During the 1970s and 1980s, the Beech Aircraft Corporation served up the E90 and F90 King Air using special ingredients drawn from their library of recipes.
As the decade of the 1970s arrived, the Beech Aircraft Corporation had built more than 1,300 King Air business and military airplanes since the introduction of the Model 90 in 1964. Of these, the 1,000th King Air had been delivered in 1972 and eight years later in 1980 the 2,000th King Air, a Model 200, took to the skies. Sales remained strong as did the company’s bottom line thanks to guidance provided through the steady hand of CEO Olive Ann Beech, President Frank E. Hedrick and the board of directors.
By the early 1970s, the Model 90 series had become to the corporate world what the Beechcraft Bonanza had become to the private pilot – the best value for the money – and in 1972 Beechcraft engineers unveiled plans for yet another upgraded version of the venerable King Air. Designated as the Model E90, the airplane benefited from an increase in cruise speed to 285 mph at an altitude of 16,000 feet and a higher service ceiling of 27,620 feet.
First flown Jan. 18, 1972, the E90 could fly up to 1,870 statute miles at its maximum range power setting. Although outwardly the E90 appeared to be a “clone” of the Model C90 upon which it was based, the new King Air sported Pratt & Whitney Canada PT6A-28 turboprop engines each developing 680 shaft horsepower (shp). The engines, however, were each flat-rated at 550 shp. Cabin pressurization remained at 4.6 pounds per square inch (psid) providing passengers and cockpit crewmembers with a comfortable environment.
The Federal Aviation Administration (FAA) issued Beech Aircraft Corporation Type Certificate 3A20 for the E90 April 13, 1972, and during that first year of E90 production, the Wichita factory built 22 of the airplanes. That number, however, had swelled to more than 340 by 1981 when production shifted to the Model C90-1. The last Model E90 to roll off the assembly line was serial number LJ-347.
If Beechcraft management had learned one lesson since the company’s inception in 1932, it was the realization that product development was essential to survival in a capricious marketplace that was rife with competition. During the past 50 years, Beechcraft engineers had become highly proficient at blending the advantages of one airplane with those of another to create a “new” product.
For example, the turbine-powered Model 65-90 was an outgrowth of the Queen Air series, just as the Model 50 Twin Bonanza had provided a basic platform for development of the Model 65. Taking that practice one step further, in the late 1960s Beech Aircraft Corporation combined the lengthened fuselage and pressurized cabin of the Model 100 King Air with a new, wider wing center section and unleashed the Model 200 Super King Air into the business aviation marketplace. The airplane’s spacious cabin and its signature T-tail empennage configuration – the first for a Beechcraft airplane – pushed Beech Aircraft’s pursuit of perfection to new heights.
Continuing the company’s highly successful “cookbook” approach to creating new products, in 1978 engineers combined the T-tail design of the Super King Air with the fuselage and wings of the Model E90. The result was designated the F90 King Air and the preproduction prototype, serial number LA-1, made its first flight Jan. 16, 1978, under the command of company test pilot Marv Pratt. The FAA issued Type Certificate A31CE to the F90 May 18, 1979.
The F90’s market niche would be as a step-up airplane from the E90, and the latest King Air was well equipped to induce corporate aviation to take that step. Although its cabin, which could accommodate up to 10 passengers, was essentially the same as the E90, the F90 possessed major systems and performance improvements compared to its sibling. Chief among these were installation of Pratt & Whitney Canada PT6A-135 engines, each rated at 750 shp. In an effort to reduce noise levels in the cabin, the turboprop engines were mated to new four-blade, full-feathering and reversing propellers turning at a maximum 1,900 rpm or 1,500 rpm at cruise.
Maximum cruise speed increased to 307 mph from the E90’s 285 mph, and initial rate of climb was 2,380 feet per minute (fpm) – another significant advantage over the E90. In addition, maximum certified altitude increased to 31,000 feet. Also, the F90 was the first King Air to use the company’s completely new, state-of-the-art, 28 VDC multi-bus electrical system. The circuitry featured five separate buses, automatic load shedding and solid-state current sensors that provided protection against ground faults (electrical shorts) and quickly isolated a faulty bus, thereby reducing pilot workload.
Initial customer demand for the F90 proved to be strong and 202 airplanes were built between 1979 and 1983. These included seven in 1979, serial numbers LA-2 through LA-8. Production peaked at 75 airplanes in 1981. It is interesting to note that the F90 prototype, serial number LA-1, was later converted to the experimental G90 King Air and given serial number LE-0. The G90’s chief modification compared to the F90 centered on a modified, steeply-sloped windshield installation. The G90 was not placed into production.
For the 1983 model year, Beech Aircraft engineers incorporated technical improvements applied to the C90-1 into the F90-1. These included pitot-type engine cowlings with improved air intake characteristics, particularly at high altitudes, and the use of tapered exhaust stacks. The F90’s PT6A-135 engines were replaced with PT6A-135A versions that each retained a rating of 750 shp. With a span of 45 feet 10.5 inches, the F90-1’s wings contained main fuel cells that held 388 gallons of jet fuel with another 41 gallons available from auxiliary tanks installed in the wing center section.
First flight of the F90-1 prototype, serial number LA-91, occurred Jan. 5, 1981, with Vaughn Gregg at the controls. That event was followed nearly a year later by the first flight of a type-conforming production airplane, serial number LA-202, Dec. 7, 1982, flown by pilot Don Benes of the company’s production flight test department.
Beech Aircraft Corporation had built only 33 examples of the F90-1 when the decision was made, in 1985, to stop production. That decision was based chiefly on the fact that demand for the F90 and F90-1 had declined steadily through the mid-to-late 1980s with only 11 airplanes built in 1983, 1984 and 1985. In 1986 only one airplane, serial number LA-237, was built.
Although the F90 series represented a major improvement over the E90, it was built in much smaller numbers than its stable mate but continued to serve its owners and operators as a unique version of the legendary Beechcraft King Air.