10, 1967, Bill Lear's approximately 60% share of the venture was acquired by the Gates Rubber Company of Denver, Colorado, for US$ 27,000,000. Lear remained on the company board until April 2, 1969, when the company was merged with Gates Aviation Corporation and was renamed Gates Learjet Corporation. In 1971, the first Model 25 powered by a Garrett TFE731-2 turbofan engine was flown. This aircraft later became the successful Learjet 35. That year, the company was awarded the President's "E" Award for promoting export sales. In 1974, the worldwide Learjet fleet had exceeded the one-million flight hours mark and, in 1975, the company produced its 500th jet, both industry firsts. By late 1976, the company increased monthly aircraft production to ten. On August 24, 1977, the Learjet 28 made its first flight. It was based on the Learjet 25, but received a completely new wing fitted with winglets. These resulted in both improved performance and fuel economy and inspired the name "Longhorn" for the short-lived Learjet 28/29 and for some of the more successful models that followed. On April 19, 1979, the prototype for the Model 54/55/56 series made its first flight, and on July 7, 1983, a standard production Model 55 set six new time-to-climb records for its weight class. In 1984, Gates Learjet announced the start of their Aerospace Division, a high technology endeavor. However, by the end of the year the company had ceased production of its commercial jets in an effort to reduce inventories. This lasted until February 1986, when the company headquarters were transferred to Tucson, Arizona, and production was restarted both in Wichita and Tucson. On September 10, 1985, the Aerospace Division was awarded a contract to produce parts for the Space Shuttle's main engines. In 1987, Gates Learjet was acquired by Integrated Acquisition and the next year the name was changed to Learjet Corporation. By January 1989, all production had been moved from the Tucson facility back to Wichita with an employment of 1,250. Acquisition by Bombardier In 1990, Canadian company Bombardier Aerospace purchased the Learjet Corporation. The aircraft were then marketed as the "Bombardier Learjet Family". On October 10, 1990, the Learjet 60 mid-sized aircraft had its first flight, followed on October 7, 1995, by the Learjet 45. In October 2007, Bombardier Learjet launched a brand new aircraft program, the Learjet 85. It was the first FAR Part-25 all-composite business aircraft. Bombardier