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63-516: The Boeing Vertol CH-46 Sea Knight is an American medium-lift tandem-rotor transport helicopter powered by twin turboshaft engines . It was designed by Vertol and manufactured by Boeing Vertol following Vertol's acquisition by Boeing . Development of the Sea Knight, which was originally designated by the firm as the Vertol Model 107 , commenced during 1956. It was envisioned as

126-514: A compressor stall , had a lifespan as low as 85 flight hours; on 21 July 1966, all CH-46s were grounded until more efficient filters had been fitted. On 3 May 1967, a CH-46D at Marine Corps Air Facility Santa Ana crashed, killing all four members of the crew. Within three days the accident investigators had determined that the mounting brackets of the main transmission had failed, allowing the front and rear overlapping rotors to intermesh. All CH-46s were temporarily grounded for inspection. On 13 May,

189-423: A CH-46A crashed off the coast of Vietnam when the tail pylon containing the engines, main transmission and aft rotors broke off in flight. All four crew members were killed. On 20 June, another CH-46A crashed, though two of the four-man crew survived. Once again, even though the aircraft was not recovered from the water, failure of some sort in the rear pylon was suspected. On 30 June a CH-46D at Santa Ana crashed when

252-414: A crew of three; a larger crew could be accommodated when required, which would be dependent upon mission specifics. For example, a search and rescue (SAR) variant would usually carry a crew of five (Pilot, Co-Pilot, Crew Chief, Swimmer, and Medic) to facilitate all aspects of such operations. For self-defense, a pintle -mounted 0.50 in (12.7 mm) Browning machine gun could be mounted on each side of

315-593: A downed AH-1 Cobra, and then carried infantry from the 75th Ranger Regiment to secure and evacuate U.S. students at the Grand Anse campus of St. George's University , though one crashed after colliding with a palm tree. CH-46E Sea Knights were also used by the U.S. Marine Corps during the 2003 invasion of Iraq . In one incident on 1 April 2003, Marine CH-46Es and CH-53Es carried U.S. Army Rangers and Special Operations troops on an extraction mission for captured Army Private Jessica Lynch from an Iraqi hospital. During

378-425: A fixed tricycle landing gear , complete with twin wheels on all three legs of the landing gear; this configuration results in a nose-up stance, helping to facilitate cargo loading and unloading. Two of the main landing gear were installed within protruding rear sponsons ; the free interior space of the sponsons are also used to house fuel tanks, possessing a total capacity of 350 US gallons (1,438 L). The interior of

441-455: A mechanism to neutralize the yawing movement produced by the single large rotor. This is commonly accomplished by a tail rotor , coaxial rotors , and the NOTAR systems. Tandem-rotor helicopters, however, use counter-rotating rotors , with each cancelling out the other's torque . Therefore, all of the power from the engines can be used for lift , whereas a single-rotor helicopter uses some of

504-459: A nose-mounted weather radar, a tail-mounted auxiliary power unit, a new high-speed rescue hoist mounted over the side door and front-mounted searchlights. A total of six CH-113s and five CH-113As were upgraded with the last delivered in 1984. Nonetheless, as a search and rescue helicopter it endured heavy use and hostile weather conditions; which had begun to take their toll on the Labrador fleet by

567-571: A prototype, powered by a pair of Lycoming T53 turboshaft engines, each one being capable of producing 877 shp (640 kW), commenced. On 22 April 1958, the V-107 prototype performed its maiden flight . In order to garner publicity for the newly developed rotorcraft, it was decided to use the prototype to conduct a series of publicised flight demonstrations during a tour across the United States and several overseas nations. During June 1958, it

630-636: A rotor blade separated from the aircraft, all three of the crew survived. As a result of this latest accident, all CH-46Ds were immediately grounded, but the CH-46As continued flying. On 3 July another CH-46A crashed in Vietnam, killing all four Marines of its crew. The cause of the crash again was traced to failure of the main transmission. On 31 August 1967, a CH-46A on a medical evacuation mission to USS  Tripoli disintegrated in midair killing all its occupants. The following day another CH-46A experienced

693-482: A similar incident at Marble Mountain Air Facility leading to the type being grounded for all except emergency situations and cutting Marine airlift capacity in half. An investigation conducted by a joint Naval Air Systems Command/Boeing Vertol accident investigation team revealed that structural failures were occurring in the area of the rear pylon resulting in the rear rotor tearing off in flight and may have been

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756-620: A successor to the first generation of rotorcraft, such as the H-21 "Flying Banana", that had been powered by piston engines ; in its place, the V-107 made use of the emergent turboshaft engine. On 22 April 1958, the V-107 prototype performed its maiden flight . During June 1958, the US Army awarded a contract for the construction of ten production-standard aircraft, designated as the YHC-1A , based on

819-406: A total of 15 Labradors were ultimately in service. The Labrador was fitted with a watertight hull for marine landings, a 5,000 kilogram cargo hook and an external rescue hoist mounted over the right front door. It featured a 1,110 kilometer flying range, emergency medical equipment and an 18-person passenger capacity. In multiple instances throughout the 1970s and 1980s, this increased range provided

882-417: A transmission that ensures the rotors are synchronized and do not hit each other, even during an engine failure. Tandem-rotor designs achieve yaw by applying opposite left and right cyclic to each rotor, effectively pulling both ends of the helicopter in opposite directions. To achieve pitch , opposite collective is applied to each rotor; decreasing the lift produced at one end, while increasing lift at

945-487: The Federal Aviation Administration (FAA). Plans for actual production of the aircraft were not announced. The Boeing Vertol CH-46 Sea Knight is a medium-lift tandem-rotor transport helicopter , furnished with a set of counter-rotating main rotors in a tandem-rotor configuration. It was typically powered by a pair of General Electric T58 turboshaft engines, which were mounted on each side of

1008-715: The Marine Corps Development and Education Command obtained several CH-46s to perform herbicide dissemination tests using HIDAL (Helicopter, Insecticide Dispersal Apparatus, Liquid) systems; testing indicated the need for redesign and further study. Tandem-rotor helicopters were often used to transport nuclear warheads; the CH-46A was evaluated to deploy Naval Special Forces with the Special Atomic Demolition Munition (SADM). Nuclear Weapon Accident Exercise 1983 (NUWAX-83), simulating

1071-416: The U.S. Marine Corps evolved a requirement for a medium-lift, twin-turbine troop/cargo assault helicopter to replace the various piston-engined types that were then in widespread use with the service. That same year, American aviation company Boeing acquired Vertol, after which the group was consequently renamed Boeing Vertol . Following a competition between several competing designs, during early 1961, it

1134-621: The US Navy 's standard medium-lift utility helicopter prior to the type being phased out of service in favor of the MH-60S Knighthawk during the early 2000s. Several overseas operators acquired the rotorcraft as well. Canada operated the Sea Knight, designated as CH-113 ; the type was used predominantly in the SAR role until 2004. Other export customers for the type included Japan , Sweden , and Saudi Arabia . The commercial version of

1197-620: The 1972 Easter Offensive , Sea Knights saw heavy use to convey US and South Vietnamese ground forces to and around the front lines. Marine CH-46s participated in Operation Frequent Wind , the evacuation of Saigon , in April 1975 and the last helicopter to leave the roof of the US embassy was a CH-46 of HMM-164 . By the end of US military operations in Vietnam, over a hundred Sea Knights had been lost to enemy fire. In February 1968

1260-615: The 1990s, resulting in increasing maintenance costs and the need for prompt replacement. In 1992, it was announced that the Labradors were to be replaced by 15 new helicopters, a variant of the AgustaWestland EH101 , designated CH-149 Chimo . The order was subsequently cancelled by the Jean Chrétien Liberal government in 1993, resulting in cancellation penalties, as well as extending the service life of

1323-688: The Air Wing in late 2014. In Afghanistan the CH-46s were used by Embassy Air for secure transport of State Department personnel. The CH-46s were equipped with missile warning sensors and flare dispensers and could be armed with M240D or M2 Browning machine guns. A report in September 2019 by the State Department Inspector General found that a seat on a CH-46 for a seven-minute flight cost US$ 1,500 (~$ 1,763 in 2023). Seven of

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1386-471: The CH-46 was largely taken up by its cargo bay, complete with a rear loading ramp that could be removed or left open in flight for the carriage of extended cargoes or for parachute drops. Various furnishings were normally provided to aid in its use as a utility rotorcraft, such as an internal winch mounted within the forward cabin, which can be used to assisting loading by pulling external cargo on pallets into

1449-472: The CH-46 was one of the prime US Marine troop transport helicopters in the theater, slotting between the smaller Bell UH-1 Iroquois and larger Sikorsky CH-53 Sea Stallion and progressively replacing the UH-34 . CH-46 operations were plagued by major technical problems; the engines, being prone to foreign object damage (FOD) from debris being ingested when hovering close to the ground and subsequently suffering

1512-816: The CH-46 was retired by the Marine Medium Helicopter Training Squadron 164 , the last Marine Corps squadron to transition to the MV-22. The USMC retired the CH-46 on 1 August 2015 in a ceremony at the Udvar-Hazy Center near Washington DC. Beginning in April 2011 the Navy's Fleet Readiness Center East began refurbishing retired USMC CH-46Es for service with the United States Department of State Air Wing . A number of CH-46s from HMX-1 were transferred to

1575-522: The CH-46D standard. Between 1968 and 1971, the U.S. Marine Corps received a number of CH-46F standard rotorcraft. This model retained the T58-GE-10 engines used on the CH-46D while featuring revised avionics and featured a number of other modifications. The CH-46F was the final production model of the type. During its service life, the Sea Knight received a variety of upgrades and modifications. Over time,

1638-633: The CH-46D to carry an increased payload, such as up to 25 troops or a maximum of 7,000 pounds (3,180 kg) of cargo. During late 1967, the improved model was introduced to the Vietnam theater , where it supplemented the U.S. Marine Corps' existing CH-46A fleet, which had proven to be relatively unreliable and problematic in service. Along with the USMC's CH-46Ds, the U.S. Navy also acquired a small number of UH-46Ds for ship resupply purposes. In addition, approximately 33 CH-46As were progressively re-manufactured to

1701-512: The Labrador fleet. However, in 1998, a CH-113 from CFB Greenwood crashed on Quebec's Gaspé Peninsula while returning from a SAR mission, resulting in the deaths of all crewmembers on board. The crash placed pressure upon the government to procure a replacement, thus an order was placed with the manufacturers of the EH101 for 15 aircraft to perform the search-and-rescue mission, designated CH-149 Cormorant . CH-149 deliveries began in 2003, allowing

1764-640: The SAR role and the Canadian Army acquired 12 of the similar CH-113A Voyageur for the medium-lift transport role. The RCAF Labradors were delivered first with the first one entering service on 11 October 1963. When the larger CH-147 Chinook was procured by the Canadian Forces in the mid-1970s, the Voyageur fleet was converted to Labrador specifications to undertake SAR missions. The refurbished Voyageurs were re-designated as CH-113A Labradors, thus

1827-440: The Sea Knight to carry up to 17 passengers or a maximum of 4,000 pounds (1,815 kg) of cargo. During 1966, production of the improved CH-46D commenced with deliveries following shortly thereafter. This model featured various improvements, including modified rotor blades and the adoption of more powerful T58-GE-10 turboshaft engines, rated at 1,400 shp (1,040 kW) each. The increased power of these new engines allowed

1890-598: The State Department Air Wing CH-46s took part in the 2021 Kabul Airlift . Prior to the complete withdrawal of U.S. forces, all seven were rendered unusable and abandoned at Kabul International Airport and are seen in many videos and pictures online. One of the CH-46s that was abandoned (BuNo 154038, c/n 2389) also took part in Operation Frequent Wind 46 years earlier. The U.S. State Department drew criticism for leaving behind

1953-527: The USA. Data from The International Directory of Military Aircraft, 2002/2003, The Complete Encyclopedia of World Aircraft : Boeing Vertol Model 107 (H-46 Sea Knight), Encyclopedia of world military aircraft : Volume One General characteristics Performance Armament Related development Aircraft of comparable role, configuration, and era Related lists [REDACTED] Tandem rotors Single-rotor helicopters need

Boeing Vertol CH-46 Sea Knight - Misplaced Pages Continue

2016-469: The V-107; this initial order was later cut down to three YHC-1As. During 1961, the US Marine Corps (USMC), which had been studying its requirements for a medium-lift, twin-turbine cargo/troop assault helicopter, selected Boeing Vertol's Model 107M as the basis from which to manufacture a suitable rotorcraft to meet their needs. Known colloquially as the "Phrog" and formally as the "Sea Knight", it

2079-471: The Vietnam War and its retirement in 2015. The type's longevity and reputation for reliability led to mantras such as "phrogs phorever" and "never trust a helicopter under 30". CH-46s transported personnel, evacuated wounded, supplied forward arming and refueling points (FARP), performed vertical replenishment, search and rescue, recovered downed aircraft and crews and other tasks. During the Vietnam War,

2142-428: The aircraft via the ramp and rollers, and an optionally-attached belly-mounted cargo hook , which would be usually rated at 10,000 lb (4,500 kg) for carrying cargoes externally underneath the Sea Knight; despite the hook having been rated at 10,000 lb (4,500 kg), this was safety restricted to less payload as they got older. When operated in a typical configuration, the CH-46 would usually be operated by

2205-400: The aircraft. Commenting on the issue, the U.S. State Department claimed that the helicopters were already being phased out of State Department Air Wing due to their age and the inability to support them. The seven CH-46s left behind were the only U.S. State Department aircraft left behind at Kabul International Airport. The Royal Canadian Air Force procured six CH-113 Labrador helicopters for

2268-623: The capability of the CH-113 to provide assistance to U.S. Coast Guard (USCG) missions or perform long range medevacs over distances the USCG helicopters at the time simply could not reach. In 1981, a mid-life upgrade of the fleet was carried out by Boeing Canada in Arnprior, Ontario . Known as the SAR-CUP (Search and Rescue Capability Upgrade Program), the refit scheme included new instrumentation,

2331-595: The cause of several earlier losses. The team recommended structural and systems modifications to reinforce the rear rotor mount as well as installation of an indicator to detect excessive strain on critical parts of the aircraft. 80 CH-46As were shipped to Marine Corps Air Station Futenma , Okinawa where they received the necessary modifications by a combined force of Marine and Boeing Vertol personnel. The modified CH-46As began returning to service in December 1967 and all had been returned to service by February 1968. During

2394-468: The crash of a Navy CH-46E carrying 3 nuclear warheads, was conducted at the Nevada Test Site on behalf of several federal agencies; the exercise, which used real radiological agents, was depicted in a Defense Nuclear Agency -produced documentary. U.S. Marine CH-46s were used to deploy the 8th Marine Regiment into Grenada during Operation Urgent Fury , evacuated the surviving crewmember of

2457-784: The diversity of tasks was commuter service in the mid-1960s from the roof of the Pan Am skyscraper in Manhattan to JFK Airport in Queens, pulling a hover barge , and constructing transmission towers for overhead power lines . In December 2006, Columbia Helicopters purchased the type certificate of the Model 107 from Boeing, with the aim of eventually producing new-build aircraft themselves. [REDACTED]   Thailand A variety of CH-46 are on display at museums in Canada, Japan, Sweden, and

2520-444: The engine power to counter the torque. An alternative is to mount two rotors in a coaxial configuration. The first successful tandem-rotor helicopter was built by Nicolas Florine in 1927. Advantages of the tandem rotor system are a larger center of gravity range and good longitudinal stability . Disadvantages of the tandem rotor system are a complex transmission and the need for two large rotors. The two rotors are linked by

2583-399: The first MV-22 squadron. The replacement process continued through the other medium helicopter squadrons into 2014. On 5 October 2014, the Sea Knight performed its final service flight with the U.S. Marine Corps at Marine Corps Air Station Miramar . HMM-364 was the last squadron to use it outside the United States, landing it aboard USS  America on her maiden transit. On 9 April 2015,

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2646-862: The first turbine engine to gain FAA certification for civil helicopter use. The engine was license-built and further developed by de Havilland in the UK as the Gnome , in the West Germany by Klöckner-Humboldt-Deutz , and also manufactured by Alfa Romeo and the IHI Corporation . Development commenced with a 1953 US Navy requirement for a helicopter turboshaft to weigh under 400 lb (180 kg) while delivering 800 hp (600 kW). The engine General Electric eventually built weighed only 250 lb (110 kg) and delivered 1,050 hp (780 kW) and

2709-471: The helicopter. Service in southeast Asia resulted in the addition of armor along with the machine guns. The CH-46 was a partially amphibious helicopter , and could land directly on water and rest for up to two hours in calm water. The rear sponsons hold two of the three landing gear units as well as self-sealing fuel tanks. Known colloquially as the "Phrog", the Sea Knight was used in all U.S. Marine operational environments between its introduction during

2772-582: The last CH-113 to be retired in 2004. In October 2005 Columbia Helicopters of Aurora, Oregon purchased eight of the retired CH-113 Labradors to add to their fleet of 15 Vertol 107-II helicopters. In 1963, Sweden procured ten UH-46Bs from the US as a transport and anti-submarine helicopter for the Swedish Armed Forces , designated Hkp 4A. In 1973, a further eight Kawasaki-built KV-107s, which were accordingly designated Hkp 4B, were acquired to replace

2835-588: The later Kawasaki-built Sea Knights continued in operational service until 2011, they were replaced by the UH-60 Black Hawk and NH90 . On 15 September 2023, Argentina 's Air Force chief Gen. Xavier Issac briefed the media that Argentina had sent a letter requesting the US to approve the refurbishment of surplus CH-46s currently stored with the 309th Aerospace Maintenance and Regeneration Group in Arizona . The availability of civilian-operated CH-46s

2898-722: The loss of numerous US helicopters in the Iraqi theatre, the Marines opted to equip their CH-46s with more advanced anti-missile countermeasures. The U.S. Navy retired the type on 24 September 2004, replacing it with the MH-60S Seahawk ; the Marine Corps maintained its fleet as the MV-22 Osprey was fielded. In March 2006 Marine Medium Helicopter Squadron 263 (HMM-263) was deactivated and redesignated VMM-263 to serve as

2961-407: The majority of the U.S. Marine Corps' Sea Knights were upgraded to the improved CH-46E standard. This model featured fiberglass rotor blades, reinforcement measures throughout the airframe, along with the refitting of further uprated T58-GE-16 engines, capable of producing 1,870 shp (1,390 kW) each; in addition, several CH-46Es were modified to double their maximum fuel capacity. Starting in

3024-568: The manufacturing rights of the 107 to Japanese conglomerate Kawasaki Heavy Industries . Under this arrangement, all Model 107 civilian and military aircraft built in Japan were referred to by the KV 107 designation. On 15 December 2006, Columbia Helicopters, Inc acquired the type certificate for the BV 107-II; at the time, the company was reportedly in the process of acquiring a Production Certificate from

3087-536: The mid-1990s, the Dynamic Component Upgrade (DCU) programmes was enacted, focusing on the implementation of strengthened drive systems and modified rotor controls. The commercial variant, the BV 107-II , was first ordered by New York Airways during 1960. During July 1962, they took delivery of their first three aircraft, which was configured to seat up to 25 passengers. During 1965, Boeing Vertol sold

3150-716: The older Piasecki H-21. During the Cold War, the fleet's primary missions were anti-submarine warfare and troop transportation. They were also frequently employed in the search and rescue role, most famously during the rescue operation of the MS Estonia after it sank in the Baltic Sea on 28 September 1994. In the 1980s, the Hkp 4A was phased out, having been replaced by the Eurocopter AS332 Super Puma ;

3213-415: The opposite end, effectively tilting the helicopter forward or back. Tandem-rotor helicopters have the advantage of being able to hold more weight with shorter blades, since there are two sets. However, the rear rotor works in the aerodynamic shadow of the front rotor, which reduces its efficiency. This loss can be minimized by increasing the distance between the two rotor hubs, and by elevating one hub over

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3276-579: The other. Tandem-rotor helicopters tend to have a lower disk loading than single-rotor helicopters. Tandem-rotor helicopters typically require less power to hover and achieve low-speed flight as compared to single-rotor helicopters. Both configurations typically require the same power to achieve high-speed flight. General Electric T58 The General Electric T58 is an American turboshaft engine developed for helicopter use. First run in 1955, it remained in production until 1984, by which time some 6,300 units had been built. On July 1, 1959, it became

3339-436: The rear rotor pedestal; power to the forward rotor was transferred from the rear-mounted engines via a drive shaft . For redundancy, both engines are coupled so that either one would be capable of powering both of the main rotors in the event of a single engine failure or a similar emergency situation. Each of the rotors feature three blades, which can be folded to better facilitate storage and naval operations. The CH-46 features

3402-535: The rival Sikorsky S-61R in its place. Following the Sea Knight's first flight in August 1962, the military designation was changed to CH-46A . During November 1964, the introduction of the Marines' CH-46A and the Navy's UH-46As commenced. The UH-46A variant was a modified version of the rotorcraft to perform the vertical replenishment mission. The CH-46A was equipped with a pair of T58-GE8-8B turboshaft engines, each being rated at 1,250 shp (930 kW); these allowed

3465-493: The rotorcraft is the BV 107-II , commonly referred to simply as the "Vertol". The Sea Knight is an amphibious helicopter, able to land directly on calm water and float, but only for a few hours. During the 1940s and 1950s, American rotorcraft manufacturer Piasecki Helicopter emerged as a pioneering developer of tandem-rotor helicopters; perhaps the most famous of these being the piston-powered H-21 "Flying Banana", an early utility and transport helicopter. During 1955, Piasecki

3528-507: The subsequent occupation of Iraq and counter-insurgency operations, the CH-46E was heavily used in the CASEVAC role, being required to maintain 24/7 availability regardless of conditions. According to authors Williamson Murray and Robert H Scales, the Sea Knight displayed serious reliability and maintenance problems during its deployment to Iraq, as well as "limited lift capabilities". Following

3591-415: Was also a turbine-powered tandem rotor design but substantially larger than the V-107. All of the U.S. Army's three YHC-1As were powered by pairs of GE-T-58 engines. During August 1959, the first YHC-1A-model rotorcraft conducted its first flight; independently, it was shortly followed by the maiden flight of an improved model intended for the commercial and export markets, designated 107-II . During 1960,

3654-541: Was also being explored. They would be used to support Argentina's Antarctic bases . The CH-46s would replace two Mil Mi-171E helicopters acquired in 2010, but now not able to be repaired by Russia due to sanctions from the Russian invasion of Ukraine . The civilian version, designated as the BV 107-II Vertol , was developed prior to the military CH-46. It was operated commercially by New York Airways, Pan American World Airways and later on by Columbia Helicopters. Among

3717-456: Was announced that Boeing Vertol had been selected to manufacture its model 107M for the U.S. Marine Corps, where it was designated HRB-1 . During 1962, the U.S. Air Force placed its own order for 12 XCH-46B Sea Knight helicopters, which used the XH-49A designation; however, the service later decided to cancel the order due to delays in its delivery; instead, the U.S. Air Force opted to procure

3780-427: Was announced that the U.S. Army had awarded a contract to Vertol for the construction of ten production-standard aircraft based on the V-107, which were designated YHC-1A . However, this order was later decreased to three helicopters; according to aviation author Jay P. Spenser, the cutback had been enacted in order that the U.S. Army would be able to divert funds for the development of the rival V-114 helicopter, which

3843-488: Was officially renamed as Vertol Corporation (standing for vertical take-off and landing ); it was around this time that work commenced on the development of a new generation of tandem rotor helicopter. During 1956, the new design received the internal company designation of Vertol Model 107 , or simply V-107 ; this rotorcraft differed from its predecessors by harnessing the newly developed turboshaft engine instead of piston-based counterparts. During that year, construction of

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3906-611: Was operated across all US Marine Corps' operational environments between its introduction during the Vietnam War and its frontline retirement during 2014. The Sea Knight was operated by the USMC to provide all-weather, day-or-night assault transport of combat troops, supplies and equipment until it was replaced by the MV-22 Osprey during the 2010s. The USMC also used the helicopter for combat support , search and rescue (SAR), casualty evacuation and Tactical Recovery of Aircraft and Personnel (TRAP). The Sea Knight also functioned as

3969-692: Was soon ordered into production. First flight was on a modified Sikorsky HSS-1 in 1957, and civil certification for the CT58-100 variant was obtained two years later. A number of unusual features are incorporated into the T58: The main production version of the engine was the T58-GE-10 , developing 1,400 hp (1,044 kW). The most powerful version, the T58-GE-16, produces 1,870 hp (1,390 kW). Two T58s, converted to turbojets by

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