01/31/2010. Remarks by Bernhard Klein: "During the 1950s and 1960s, Howard Aero Inc. of San Antonio, Texas, USA, had been remanufacturing military surplus Lockheed Navy PV-1s and PV-2s for the executive market, but while the Howard 500 twelve to fourteen passengers transport bore a strong resemblance to these aircraft, it was a substantially new design, and all Howard 500s had completely new fuselages.
The fuselage differed from the VP-1 and VP-2 models in being redesigned from the outset for pressurization, and the wings were designed wet. The pressurization system maintained a differential of 6.75 lb/sq.in (0.47 kg/sq.cm) which was greater than any other prop or turboprop executive aircraft on the market at the time and maintained a sea level cabin pressure at up to 16,000 ft (4,879 m).
The only major components taken directly from its Lockheed forebears were the outer wing panels taken from surplus Venturas and undercarriage taken from surplus Harpoons. Howard purchased wing and fuselage jigs from Lockheed to use as patterns for jigs for the new aircraft.
The engines chosen were new, higher-power and lighter-weight versions of the Pratt & Whitney R-200 that had been developed for the Douglas DC-6. Propeller hubs were taken from Vought Corsairs, four-blade propellers from Lockheed Constellations, and spinners from DC-7s."