This morning I stuffed my old F27B, and I don't know what happened:
Charged LiPo, topped off TX batteries. At the field, did the usual pre-flight: Servo check, engine check, plugs all checked, linkages checked, fuselage checked. It all checked out, nothing out of the ordinary whatsoever.
Launched, plane climbed to altitude. Brought it around for a big circle when I noticed the first oddity: The plane climbed rather steeply. I cut back power and adjusted the trims, regaining control and deciding to bring it down. Before I even got to lining up for approach the engine revved up, the nose dropped into a straight down dive, from about 50-75 feet up. I cut throttle, flipped from low rates to high rates and tried to pull up - but the engine was still screaming and the control input had no effect whatsoever. The plane went straight into the ground, with engine screaming all the way until impact.
The plane is pretty much a loss. I haven't looked at the mess yet but I'm stunned as to what would cause such behavior? It doesn't feel like radio interference, it just seems like an entirely odd loss of control.