Loening Aeronautical Engineering Corporation was founded 1917 by Grover Loening and produced early aircraft and amphibious aircraft from 1917. When it merged with Keystone Aircraft Corporation in 1928, some of its engineers left to form Grumman. Loening formed a new enterprise, Grover Loening Aircraft Company, in 1929, which eventually closed in 1933.

Many Loening flying boats were similar in appearance to the later Grumman Duck, featuring a single large float under the fuselage. Leroy Grumman had been General Manager at Loening Aeronautical Engineering Company, and after Grumman and colleagues and co-founders Leon "Jake" Swirbul, Bill Schwendler and Ed Poor struck out on their own following Loening's merger with Keystone, Grumman's new company's initial business strategy was the repair of Loening aircraft for the U.S. Navy. Grumman soon began marketing aircraft of its own, based largely on concepts developed at Loening. Almost the entire early Grumman work force were ex-Loening employees.

Source: Wikipedia