Editing Bell Boeing V-22 Osprey (section)

===Propulsion===
[[File:V-22-166480-FAR01.jpg|thumb|Closeup of rotor and engine of a MV-22B |alt=A closeup of an MV-22B's rotor and engine tilted slightly upward.]]

The V-22's two [[Rolls-Royce T406|Rolls-Royce AE 1107C]] engines are connected by [[drive shaft]]s to a common central [[Transmission (mechanics)|gearbox]] so that one engine can power both proprotors if an engine failure occurs.<ref name=Norton_p98-9>Norton 2004, pp. 98–99.</ref> Either engine can power both proprotors through the wing driveshaft.<ref name=v22fly/> However, the V-22 is generally not capable of hovering on one engine.<ref>Whittle, Richard. "[http://breakingdefense.com/2015/07/fatal-crash-prompts-marines-to-change-osprey-flight-rules/ Fatal Crash Prompts Marines To Change Osprey Flight Rules] {{Webarchive|url=https://web.archive.org/web/20150719000019/http://breakingdefense.com/2015/07/fatal-crash-prompts-marines-to-change-osprey-flight-rules/ |date=2015-07-19}}". ''Breaking Defense'', 16 July 2015.</ref> If a proprotor gearbox fails, that proprotor cannot be [[Propeller (aircraft)#Feathering|feathered]], and both engines must be stopped before an [[emergency landing]]. The autorotation characteristics are poor because of the rotors' low [[inertia]].<ref name=v22fly/> The AE 1107C engine has a two-shaft axial design with a 14-stage compressor, an effusion-cooled annular combustor, a two-stage gas generator turbine, and two-stage power turbine.<ref>{{cite web |last=Welt |first=Flying |date=14 May 2023 |title=Bell Boeing V 22 Osprey, the World's First Production Military Tiltrotor Aircraft |url=https://www.flyingwelt.com/2023/05/bell-boeing-v-22-osprey-the-worlds-first-production-military-tiltrotor-aircraft/ |access-date=24 November 2023 |website=Flying Welt |language=en-US |archive-date=24 November 2023 |archive-url=https://web.archive.org/web/20231124051636/https://www.flyingwelt.com/2023/05/bell-boeing-v-22-osprey-the-worlds-first-production-military-tiltrotor-aircraft/ |url-status=live}}</ref>

[[File:V22-Osprey.jpg|thumb|left|V-22 with rotors tilted, condensation trailing from propeller tips]]
In September 2013, Rolls-Royce announced that it had increased the AE-1107C engine's power by 17% via the adoption of a new Block 3 turbine, increased fuel valve flow capacity, and software updates; it should also improve reliability in high-altitude, high-heat conditions and boost maximum payload limitations from {{convert|6000|to|8000|ft|m|abbr=on}}. A Block 4 upgrade is reportedly being examined, which may increase power by up to 26%, producing close to {{convert|10000|shp|kW|abbr=on}}, and improve fuel consumption.<ref>[https://archive.today/20130920190720/http://www.defensenews.com/article/20130916/DEFREG02/309160009/Rolls-Royce-Boosts-Power-V-22-Engines "Rolls-Royce Boosts Power for V-22 Engines"]. Defense News, 16 September 2013.</ref>

In August 2014, the U.S. military issued a [[request for information]] for a potential drop-in replacement for the AE-1107C engines. Submissions must have a power rating of no less than {{convert|6100|shp|kW|abbr=on}} at 15,000&nbsp;rpm, operate at up to {{convert|25000|ft|m|abbr=on}} at up to {{convert|130|F|C|abbr=off}}, and fit into the existing wing nacelles with minimal structural or external modifications.<ref>[http://www.flightglobal.com/news/articles/us-military-seeking-replacement-v-22-engines-403177/ US military seeking replacement V-22 engines] {{Webarchive|url=https://web.archive.org/web/20140907171441/http://www.flightglobal.com/news/articles/us-military-seeking-replacement-v-22-engines-403177/ |date=7 September 2014}} – Flightglobal.com, 29 August 2014</ref> In September 2014, the U.S. Navy, who already purchase engines separately to airframes, was reportedly considering an alternative engine supplier to reduce costs.<ref>Wall, Robert, "US mulls engine options for its Osprey aircraft", ''The Wall Street Journal'', 2 September 2014, p.B3</ref> The [[General Electric GE38]] is one option, giving commonality with the [[Sikorsky CH-53K King Stallion]].<ref>[http://www.flightglobal.com/news/articles/us-navy-developing-early-plans-for-v-22-mid-life-upgrade-411212/ "US Navy developing early plans for V-22 mid-life upgrade"] {{Webarchive|url=https://web.archive.org/web/20150416231330/http://www.flightglobal.com/news/articles/us-navy-developing-early-plans-for-v-22-mid-life-upgrade-411212/ |date=16 April 2015}} – Flightglobal.com, 15 April 2015.</ref>

The V-22 has a maximum rotor [[downwash]] speed of over {{convert|80|kn|mph kph}}, more than the {{convert|64|kn|mph kph|adj=on}} lower limit of a [[hurricane]].<ref name=randwash>John Gordon IV et al. [https://www.rand.org/pubs/documented_briefings/2005/RAND_DB472.pdf Assessment of Navy Heavy-Lift Aircraft Options] p39. ''[[RAND Corporation]]'', 2005. Retrieved 18 March 2012. {{ISBN|0-8330-3791-9}}. [https://web.archive.org/web/20110927172859/https://www.rand.org/pubs/documented_briefings/2005/RAND_DB472.pdf Archived] in 2011.</ref><ref name=NOAA>[https://web.archive.org/web/20080226215213/http://www.srh.noaa.gov/fwd/wcm/hurric.pdf "Hurricanes... Unleashing Nature's Fury: A Preparedness Guide"]. [[National Oceanic and Atmospheric Administration]], [[National Weather Service]], September 2006.</ref> The rotorwash usually prevents the starboard door's usage in hover; the rear ramp is used for rappelling and hoisting instead.<ref name="v22fly">McKinney, Mike. [http://www.verticalmag.com/features/features_article/20112-flying-the-v-22.html "Flying the V-22"] ''[[Vertical (magazine)|Vertical]]'', 28 March 2012. [https://web.archive.org/web/20140430000553/http://www.verticalmag.com/features/features_article/20112-flying-the-v-22.html Archived] on 30 April 2014.</ref><ref name=fastrope>Waters, USMC Cpl. Lana D. [https://web.archive.org/web/20041120010423/http://www.navy.mil/view_single.asp?id=18900 V-22 Osprey Fast rope 1] ''[[United States Marine Corps|USMC]]'', 6 November 2004. [https://web.archive.org/web/20050321095806/http://www.navy.mil/view_single.asp?id=18900 Archived] on 21 March 2005.</ref> The V-22 loses 10% of its vertical lift over a [[tiltwing]] design when operating in helicopter mode because of the wings' airflow resistance, while the tiltrotor design has better short takeoff and landing performance.<ref>Trimble, Stephen. [http://www.flightglobal.com/blogs/the-dewline/2009/06/boeing-looks-ahead-to-a-v-23-o.html "Boeing looks ahead to a 'V-23' Osprey"]. {{Webarchive|url=https://web.archive.org/web/20090625022409/http://www.flightglobal.com/blogs/the-dewline/2009/06/boeing-looks-ahead-to-a-v-23-o.html |date=25 June 2009}} ''Flight Global'', 22 June 2009. [https://web.archive.org/web/20150112022437/http://www.flightglobal.com/blogs/the-dewline/2009/06/boeing-looks-ahead-to-a-v-23-o/ Archived] on 12 January 2015.</ref> V-22s must keep at least {{convert|25|ft|m|abbr=on}} of vertical separation between each other to avoid each other's rotor wake, which causes turbulence and potentially control loss.<ref name=whittle2015-05-15/> The extreme rotor downwash of the V-22 has caused incidents when rappelling or fast roping from the aircraft, including a soldier being blown 3 meters away from his intended dismount point by the force of the downwash.<ref>{{Cite web |last=|date=1996-03-13 |title=Concerns about V-22 downwash crop |url=https://www.flightglobal.com/concerns-about-v-22-downwash-crop/10171.article |access-date=2024-11-03 |website=Flight Global |language=en}}</ref> The downwash is strong enough to destroy unstrengthened helipads and can create flying debris in the landing zone that can injure bystanders or potentially damage the aircraft; an incident involving a Marine Corps Osprey in 2010 resulted in 10 bystanders suffering downwash-related injuries.<ref>{{Cite web |last=Trevithick |first=Joseph |date=2021-04-22 |title=Watch This CV-22 Osprey's Rotor Downwash Absolutely Demolish A Hospital's Helipad |url=https://www.twz.com/40289/watch-this-cv-22-ospreys-rotor-downwash-absolutely-demolish-a-hospitals-helipad |access-date=2024-11-03 |website=The War Zone |language=en-US}}</ref><ref>"Marine aircraft blows tree branches, injures 10 on ground during NYC landing for Fleet Week"  May 31, 2010 Fox News https://www.foxnews.com/us/marine-aircraft-blows-tree-branches-injures-10-on-ground-during-nyc-landing-for-fleet-week</ref>