This is a Notable Operational milestone.
S-47 was the Sikorsky model number assigned to the type and R-4 the military designation. Sikorsky test pilot Les Morris was at the controls. The aircraft was also known as the Vought Sikorsky Model 316A (or VS-316A).
Source: “Vought-Sikorsky XR-4 / YR-4A / R-4A”, Tom Lawrence, 2019 VTOL History Calendar | January 2019, VFS