The U.S. Department of Defense issued Technical Specification 153 in 1960 for a Light Observation Helicopter (LOH, or Loach) capable of performing a wide variety of tasks. Everything from transport, observation, attack, evacuation and escort was covered by this spec.
Surprisingly, a dozen companies took part in the competition. Hiller and Bell ended up as finalists, but Bell was eventually eliminated and Hughes ended up being included. Five flying egg prototypes were requested and delivered by November 1963 when flight testing/trials began. The low per-unit construction cost guaranteed that Hughes would win the competition, but that wasn’t the only factor in the equation.
The OH-6 Cayuse (re-designated by the Army from Hughes 369) set 23 world records in 1966 including those of distance, altitude and speed. Eventually, 1434 were delivered to the U.S. Army by the time the program wrapped up in 1970. In the midst of such a successful run, Hughes went ahead and began development of a civilian Model 500 variant.
Hughes had built four additional prototypes for its own use, and from these the civilian commercial version resulted in 1966 with a 317 shp Allison 250-C18A engine de-rated to 278 horsepower. It was marketed as the Model 500. Later, one of the four prototypes was modified with a 5-bladed main rotor system. Subsequent development resulted in the “D” model, available commercially in 1976.
By the time Viking got its hands on the 500, I had spent a couple of thousand hours flying Model 47s. My favourite was always the light and maneuverable G2. I found the G4 ungainly and “heavy”, even with the powered collective. Given its size compared to the G2, to me it was just one ugly son of a gun. Obviously the G4, with its larger cabin and engine, did a better job of transporting two passengers, but there was just something about it that wouldn’t let it grow on me. Call me old-fashioned if you will.
When 1974 rolled around I was given my 500 endorsement at the Kenora base. I was never so happy to leave behind the plodding world of the 47G-4 and jump into the modern, turbine-engined version of what the helicopter world would turn out to be for all of us involved with Viking Helicopters.