A few more details have emerged about Cessna's experimental single-engine turboprop. According to airworthiness (PDF) and registration (PDF) records provided by Plane Fax, the presumed N-number of the aircraft, N350CE, is indeed an experimental aircraft intended for research and development and banned from flying over developed areas except for during takeoff and landing. The R&D plane has only two seats and, as is customary with test planes, only those who have business being there are allowed on board. The documents also put to rest speculation on the engine choice for the test article. It's a PT6.
Although Pratt and Whitney Canada says the PT6A-135A puts out 750 horsepower, Cessna is saying it has 500 horsepower in its FAA filings. The engine is 62 inches long and is the same series used in twins like the old Cessna Conquest and the King Air C90. It's also used in the Vazar single Otter turbine conversion, which is a pretty big single. It might fit in a modified Corvalis but a six-place design is also a possibility. Cessna got the paperwork approval for the aircraft in early April and asked for it to be valid for a year. Fresh speculation is that Cessna will announce the program at AOPA Summit in Long Beach in early November.