In 1928, Pitcairn purchased a Cierva C.8W and the American manufacturing rights from Juan de la Cierva for his autogiro designs for $300,000. In 1929, Pitcairn formed a separate patent holding company to build autogiros, the Pitcairn-Cierva Autogiro Company, which was later renamed the Autogiro Company of America. Kellett autogyros competed with, and eventually licensed production rights from Pitcairn-Cierva Autogiro Company for $300,000. As a part of the licensing agreement, Pitcairn used Cierva's copyrighted variant of the name autogiro (spelt with an i) as opposed to the currently more common spelling of autogyro which was initially used to bypass his copyright.

In 1929, three prototypes were built with one being demonstrated in the 1929 Cleveland Air Races. Following a fire in November 1929, The first PCA-1 was built and tested the same month. In June 1929,Clement Keys personally bought all the shares of Pitcairn Aviation (The airline and flying school) for 2.5 million dollars, and resold them two weeks later to North American Aviation, which renamed the company Eastern Air Transport, and finally Eastern Airlines. From this point on, Pitcairn focused on autogiros.

In 1931 the company was renamed to the Autogiro Company of America (ACA). In 1931, The Detroit News made history when they bought the first Pitcairn PCA-2 for use as a news aircraft due to it ability to fly well at low altitude and speed, land and take off from restricted spaces and semi-hover for better camera shots. This PCA-2 was the ancestor of today's news helicopters. Also in 1931, pilot James G. Ray landed an autogiro on the South lawn of the White House. Harold F. Pitcairn, the pilot and three other company members of the Pitcairn-Cierva Autogiro Company were present to receive the Collier Trophy for their development of the autogyro.

In 1932, autogyro inventor Cierva was greeted by U.S. President Herbert Hoover, who predicted in the future we would have large transport autogyros.  Amelia Earhart borrowed a company Pitcairn PCA-2 model. She arranged for the National Aeronautics Association to monitor the flight. Members of the New York press and Movietone News were invited to watch. On her second flight, she remained airborne for about three hours and set a woman's autogiro altitude record of 18,415 feet. Later she toured the country for Beech-Nut Packing Company in a bright green autogiro. On the return trip she crash landed in Abilene, Texas earning her a reprimand from the United States Department of Commerce. A second crash at the Michigan state fair, caused an unintended injury of her husband's ankle as he ran to the scene.

In 1933, the parent company and conventional aircraft manufacturing arm, Pitcairn Aircraft Company merged with the autogiro arm, following the end of Mailwing production, and contract air-mail flights.

On December 9, 1936 Juan de la Cierva died in a crash of a KLM DC-2.  As a member of the board of directors of the Cierva Autogiro Company, Pitcairn was shocked to learn shortly afterward that the company had also licensed technology in Europe to the German Focke Achgelis Company creating competition to the autogiro with a practical helicopter, the Focke-Wulf Fw 61.

In 1938, the company was renamed to the Pitcairn-Larson Autogiro company, and again in 1940 to the AGA Aviation Corporation.

In 1942, Pitcairn sold his airfield and facilities to the United States military for $480,000, forming the Naval Air Station Joint Reserve Base Willow Grove. AGA Aviation was now renamed to G and A Aviation, and became part of Goodyear Tire and Rubber. Pitcairn reduced royalties for 19 in house patents and 145 licensed patents to subcontractors of the government during wartime. After 1946, other manufacturers continued to produce helicopters without paying royalties. The company was dissolved in 1948. Pitcairn continued to pursue litigation for use of the patents by other firms in 1951 that stretched into a 1977 Supreme Court Case awarding Pitcairn's estate 32 million dollars. 

Source: Wikipedia