This propeller was flown by Pan American Airways, most likely on twin-engined, eight-seat Sikorsky S-38 amphibian aircraft, for about 440,000 km (275,000 miles) and 2,500 hours in Mexico and Central America. It was previously exhibited by the Aluminum Company of America in the early-1930's as an example of the uses for light metal alloys in aircraft. The S-38 was the first commercial success for the fledging Sikorsky Corporation.
A metal ground-adjustable propeller was flown earlier by Lindbergh on the Spirit of St. Louis, and was the best available technology, pointing the way toward fully-controllable pitch propellers for the high performance aircraft of the 1930s. Hamilton Standard acquired the technology from its predecessor, the Standard Steel Propeller Company, which worked directly with the propeller unit of the Army Air Service at McCook Field to improve propeller design. Ground-adjustable-pitch propeller sales provided the revenue that kept Hamilton Standard going during the dark financial days of the Depression.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.