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CH-46 Sea Knight

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CH-46 Sea Knight
CH-46 Sea Knight
Role Cargo helicopter
Manufacturer Vertol Aircraft Corp.
Boeing Vertol
First flight August 1962
Introduction 1964
Retired 2004-09-04 (USN)
Planned 2014 (USMC)
Status Active service
Primary users United States Marine Corps
Saudi Arabia
Produced 1962–1971
Number built H-46: 524[1]
Unit cost US$6 million in 1987[2]
Variants CH-113 Labrador

The Boeing CH-46 Sea Knight is a medium-lift tandem rotor transport helicopter, used by the United States Marine Corps (USMC) to provide all-weather, day-or-night assault transport of combat troops, supplies and equipment. Assault Support is its primary function, and the movement of supplies and equipment is secondary. Additional tasks include combat support, search and rescue, support for forward refueling and rearming points, CASEVAC and Tactical Recovery of Aircraft and Personnel (TRAP). The commercial version is the BV 107-II, commonly referred to as simply the "Vertol".


Piasecki was a pioneering developer of tandem-rotor helicopters, with the most famous previous helicopter being the H-21 "Flying Banana". Piasecki's former company Vertol began work on a new tandem rotor helicopter designated the Vertol Model 107 or V-107 in 1957. The V-107 had two Lycoming T53 turboshaft engines, producing 860 shp (640 kW) each. The first flight of the V-107 took place on April 22, 1958. The V-107 was then put through a flight demonstration tour in the US and overseas. In June 1958, the US Army awarded a contract to Vertol for ten production aircraft designated "YHC-1A".

A door gunner manning a pintle-mounted .50-caliber machine gun aboard a USMC CH-46.
A door gunner manning a pintle-mounted .50-caliber machine gun aboard a USMC CH-46.

The order was later decreased to three, so the Army could divert funds to the V-114, also a turbine powered tandem, but larger than the V-107. The Army's three YHC-1As were powered by GE-T-58 engines. The YHC-1As first flew in August 1959, and were followed by an improved commercial/export model, the 107-II. During 1960, the U.S. Marine Corps (USMC) evolved a requirement for a twin-turbine troop/cargo assault helicopter to replace the piston engine types then in use. Following a design competition, Boeing Vertol was selected to build its model 107M as the HRB-1, early in 1961. Boeing had acquired Vertol in 1960 and renamed the group Boeing Vertol.

The helicopter was first procured in 1961 to meet the medium-lift requirements of the Marine Corps. Its first flight in August 1962 was followed by a change in designation to CH-46A. Fleet introduction of CH-46As with the Marines and the Navy's UH-46As in November 1964. The UH-46A variant was modified for use in the vertical replenishment role. The CH-46A was equipped with a pair of T58-GE8-8B turboshaft engines rated at 1,250 shp (930 kW) each and could carry 17 passengers or 4,000 pounds (1,815 kg) of cargo. The USMC received 160 CH-46As and the US Navy acquired 14 UH-46As.

US Marines from the 24th MEU prepare to board a CH-46.
US Marines from the 24th MEU prepare to board a CH-46.

Production of the improved CH-46D followed with deliveries beginning in 1966. Its improvements included modified rotor blades and more powerful T58-GE-10 turboshaft engines rated at 1,400 shp (1,040 kW) each. The increased power allowed the D-model to carry 25 troop or 7,000 pounds (3,180 kg) of cargo. A total of 265 CH-46Ds were produced. The Navy received 10 UH-46Ds for ship resupply. Also, approximately 12 CH-46As were upgraded to CH-46Ds.

The Marines also received 174 CH-46Fs from 1968 to 1971. The F-model retained the D-model's T58-GE-10 engines but revised the avionics and included other modifications. The CH-46F was the final production model with the last helicopter being the 524th H-46 produced. The Sea Knight has undergone upgrades and modifications. Most USMC Sea Knights were upgraded to CH-46E standard. The CH-46E features fiberglass rotor blades, airframe reinforcement, and further uprated T58-GE-16 engines producing 1,870 shp (1,390 kW) each. Some CH-46Es have been given doubled fuel capacity. The Dynamic Component Upgrade (DCU) incorporated starting in the mid-1990s provides for increased capabilities through strengthened drive systems and rotor controls.

The commercial variant, the BV 107-II, was first ordered by New York Airways in 1960. They took delivery of their first three aircraft, configured for 25 passengers, in July 1962.

In 1965, Boeing Vertol sold the manufacturing rights of the 107 to Kawasaki Heavy Industries. Under this arrangement, all Model 107 civilian and military aircraft built in Japan are known as KV 107.

On December 15, 2006, Columbia Helicopters, Inc acquired the type certificate for the Boeing Vertol 107-II, and is in the process of acquiring a Production Certificate from the FAA. Plans for actual production of the aircraft have not been announced.


The CH-46 has tandem contrarotating rotors that were powered by two GE T58 turboshaft engines. The engines are mounted on each side of the rear rotor pedestal with a driveshaft to the forward rotor. The engines are coupled so either could power both rotors in an emergency. The rotors feature three blades and could be folded for on-ship operations.

The CH-46 has a cargo bay with a rear loading ramp that could be removed or left open in flight for extended cargo or for parachute drops. A belly sling hook could be attached for carrying external cargo. It has a crew of three. A pintle-mounted 0.50 in (12.7 mm) Browning machine gun was mounted on each side of the helicopter for self-defense. Service in southeast Asia resulted in the addition of armor with the guns.

The CH-46 has fixed tricycle landing gear, with twin wheels on all three units. The gear configuration causes a nose-up stance to facilitate cargo loading and unloading. The main gear are fitted in rear sponsons that also contained fuel tanks with a total capacity of 350 US gallons (1,438 L).

Operational history



Known colloquially as the "Phrog", and used in all Marine combat and peacetime environments since its introduction. Still regularly flown by the Marine Corps, its longevity as a reliable airframe has led to such mantras as "phrogs phorever" and "never trust a helicopter under 30".

CH-46E Sea Knights were used by the USMC during its 2003 invasion of Iraq. CH-46Es transported personnel, brought supplies to forward arming and refueling points (FARP), carried ammunition and various tasks. Marine CH-46Es and CH-53Es carried US Army Rangers and Special Operations troops in a mission to extract captured Army Private Jessica Lynch from an Iraqi hospital on 1 April 2003.

While the United States Navy retired the airframe on September 24, 2004, replacing it with the MH-60S Knighthawk, the Marine Corps plans to maintain its fleet until the MV-22 is fully fielded. In March 2006 Marine Medium Helicopter Squadron 263 (HMM-263) was deactivated and redesignated VMM-263 to serve as the first MV-22 squadron. The replacement process is expected to continue through the other medium helicopter squadrons into 2014.


Columbia Helicopters BV 107-II
Columbia Helicopters BV 107-II

The Civilian version, the BV 107-II Vertol was developed prior to the military CH-46, and was operated commercially by New York Airways, Pan American World Airways and currently solely by Columbia Helicopters. As of December 15, 2006 Columbia Helicopters has purchased the Type certificate of the Model 107 from Boeing. Currently the company is seeking FAA issuance of a Production Certificate to produce parts with eventual issuance of a PC to produce aircraft.


US versions

Taken at the West 30th Street Heliport, New York Airways N6676D is hooked to a Ford Mustang for publicity stunt. The Mustang was flown around Manhattan by the BV 107-II.
Taken at the West 30th Street Heliport, New York Airways N6676D is hooked to a Ford Mustang for publicity stunt. The Mustang was flown around Manhattan by the BV 107-II.

Marines load a simulated casualty onto a CH-46E while conducting convoy operations training at Camp Dawson, West Virginia.
Marines load a simulated casualty onto a CH-46E while conducting convoy operations training at Camp Dawson, West Virginia.

A UH-46D lowers mail to the fantail of USS Decatur.
A UH-46D lowers mail to the fantail of USS Decatur.

Boeing Model 360
Boeing Model 360

Total U.S. H-46 production amounted to 525, ending in 1971.

Model 107 
Company model number for basic prototype, 1 built.
Model 107-II 
Commercial airline helicopter. All subsequent commercial aircraft were produced as BV 107-II-2, 2 built as Boeing Vertol prototypes, 5 sold to New York Airways, 10 supplied to Kawasaki as sub-assemblies or as parts.
Model 107M 
Company model number for military transport of BV-107/II-2 for the United States Marine Corps.
Vertol Model 107 for test and evaluation by the United States Army. Adopted by the United States Marine Corps as the HRB-1. Later redesignated YCH-46C, 3 built.
Five Model 114s that that later became the CH-47A Chinook.
Original designation before being renamed as CH-46A before delivery under the 1962 United States Tri-Service aircraft designation system
Assault, utility medium transport and SAR helicopter for the USMC, fitted with two 935-kW (1,250-shp) General Electric T58-GE-8 turboshaft engines. (Previously HRB-1). 160 built for USMC, 1 static airframe.
Utility medium transport helicopter for the United States Navy. Similar to the CH-46A. 14 built.
Approximately 50 CH-46As were converted into SAR helicopters for the United States Navy base rescue role.
Planned conversion of CH-46As into minesweeping helicopters for the US Navy, none converted. Nine SH-3As were converted to the RH-3A configuration instead.
Development of the CH-46A to specification HX/H2 for the United States Air Force; 12 ordered in 1962, cancelled and Sikorsky S-61R / CH-3C ordered instead.
YHC-1A redesignated in 1962. United States Army retained 2, NASA used 1 for vertical autonomous landing trials (VALT).
Assault and utility medium transport helicopter for the USMC, fitted with two 1044-kW (1,400-shp) General Electric T58-GE-10 turboshaft engines. 266 built.
Surviving HH-46A were upgraded and a small number of UH-46Ds were converted into SAR helicopters.
Utility transport helicopter for the US Navy combat supply role. Similar to the CH-46D. 10 built and one conversion from CH-46D.
Approximately 275 -A, -D, and -F airframes were updated to CH-46E standards with improved avionics, hydraulics, drive train and upgraded T58-GE-16 engines.
Three CH-46Es were converted into SAR helicopters for Marine Transport Squadron One (VMR-1) at MCAS Cherry Point.
Improved version of CH-46D, electrical distribution, com/nav update BUNO 154845-157726. Last production model in the United States. 174 built.
Unofficial designation of standard CH-46F used by HMX-1 as VIP support transport helicopter.
Also known as the Boeing Model 360, this Advance Technology Demonstrator from the 1980s never entered production. The aircraft relied heavily on composites for its construction and had a beefier drive train to handle the twin Avco-Lycoming AL5512 engines (4200shp).

Canadian versions

CH-113 Labrador 
Search and rescue version of the Model 107-II-9 for the Royal Canadian Air Force. 6 built.
CH-113A Voyageur 
Assault and utility transport version of the Model 107-II-28 for the Canadian Army. 12 built. Later converted to CH-113A Labrador when the Canadian Forces acquired the CH-147 Chinook.

Swedish Versions

Hkp 4A 
Boeing Vertol 107-II-14, used originally by Air Force for SAR, 10 built.
Hkp 4B 
Boeing Vertol 107-II-15, mine-layer/ASW/SAR helo for Navy, 3 built and 1 conversion from Boeing-Vertol civil prototype.
Kawasaki KV-107-II-16, advanced mine-layer/ASW/SAR helo for Navy, 8 built.
Rebuilt Hkp 4A for Navy as SAR/ASW helo, 4 conversions.

Japanese versions

Columbia Helicopters' Kawasaki Vertol KV-107II at Fox Field
Columbia Helicopters' Kawasaki Vertol KV-107II at Fox Field

A KV-107II from the film You Only Live Twice dropping the bad guys in Tokyo Bay.
A KV-107II from the film You Only Live Twice dropping the bad guys in Tokyo Bay.
KV-107II-1 (CT58-110-1)
Utility transport version, 1 built from Boeing supplied kits.
KV-107II-2 (CT58-110-1)
Commercial airline version, 9 built from Boeing supplied kits.
KV-107IIA-2 (CT58-140-1)
Improved version of the KV-107/II-2, 3 built.
KV-107II-3 (CT58-110-1)
Minesweeping version for the JMSDF, 2 built.
KV-107IIA-3 (CT58-IHI-10-M1)
Uprated version of the KV-107/II-3, 7 built.
KV-107II-4 (CT58-IHI-110-1)
Assault and utility transport version for the JGSDF, 41 built.
KV-107II-4A (CT58-IHI-110-1)
VIP version of the KV-107/II-4, 1 built.
KV-107IIA-4 (CT58-IHI-140-1)
Uprated version of the KV-107/II-4, 18 built.
KV-107II-5 (CT58-IHI-110-1)
Long-range SAR version for the JASDF, 17 built.
KV-107IIA-5 (CT58-IHI-104-1)
Uprated version of the KV-107II-5, 35 built.
KV-107II-7 (CT58-110-1)
VIP transport version, 1 built.
HKP 4C for Swedish Navy. Powered by Rolls-Royce Gnome H.1200 turboshaft engines, 8 built.
KV-107IIA-17 (CT58-140-1)
Long-range transport version for the Tokyo Metropolitan Police Department, 1 built.
KV-107IIA-SM-1 (CT58-IHI-140-1M1)
Firefighting helicopter for Saudi Arabia, 7 built.
KV-107IIA-SM-2 (CT58-IHI-140-1M1)
Aeromedical and rescue helicopter for Saudi Arabia, 4 built.
KV-107IIA-SM-3 (CT58-IHI-140-1M1)
VIP transport helicopter for Saudi Arabia, 2 built.
KV-107IIA-SM-4 (CT58-IHI-140-1M1)
Air ambulance helicopter for Saudi Arabia, 3 built.


Military Operators

Military operators of the CH-46 (Bright red = Active; Dark red = Former)
Military operators of the CH-46 (Bright red = Active; Dark red = Former)
 Saudi Arabia
  • Ministry Of Interior (MOI) - General Civil Defence Agency (GCDA)
 United States

Civilian operators

Columbia Helicopters Inc Boeing Vertol 107 C-FHFW and Boeing 234 N245CH rest on the company pad in Aurora, Oregon
Columbia Helicopters Inc Boeing Vertol 107 C-FHFW and Boeing 234 N245CH rest on the company pad in Aurora, Oregon
 United States

Former operators

Specifications (CH-46)

General characteristics

  • Crew: 4: 2 pilots, 1 crew chief, 1 aerial gunner/observer, 1 tail gunner
  • Capacity: 25 troops
  • Length: 45 ft 8 in fuselage (13.92 m
  • Fuselage width: 7 ft 3 in (2.2 m))
  • Rotor diameter: 51 ft (16 m)
  • Height: 16 ft 8.5 in (5.1 m)
  • Disc area: 4,100 ft² (380 m²)
  • Empty weight: 15,537 lb (7,047 kg)
  • Loaded weight: 17,396 lb (7,891 kg)
  • Max takeoff weight: 24,300 lb (11,000 kg)
  • Powerplant:General Electric T58-GE-16 turboshafts, 1,870 shp (1,400 kW) each



See also

Related development

Comparable aircraft

Related lists

  • Donald, David ed. "Boeing Vertol Model 107 (H-46 Sea Knight)", The Complete Encyclopedia of World Aircraft. Barnes & Nobel Books, 1997. ISBN 0-7607-0592-5.

External links

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Published in July 2009.

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