As well as producing aircraft and building Hispano-Suiza and Lorraine aero-engines under licence, Avia also designed and built their own radial engines. The Rk.17 was a 9-cylinder supercharged model, rated at 360 hp. It was a nine-cylinder version of their Rk.12.
It was a conventional air-cooled radial: nitrided steel barrels with integral fins were screwed into heat treated Y alloy heads. The pistons were also of heat treated Y alloy. The crankcase was cast from heat treated silumin alloy, with some minor parts using magnesium alloy. The single throw two piece crankshaft was linked to the pistons with an I-section Y alloy master rod, with a single piece big end, which carried the other eight piston rods.