Vickers Viscount refurbished and saw new service with African operators; sales of these second-hand aircraft continued into the 1990s. It is believed that the last airworthy Viscount, 9Q-COD, last flew in January 2009 for Global Airways in the Democratic Republic of the Congo. See "List of accidents and incidents involving the Vickers Viscount". Vickers Viscount The Vickers Viscount was a British medium-range turboprop airliner first flown in 1948 by Vickers-Armstrongs. A design requirement from the Brabazon Committee, it entered service in 1953 and was the first turboprop-powered airliner. The Viscount was well received by the public for its cabin conditions, which included
Vickers hardness test the material. The fin attachment pins and sleeves in the Convair 580 airliner were specified by the aircraft manufacturer to be hardened to a Vickers Hardness specification of 390HV5, the '5' meaning five kiloponds. However, on the aircraft flying Partnair Flight 394 the pins were later found to have been replaced with sub-standard parts, leading to rapid wear and finally loss of the aircraft. On examination, accident investigators found that the sub-standard pins had a hardness value of only some 200-230HV5. Vickers hardness test The Vickers hardness test was developed in 1921 by Robert L. Smith and George E. Sandland