Osceola Mills, Pa.-based Innodyn will be showing off its latest turboprop engine–the TwinPack–later this month at EAA AirVenture in Oshkosh, Wis. Over the past several years the company has been quietly working on fuel-efficient, low-cost 200- to 300-shp turboprop aircraft powerplants with 5,000-hour TBOs. Building on this work, Innodyn has developed the 500-shp TwinPack, which combines two of its 250-shp turbines through a common gearbox. The two-engines-in-one powerplant is estimated to consume about 35 gph at full power, about the same as 500-shp versions of the venerable Pratt & Whitney Canada PT6A. Innodyn said it will start delivering 185- to 250-shp turboprop engines–ranging in price from $26,000 to $34,500 each–to the experimental aircraft market later this year. The company has plans to certify the engines, and several established aircraft manufacturers are said to be interested in the small powerplants. More details about the TwinPack are expected to be released at AirVenture.