This is a Significant Operational milestone.
The XH-40 was the prototype for the UH-1 Iroquois. Floyd Carlson was the pilot for the first flight. The aircraft is now on display at the US Army Aviation Museum in Fort Rucker, AL.
Note: Some other sources give the first flight date as October 20, 1956
Source: Bell UH-1H Iroquois "Huey" Smokey III (long description), Smithsonian National Air and Space Museum