In the early 1960s Sud-Aviation began the design and development of a twin turbine-powered helicopter that would not only meet a French army requirement for an all-weather tactical and logistic transport, but which would be suitable also for use by other armed forces. The first of two prototypes made its maiden flight on 15 April 1965, and the Anglo-French helicopter agreement (concluded on 2 April 1968) gave Westland Helicopters in the UK joint production of these aircraft. Intended initially for service with the French army and the Royal Air Force, the latter required this helicopter for deployment as a tactical transport.

The fuselage of the SA 330 Puma, as this aircraft has been named, is a conventional all-metal semi-monocoque structure, with the powerplant mounted externally on top of the fuselage shell and forward of the main rotor assembly. The rotor is driven via a main gearbox, with twin free-wheeling spur gears to combine the outputs of the two turboshaft engines to a single main drive shaft. In the event of an engine failure the remaining engine continues to drive the rotor, and should both engines fail the auto-rotating main rotor continues to drive the auxiliary take-offs for the shaft-driven tail rotor, alternator, dual hydraulic pumps, and ventilation fan. The tail boom, which carries the flapping-hinge five-blade tail rotor on the starboard side and a horizontal stabiliser on the port side, is a monocoque continuation of the aft fuselage. Early main rotor blades were of light alloy construction, but those fitted since 1976 are composite units of glassfibre, carbon fibre and honeycomb construction, with anti-abrasion leading edges of stainless steel. The landing gear is of the semi-retracting tricycle type, with twin wheels on each unit, all of which are partly exposed when retracted.

There have been a number of changes in powerplant: the first SA 330Bs for the French army and air force, and the SA 330Es for the Royal Air Force, were powered by Turmo III C4 turboshaft engines with a take-off rating of 990kW; and the SA330C/H military export versions, first flown in September 1968, had originally 1044kW Turmo IVBs, but from the end of 1973 SA 330H aircraft were equipped with 1174kW Turmo IVC engines which include anti-icing of the engine air intakes. The first SA 330F/G civil versions had Turmo IVA engines of 1070kW as first flown on 26 September 1969 and delivered from the end of 1970; but like the SA 330H the SA 330G acquired Turmo IVC engines from the end of 1973; and this latter power-plant is installed also on the SA 330J (civil) and SA 330L (military) helicopters which were introduced in 1976.

Accommodation of the SA 330J provides for a standard crew of two on the flight deck, and the cabin can have 8, 9, or 12-seat VIP layouts, or can seat up to 20 passengers in a high-density configuration, with a toilet and baggage compartment at the rear of the cabin. Equipped with thermal de-icing of the main rotor blades, thermal anti-icing of the tail rotor blades, special intakes and weather radar, the SA 330J can be flown in all weather conditions, including known icing conditions, since receiving certification in this form on 25 April 1978.

First flown in April 1965 the SA.330A was designed as a medium-weight troop transport. Under an Anglo-French agreement in 1967 the SA.330 Puma was developed by Sud-Aviation and Westland Helicopters to fill an RAF and French Army (ALAT) requirement for a medium troop transport helicopter. After several trial examples were built the production of the Puma was started in 1968 with the first UK-built Pumas joining the RAF in 1971. Powered by twin 1115kW Turbomeca Turmo IVC turboshafts the Puma can carry sixteen combat troops at 260kph for a range of 555km. In 1977 a licence was granted for the Puma to be built in Romania.

P.Allen "The Helicopter", 1996

The first discussions which led to the evolution of the SA.330 took place in 1962, when the Armee de Terre made known its requirements for a minimum-size tactical and logistics transport helicopter capable of all-weather operation. At about this time Sud-Aviation were completing two modified examples of the Sikorsky S-58 (which Sud had been building under licence), each of which was fitted with a 1900shp Turbomeca Bi-Bastan shaft turbine engine, and the first of these machines flew on 5 October 1962. The S-58 development was not pursued, but the SA.330, as first envisaged was to have been powered by two 1300shp Bastan VII's and able to transport 12 troops.

When development of the SA.330 and the production of seven test aircraft (two prototypes and five pre-series machines) was authorised by the STAe in June 1963, Turmo III free turbines of the same rating were selected in preference to the Bastan powerplant. The evaluation aircraft were allotted civil registrations F-ZWWN to 'WT, and the first of them made its maiden flight on 15 April 1965; all of these, plus a sixth pre-series aircraft, were flying by mid-1968, and production has now started. Initially this is to meet orders for fifty-four for the Aviation Legere de I'Armee de Terre, forty-eight for the British services and twenty for export.

Although intended primarily as a combat support transport, the SA.330 may also be employed in the ambulance role, accommodating 6 stretchers and 6 sitting casualties; or as a flying crane, with a 2500kg external sling load. In the transport role it can carry up to 20 troops. Other applications include mountain rescue, with a hoist capable of lifting a 175kg load, or executive transport with a 6-seat luxury cabin. The SA.330 carries a crew of 2. The main rotor blades fold back to facilitate stowage, and all landing wheels retract, although they protrude slightly as a safeguard for emergency landings. The aircraft's size and weight put it officially in the light transport helicopter category, for which class it has an excellent performance. An SA.331 project was studied, which would have had an anti-torque jet nozzle at the rear instead of a tail rotor, but this development has not been pursued.