Aeropesca Colombia Flight 221 Aeropesca Colombia Flight 221 Aeropesca Colombia Flight 221 was an internal scheduled passenger flight from Florencia Airport to Neiva Airport in Colombia. On 26 August 1981 it was being operated by a Vickers Viscount turboprop airliner registered in Colombia as "HK-1320" when it collided with Mount Santa Elana, an Andean mountain peak, destroying the aircraft and killing all 50 on board. The investigation by the Colombian authorities concluded the probable cause was "continuing VFR in meteorological conditions below the minimum laid down in the Manual of Colombian air routes". The aircraft was a four-engined Vickers Viscount 745D turboprop airliner registered
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