HS 748

The HS 748 was developed during the late 1950s as a move to re-orient Avro towards the civil and export markets after the 1957 Defence White Paper curtailed manned military aircraft development. Announced on 9 January 1959 as the Avro 748, it was envisioned as a replacement for the aging Douglas DC-3s. Powered by a pair of Rolls-Royce Dart turboprop engines, the design focused on a rugged configuration, high performance, and STOL capabilities, differentiating it from competitors like the Fokker F27 Friendship. Compliance with British and American airworthiness standards, along with fail-safe design principles for its structure, was a priority. On 24 June 1960, the first Avro 748 made its maiden flight, and in April 1962, the first production aircraft were delivered to Skyways Coach-Air Limited. Following the absorption of Avro into Hawker Siddeley, the airliner was marketed as the HS 748.

The HS 748 was designed with a focus on ruggedness and superior short takeoff and landing (STOL) performance to enable operations from smaller, more austere airports, even those without modern runways. This STOL capability was achieved through a long, high-lift wing equipped with a unique single-slot flap featuring a hinged flap tab at the trailing edge. The wing was mounted low on the fuselage with dihedral from the root, providing good ground clearance and easy mounting of strong landing gear. Pilots could select from three takeoff flap settings to optimize STOL performance. The design also incorporated straightforward systems and proven components for ease of inspection and repair, even at unprepared airstrips with limited equipment. Its airframe lacked an imposed lifespan and was successfully tested using a water tank for up to 100,000 flight hours.

While primarily designed for civilian use, military variants and adaptations of the HS 748 did exist, most notably the HS 780 Andover, which was configured as a military transport aircraft. However, in its standard configurations, the HS 748 was not equipped with offensive weaponry. Instead, its payload capacity was geared towards transporting passengers or cargo. The Super 748 variant, for example, could carry an 11,323 lb (5,136 kg) payload. Some aircraft were modified to act as bulk fuel haulers, fitted with seven or eight fixed tanks in the cabin, possessing a total capacity of about 7,500 L (1,600 imp gal; 2,000 US gal).

Within its first decade of availability, sales of the HS 748 were reportedly brisk, with 312 aircraft sold by 1976, 259 of which were to export customers. India emerged as the largest single market for the airliner, with Indian Airlines being the largest HS 748 operator, maintaining a fleet of 26 aircraft. It proved popular with numerous commercial operators, particularly in the Caribbean and Latin America, where 63 HS 748s were operated by 11 separate entities. The HS 748 achieved triumphs over competitors like the F27 Friendship, with Philippine Airlines replacing its F27s and remaining DC-3s with the HS 748. Other major civil operators included Aerolíneas Argentinas, VARIG, Thai Airways, LAN-Chile, and Bouraq Airlines. Over one-third of scheduled operations reportedly involved operations from rough airstrips with minimalist facilities, a testament to its STOL capabilities. The HS 748 also served in executive roles for heads of state in Argentina, Brazil, Chile, India, Venezuela, Zambia, Thailand, and the United Kingdom. Militarily, the Royal Australian Air Force procured a fleet of ten HS 748s for navigation training and VIP transport starting in 1968, while the Royal Australian Navy operated two for navigational training from 1973. The HS 748s were also used for electronic warfare training after being fitted with electronic countermeasures (ECM) during the late 1970s.

Main Variants:

• 748 Series 1: The original Avro 748 twin-engined short/medium-range airliner, it was powered by two Rolls-Royce Dart RDa 7 Mk 514 turboprop engines.

• 748 Series 2: Entering production in 1961, the Series 2 featured a higher take-off weight and Mk 531 engines, marking an improvement over its predecessor.

• 748 Series 2A: Introduced in 1967, this variant had a further increase in take-off weight and Mk 532 or 534 engines, becoming one of the more successful British airliners.

• 748 Series 2B: The main production model after Hawker-Siddeley was absorbed by British Aerospace, featuring a 4-foot increase in wingspan, increased gross weight, Mk 536 engines, a modernized cabin, and systems improvements.

• Hawker Siddeley HS780 Andover: This modified version of the 748 design, created for the Royal Air Force, included a kneeling undercarriage, raised tail unit, and rear loading ramp for military transport purposes.

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