BAC One-Eleven BAC One-Eleven The British Aircraft Corporation One-Eleven, also known as the BAC-111 or BAC 1-11, is a British short-range jet airliner used during the 1960s and 1970s. It was the second short-haul jet airliner to enter service, following the French Sud Aviation Caravelle. The aircraft was also produced under licence in Romania during the 1980s as the Rombac One-Eleven. The One-Eleven was conceived by Hunting Aircraft and developed by the British Aircraft Corporation when Hunting merged into BAC along with other British aircraft manufacturers in 1960. The One-Eleven was intended to replace the turboprop Vickers Viscount on short-range routes. The
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