The Magni500 sounds just about as loud as you’d expect for an airplane engine — but technically speaking, this is no engine. It’s a 750-horsepower, all-electric motor that MagniX has been revving up to turn an aircraft propeller at full power. That’s a significant milestone for MagniX, which has offices in Redmond, Wash., and in Australia. The successful ground tests signal that the company is getting closer to having the Magni500 flight-tested on a Harbour Air plane in British Columbia. “This milestone is significant not only for MagniX, but for the electric aviation industry in general, because it is now the world’s largest all-electric motor (560 kw /  750HP) that has been installed in an aircraft-like system, turning a real full-sized aircraft propeller and controlling prop pitch via a governor,” MagniX CEO Roei Ganzarski told GeekWire in an email. “This was the last step before installing such a system on an aircraft — in our case, the Harbour Air Beaver,” he said. “We are now testing our third 750HP motor.” Ganzarski said MagniX has completed more than 50 hours of multiple full-power, full-flight profile tests on the Magni500 at its engineering center on Australia’s Gold C...