RD Studios, formerly known as Rising Dawn Studios, is a developer who stays behind sceneries for X-Plane 11 and is now working on the Riverside Municipal Airport (KRAL).
These previews have been shared via their Facebook page, but as well as the X-Plane.org forums. The previews show off some static aircraft located on the airport, buildings, a container or a wooden palette and its PBR effects. The airport is located southwest from Municipal city and southeast from the Los Angels.
Unfortunately, there is no release date information yet. You can follow the RD Studios on their Facebook page here.