he Last Radial Engine Executive Transport Built In The 1960s The Howard Model 500, registration N500LN, one of only two examples remaining airworthy worldwide, is for sale from Courtesy Aircraft Sales.Conceived in the early 1960s by legendary designer Dee Howard, only 17 of the luxurious, ultra-high-performance, stylish piston twins were ever built. The market was moving to turbine power at that time and there was little market for the plane. The Howard 500 is the last FAA transport-category airplane ever certified with radial engines.
