The Boeing CH-46 Sea Knight Helicopter has been the workhorse of the Navy and Marine Corps medium-lift squadrons since it entered service in June 1964. It was developed as the Vertol Model 107, which was also being designed for the civilian market, and was first flown on April 22, 1958. An initial trial batch was ordered by the Army but this was redued when Vertol published drawings of the enlarged Model 114 which became the Chinook. By 1960 Vertol had been absorbed into Boeing.
The Marines became interested in the type as a replacement for their piston-engined H-34 Seahorse. The Model 107M won the Marine Corps competition in 1961, and the first of what became designated the CH-46A Sea Knight entered service in October 1962. The Navy also became interested and ordered 14 of the similar UH-46A for combat support; these tended to be largely used for VertRep (Vertical Replenishment), transferring supplies from ship to ship, and the Navy later orderd a further 10 UH-46Ds.
he Marines were pleased with the CH-46A which they used as a troop transport; when it became available they ordered a total of 246 CH-46Ds which had increased power and new rotor blades. These were followed by 174 CH-46Fs with further improvments, including to the avionics; fiver were completed as VH-46Fs fro use as VIP transports.
In the early 1970s a proposal to increase the performance and combat tolerance included the fitting of crash attenuating seats, crash and combat-resistant fuel system, a new navigation system, plus new engines together with fiberglass rotor blades. A couple of CH-46s wer thus modified and resulted in most surviving CH-46Ds and CH-46Fs being converted to this standard. The Navy modified some of its CH-46s for the search and rescue role, with a winch, and these were redesignated HH-46D.
The Marines’ CH-46 Sea Knights are central to their warfighting capability, providing rapid transport from ship to beach and further forward as required. Once troops are ashore, the CH-46 role changes to re-supply, with a continuing cycle of bringing ammunition, food and other stores from ship to shore and providing aeromedic evacuation of casualties. The CH-46 has no weapon carrying capability and carries no integral armament but can be fitted with machine gun in the crew door for self defense. It can carry up to 22 troops or up to 5,000lbs of cargo either internally or underslung.
The C-46 first saw service during the Vietnam War and has been used in every conflict since in which the marines have been involved. Ten Marin Corps squadrons of CH-46s were deployed to the Middle East during Operation Desert Storm.
The Navy UH-46 Sea Knight fleet is scheduled to be replaced by September 2004 with the MH-60S Knighthawk. Final production model was the CH-46E. Some 174 were delivered to the Marine Corps who have been looking toward the CV-22 Osprey as a replacement, but its development has been fraught. As a result the CH-46 Helicopter will probably solider on for a few more years yet.