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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
Beech Aircraft Corporation capitalized on the advantages of the Model 200 Super King Air’s T-tail arrangement by applying it to the F90 and F90-1. Production of both versions totaled only 237 airplanes. (Special Collections and University Archives, Wichita State University Libraries)
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. KA
Ed Phillips, now retired and living in the South, has researched and written eight books on the unique and rich aviation history that belongs to Wichita, Kan. His writings have focused on the evolution of the airplanes, companies and people that have made Wichita the “Air Capital of the World” for more than 80 years.
JUNE 2021
KING AIR MAGAZINE • 29