992 field artillery ammunition supply vehicle (FAASV) is built on the chassis of the M109. It replaced the [[M548]]. Unlike the M548, it is armored. This ammunition vehicle has no turret, but has a taller superstructure to store 93 rounds and an equivalent number of powders and primers.

This vehicle is fitted with a [[Halon systems|Halon fire suppression system]] and a weapons mount similar to that on the M109 turret, usually mounting a [[Mk 19 grenade launcher]] for local defense against infantry and light armored vehicles.

The vehicle contains a 2-stroke diesel powered auxiliary power unit that can power all non-automotive energy requirements on the FAASV and on the M109.

===K66===
The K66 was a planned ammunition support vehicle for the K55. As a follow-up to the K55 program, Samsung Aerospace Industries prepared for licensing a local variant of the M992, featuring such modifications as NBC protection and an increase of ammunition storage capacity to 110 rounds, 116 packs of powders, and 132 primers.<ref>{{cite web|url=http://www.jcs.mil.kr/views/jsp/weapon/weapon_read.jsp?id=176&depth1=A&depth2=03&depth3=01|title=K66|url-status=dead|archiveurl=https://web.archive.org/web/20110430092508/http://www.jcs.mil.kr/views/jsp/weapon/weapon_read.jsp?id=176&depth1=A&depth2=03&depth3=01|archivedate=2011-04-30}}</ref>

In 1987, Samsung Aerospace Industries competed against the Daewoo Heavy Industries' ammunition support vehicle based on the [[K200 KIFV|K200 APC]]. Daewoo Heavy Industries' vehicle was selected as the K66, but failed the test evaluation. The K66 project was cancelled in the mid-1990s, resulting in a lawsuit.<ref name="K66"/>

===K77 FDCV (fire direction center vehicle)===
The K77 FDCV is a command & control post vehicle variant based on the K55 platform.<ref>{{Cite web |title=Hanwha Defense K77 |url=https://www.hanwha-defense.co.kr/eng/products/firearms-system-k77.do |access-date=2022-08-08 |website=www.hanwha-defense.co.kr |language=en |archive-date=20 January 2022 |archive-url=https://web.archive.org/web/20220120223739/https://www.hanwha-defense.co.kr/eng/products/firearms-system-k77.do |url-status=dead }}</ref>

===K56 ARV (ammunition resupply vehicle)===
The K56 ARV is an ammunition resupply vehicle based on the K55 platform.<ref>{{Cite web |title=한화디펜스 K56 |url=https://www.hanwha-defense.co.kr/kor/products/firearms-system-k56.do |access-date=2022-08-08 |website=www.hanwha-defense.co.kr |language=ko |archive-date=30 October 2021 |archive-url=https://web.archive.org/web/20211030085647/https://www.hanwha-defense.co.kr/kor/products/firearms-system-k56.do |url-status=dead }}</ref> Unlike the K10 ARV, the K56 can resupply both the K55A1 and the [[K9 Thunder]]. It has a 45.7% (4,197 out of 9,191 total parts) compatibility with the K55A1.<ref name="K56">{{Cite web |title=K55A1자주포의 단짝 K56탄약운반장갑차 실전 배치 |url=https://www.korea.kr/news/pressReleaseView.do?newsId=156437911 |access-date=2022-08-19 |website=www.korea.kr |language=ko}}</ref>

After 10 months of pilot experiment, the K56 program was authorized by the DAPPC (Defense Acquisition Program Promotion Committee) in February 2007.<ref>{{Cite web |title=제13회 방위사업추진위원회 개최 결과 |url=https://n.news.naver.com/mnews/article/234/0000000054?sid=123 |access-date=2022-08-12 |website=[[Naver News]] |language=ko}}</ref> In May 2007, the DAPPC allocated 16 billion KRW for research and development for 2008 to 2010, with plans to produce 520 vehicles between 2011 and 2020.<ref>{{Cite web |title=K-55용 탄약운반 장갑차 3년내 개발 |url=https://n.news.naver.com/mnews/article/001/0001624797?sid=100 |access-date=2022-08-19 |website=[[Naver News]] |language=ko}}</ref> In June 2008, Samsung Techwin was selected as the main contractor for the project.<ref name="K56 audit">{{Cite web |last=송 |first=한진 |title=李 국방, 제28회 방위사업추진위원회 주재 |url=https://n.news.naver.com/mnews/article/003/0002160787?sid=100 |access-date=2022-08-19 |website=[[Naver News]] |language=ko}}</ref> Later, the development completion schedule was delayed to 2011, while the total production amount was increased to 700 vehicles with a cost of 1.3 trillion KRW between 2012 and 2021.<ref>{{Cite web |date=2010-09-27 |title=자주포 탄약운반장갑차 개발, 엉터리 조사 토대로… 軍, 1조2000억원대 사업 강행 |url=https://news.kmib.co.kr/article/view.asp?arcid=0004155324 |access-date=2022-08-19 |website=[[Kukmin Ilbo]] |language=ko}}</ref>

In September 2010, the Board of Audit and Inspection claimed that the [[Republic of Korea Army|Army]] was biased during evaluation, and demanded re-analysis of the project regarding inefficiency of the system. The [[Defense Acquisition Program Administration]] (DAPA) ignored the Board and continued with the project while the Army purposely delayed complying.<ref name="K56 audit"/> In June 2011, the Ministry of Defense again ordered a reexamination of the resupply vehicle.<ref>{{Cite web |date=2011-06-14 |title=軍 중기 전력 13개 사업 재검토 |url=https://news.kmib.co.kr/article/view.asp?arcid=0005058445 |access-date=2022-08-19 |website=[[Kukmin Ilbo]] |language=ko}}</ref> DAPA instead requested a budget for the program, and the development was completed in October 2011.<ref>{{Cite web |last=홍 |first=장기 |title=탱크 여러대 잡는 '확산탄' 2014년 도입 |url=https://n.news.naver.com/mnews/article/086/0002058096?sid=102 |access-date=2022-08-19 |website=[[Naver News]] |language=ko}}</ref><ref name="K56"/> In July 2013, the DAPA announced the 1st production batch of the K56 between 2013 and 2015 for 65 billion KRW.<ref>{{Cite web |title=제 68회 방위사업추진위원회 개최결과 |url=https://www.korea.kr/news/pressReleaseView.do?newsId=155909059 |access-date=2022-08-10 |website=www.korea.kr |language=ko}}</ref>

In December 2015, Hanwha Techwin signed a contract with the DAPA for a 2nd production batch. In January 2018, Hanwha Land Systems announced a 166.4 billion KRW contract with the DAPA for a 3rd production batch and related products.<ref>{{Cite web |last=NEWSIS |date=2018-01-02 |title=한화테크윈 종속사, 방위청과 4729억원 규모 공급 계약 체결 |url=https://www.newsis.com/view/?id=NISX20180102_0000192400 |access-date=2022-08-22 |website=[[Newsis]] |language=ko}}</ref> In June 2020, Hanwha Defense announced 380.3 billion KRW contract with the DAPA for a 4th production batch.<ref>{{Cite web  |date=2020-06-30 |title=한화디펜스, 3803억원 규모 K56 장갑차 4차 양산 계약 |url=https://news.mt.co.kr/mtview.php?no=2020063008480370321 |access-date=2022-08-22 |website=Money Today |language=ko}}</ref> South Korea plans a 5th production batch and to achieve full operational capability by 2025. All K56s were delivered to the western front.<ref>{{Cite web  |title=K56 탄약운반장갑차 |url=https://kookbang.dema.mil.kr/newsWeb/20210322/1/BBSMSTR_000000100160/view.do |access-date=2022-08-22 |website=국방일보 |archive-date=31 January 2023 |archive-url=https://web.archive.org/web/20230131175543/https://kookbang.dema.mil.kr/newsWeb/20210322/1/BBSMSTR_000000100160/view.do |url-status=dead }}</ref>

===Training systems===
The US Army uses the fire support combined arms tactical trainer (FSCATT) in two versions, for initial and sustainment training of the M109A6 and M109A5.<ref>{{cite web|title=Fire Support Combined Arms Tactical Trainer (FS-CATT)|url=http://www.peostri.army.mil/PRODUCTS/FS-CATT/|publisher=US Army|access-date=10 December 2011|url-status=dead|archive-url=https://web.archive.org/web/20111109074435/http://www.peostri.army.mil/PRODUCTS/FS-CATT/|archive-date=9 November 2011}}</ref> The system uses an actual surplus turret and a simulated ammunition system.

The Swiss Army uses a highly advanced KAWEST trainer from Van Halteren Metaal of the Netherlands.{{Citation needed|date=November 2024}}

The Dutch, Belgian, Thai, and Israeli armies have various configurations of the Van Halteren Metaal M109 Howitzer Crew Trainer (HCT).{{Citation needed|date=November 2024}}

The US Army PEO STRI had a program called M109A7 Howitzer Crew Trainer (HCT). The plan was to procure 16 systems beginning in the 3rd Quarter of FY 20.<ref>
{{Cite web |url=https://www.fbo.gov/index?s=opportunity&mode=form&id=bfa37012ddb08eb848b2ee5653f562d3&tab=core&_cview=1 |title=Howitzer Crew Trainer (HCT)- Sources Sought - W900KK-19-C-HCT1 - Federal Business Opportunities: Opportunities |access-date=21 January 2019 |archive-url=https://web.archive.org/web/20190122094642/https://www.fbo.gov/index?s=opportunity&mode=form&id=bfa37012ddb08eb848b2ee5653f562d3&tab=core&_cview=1 |archive-date=22 January 2019 |url-status=live }}
</ref>