Boeing Vertol CH-46 Sea Knight

The Boeing Vertol 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".

Development

Piasecki Helicopter was a pioneering developer of tandem-rotor helicopters, with the most famous previous helicopter being the H-21 "Flying Banana". Piasecki Helicopter became Vertol in 1955 and work began on a new tandem rotor helicopter designated the Vertol Model 107 or V-107 in 1956. The V-107 prototype had two Lycoming T53 turboshaft engines, producing 877 shp (640 kW) each.^[4] The first flight of the V-107 took place on 22 April 1958.^[5] 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".^[6]

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.^[6] 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.^[2] 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.^[2] Boeing had acquired Vertol in 1960 and renamed the group Boeing Vertol.^[6]

The helicopter was first procured in 1961^[7] to meet the medium-lift requirements of the Marine Corps.^[8] 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.^[2] 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.^[9]

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^[2] 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.^[9] Along with the USMC CH-46Ds, the Navy received a small number of UH-46Ds for ship resupply.^[10] Also, approximately 33 CH-46As were upgraded to CH-46Ds.^[9]

The Marines also received 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.^[2] 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.^[9] 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.^[7] 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.^[7]

On 15 December 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.^[7]

Design

The CH-46 has tandem contrarotating rotors 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 can be folded for on-ship operations.^[9]

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. An internal winch is mounted in the forward cabin and can be used to pull external cargo on pallets into the aircraft via the ramp and rollers. A belly sling hook (cargo hook) which is usually rated at 10,000 lb (4,500 kg). could be attached for carrying external cargo. Although the hook is rated at 10,000 lb (4,500 kg)., the limited power produced by the engines preclude the lifting of such weight. It usually has a crew of three, but can accommodate a larger crew depending on mission specifics. For example, a Search and Rescue variant will usually carry a crew of five (Pilot, Co-Pilot, Crew Chief, Swimmer, and Medic) to facilitate all aspects of such a mission. A pintle-mounted 0.50 in (12.7 mm) Browning machine gun is mounted on each side of the helicopter for self-defense.^[9] Service in southeast Asia resulted in the addition of armor with the guns.^[2]

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 contain fuel tanks with a total capacity of 350 US gallons (1,438 L).^[9]

Operational history

Military

Known colloquially as the "Phrog", and used in all Marine combat and peacetime environments since its introduction.^[11] 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".^[12]

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.^[13]

While the United States Navy retired the airframe on September 24, 2004, replacing it with the MH-60S Knighthawk,^[1] the Marine Corps plans to maintain its fleet until the MV-22 is fully fielded.^[14] In March 2006 Marine Medium Helicopter Squadron 263 (HMM-263) was deactivated and redesignated VMM-263 to serve as the first MV-22 squadron.^[15] The replacement process is expected to continue through the other medium helicopter squadrons into 2014.

Civilian

The Civilian version, the BV 107-II Vertol^[16] 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.^[16] As of 15 December 2006 Columbia Helicopters has purchased the Type certificate of the Model 107 from Boeing.^[17] Currently the company is seeking FAA issuance of a Production Certificate to produce parts with eventual issuance of a PC to produce aircraft.

Variants

US versions

Total U.S. H-46 production amounted to 525, ending in 1971.^[18]

Model 107 

Company model number for basic prototype, 1 built.^[19]

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.^[20]

Model 107M 

Company model number for military transport of BV-107/II-2 for the United States Marine Corps.^[18]

YHC-1A 

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.

HRB-1 

Original designation before being renamed as CH-46A before delivery under the 1962 United States Tri-Service aircraft designation system.

CH-46A 

Medium-lift assault and cargo transport and SAR helicopter for the USMC, fitted with two 1,250 shp (935 kW) General Electric T58-GE-8 turboshaft engines. Previously designated HRB-1. 160 built for USMC, 1 static airframe.

UH-46A 

Medium-lift utility transport helicopter for the United States Navy. Similar to the CH-46A. 14 built.

HH-46A 

Approximately 50 CH-46As were converted into SAR helicopters for the United States Navy base rescue role.

RH-46A 

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.

UH-46B 

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.

YCH-46C 

YHC-1A redesignated in 1962. United States Army retained 2, NASA used 1 for vertical autonomous landing trials (VALT).

CH-46D 

Medium-lift assault and cargo transport helicopter for the USMC, fitted with two 1,400 shp (1,044 kW) General Electric T58-GE-10 turboshaft engines. 266 built.

HH-46D 

Surviving HH-46A were upgraded and a small number of UH-46Ds were converted into SAR helicopters. SAR upgrades included the addition of an external rescue hoist near the front crew door and a 18-inch X 18-inch Doppler RADAR system located behind the nose landing gear, which provided for automatic, day/night, over-water hovering capability for at sea rescue. Additionally a "Loud Hailer" was installed opposite the crew entrance door for communicating with downed aviators on the ground or in the water.

UH-46D 

Medium-lift utility transport helicopter for the US Navy combat supply role. Similar to the CH-46D. 10 built and one conversion from CH-46D.

CH-46E 

Approximately 275 -A, -D, and -F airframes were updated to CH-46E standards with improved avionics, hydraulics, drive train and upgraded T58-GE-16 and T58-GE-16/A engines.

HH-46E 

Three CH-46Es were converted into SAR helicopters for Marine Transport Squadron One (VMR-1) at MCAS Cherry Point.^[21]

CH-46F 

Improved version of CH-46D, electrical distribution, com/nav update BUNO 154845-157726. Last production model in the United States. 174 built, later reverted to CH-46E.

VH-46F 

Unofficial designation of standard CH-46F used by HMX-1 as VIP support transport helicopter.

CH-46X 

Replacement helicopter based on 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 (4,200 shp).^[22]

XH-49 

Original designation of UH-46B.

Canadian versions

CH-113 Labrador 

Search and rescue version of the Model 107-II-9 for the Royal Canadian Air Force.^[23]

CH-113A Voyageur 

Assault and utility transport version of the Model 107-II-28 for the Canadian Army. Later converted to CH-113A Labrador when the Canadian Forces acquired the CH-47 Chinook.^[24]

Swedish versions

HKP 4A 

Boeing Vertol 107-II-14, used originally by Air Force for SAR, 10 built.^[25]

HKP 4B 

Boeing Vertol 107-II-15, mine-layer/ASW/SAR helicopter for Navy, three built and one conversion from Boeing-Vertol civil prototype.^[26]

HKP 4C 

Kawasaki KV-107-II-16, advanced mine-layer/ASW/SAR helicopter for Navy,eight built.

HKP 4D 

Rebuilt HKP 4A for Navy as SAR/ASW helicopter, four conversions.^[27]

Japanese versions

^[28]

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.

KV-107II-16

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.

Operators

Military operators

 Saudi Arabia

• Ministry of Interior: General Civil Defence Agency (GCDA)

 United States

• United States Marine Corps^[29]
  • VMR-1
  • HMM-161 1966–2009
  • HMM-162 1965–2005
  • HMM-163
  • HMM-165
  • HMM-166 1986–2010
  • HMM-261 1966–2008
  • HMM-262
  • HMM-263 1967–2005
  • HMM-264 1968–2009
  • HMM-265 1965–
  • HMM-266 1983–2006
  • HMM-268 1979–
  • HMM-364 1967–
  • HMM-365 1967–2009
  • HMM-764
  • HMM-774 1970–

Civilian operators

 Canada

• Helifor Canada Corp (under lease from Columbia Helicopters)

 United States

• Columbia Helicopters

Former operators

 Japan

• Kawasaki Helicopter System, LTD
• Tokyo Metropolitan Police Department
• Japan Air Self-Defense Force^[30]
• Japan Ground Self-Defense Force^[30]
• Japan Maritime Self-Defense Force

 Sweden (All in Storage)

• Swedish Armed Forces
• Swedish Air Force
• Swedish Navy

 Thailand

• Royal Thai Army^[31][32]

 United States

• New York Airways
• Pan Am
• United States Navy

Notable accidents and incidents

• On December 9, 1999, a CH-46D Sea Knight, Naval Bureau Number 154790 assigned to Marine Medium Helicopter Squadron 166 (HMM-166) crashed during a boarding exercise off the coast of San Diego, California, killing 7 U.S. Marines.^[33][34] The pilot landed the CH-46D short on the deck of the USNS Pecos, causing the left rear tire and strut to become entangled in the safety netting at the back of the ship. The pilot increased power to pull up, unaware of the entangled landing gear. The landing gear failed to break free, causing the helicopter to nose over and plunge into the ocean, rolled over, and sank. Eleven Marines were freed themselves of the wreckage and survived. However, 7 Marines perished when the helicopter sank. The Navy instituted helicopter evacuation training for all U.S. Marines shortly after the accident.

Specifications (CH-46)

General characteristics

• Crew: 5: 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) with armor, guns, and ammunition
• Max takeoff weight: 24,300 lb (11,000 kg)
• Powerplant: 2 × General Electric T58-GE-16 turboshafts, 1,870 shp (1,400 kW) each

Performance

• Maximum speed: 165 mph (145 kn; 265 km/h)
• Combat radius: 184 mi (160 nmi, 296 km)
• Ferry range: 420 mi (360 nmi, 676 km)
• Service ceiling: 14,000 ft (4,300 m)
• Rate of climb: 2,045 ft/min (10.4 m/s)
• Disc loading: 4.2 lb/ft² (21 kg/m²)
• Power/mass: 0.215 hp/lb (354 W/kg)

Armament

• Guns: 2× Door mounted GAU-15/A .50 BMG (12.7 x 99 mm) machine guns (optional), 1 Ramp mounted M240D 7.62 x 51 mm machine gun (optional)

Aircraft on display

• Canadian Warplane Heritage Museum, Canada
• Kakamigahara Aerospace Science Museum, Kakamigahara, Gifu, Japan^[35]
• Kawasaki Vertol 107-II - Kawasaki Good Times World, within Kobe Maritime Museum, Kobe, Hyōgo, Japan.^[36][37]
• Japan Air Self Defense Force Hamamatsu Air Base Publication Center, Hamamatsu, Shizuoka, Japan^[38]
• Aeroseum, Gothenburg, Sweden - Boeing Vertol/Kawasaki KV-107-II (CH-46), Hkp 4C, c/n 4093, Fv 04072 "72"^[39]
• Carolinas Aviation Museum, Charlotte, North Carolina, USA has Medal of Honor Mike Clausen's CH-46
• Flying Leatherneck Aviation Museum, San Diego, California, USA has "Lady Ace 09" of HMM-165. The CH-46 took part in Operation Frequent Wind and was used to evacuate Ambassador Graham Martin, the last United States Ambassador to South Vietnam from the United States Embassy, Saigon on 30 April 1975.
• National Museum of Naval Aviation
• National Museum of the Marine Corps
• USS Midway Museum in San Diego, California

See also

Related development

• CH-113 Labrador
• CH-47 Chinook
  

Aircraft of comparable role, configuration and era

• Piasecki H-25
• Sikorsky S-61
  

Related lists

• List of active United States military aircraft
• List of military aircraft of the United States
  

References

Notes

Bibliography

• 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

• CH-46D/E Sea Knight and CH-46 history pages on U.S. Navy site; CH-46 page on USMC site
• CH-46 product page and CH-46 history page on Boeing.com
• Columbia Helicopters — Largest Civilian Operator of BV/KV Model 107
• Boeing Vertol 107 & H-46 Sea Knight on Airliners.net
• Kawasaki Helicopter Services (S.A.) Ltd.