Never content to rest on its laurels, in 1966 the Beech Aircraft Corporation launched a series of upgrades to the new King Air that drew increased sales from business aviation and military customers.
By 1965, Beechcraft dealers and distributors were selling the Model 90 at an accelerated pace. Not only was the turboprop-powered airplane proving to be an enormous success in the marketplace, but its growing popularity also resulted in a steady stream of orders that flowed into the factory in Wichita, delighting both dealers, distributors and most importantly, Olive Ann Beech.
Salesmen across the United States and in Europe were kept busy as both longtime and new customers lined up to plunk down their cash deposits for the new King Air. It was becoming clear that the great gamble taken by the company’s board of directors a few years before was paying off handsomely. Had he lived to see the Model 90, there is little doubt that Walter Beech would have thrown his full support into the program, proving once again that at times risks must be taken to advance aviation.
Mr. Beech had proven that attitude time and again, first with the Travel Air Type “R” racing monoplane of 1929. Painted a brilliant scarlet red, the sleek, single-seat ship easily won the Thompson Cup at the National Air Races that year, soundly defeating the best the U.S. Army and Navy, as well as worthy commercial adversaries, could muster.
Then in 1932, amid a devastating economic depression that had crippled commercial aviation in America, he and Olive Ann dared to risk everything they had gained in aviation to co-found the Beech Aircraft Company and locate it (of all places!) in a leased building of the defunct Cessna Aircraft Company. Sales of the company’s radical Model 17R cabin biplane, designed and engineered by associate Ted Wells, totaled zero for the first two years of the Beechcraft organization. Cash and operating capital were nearly exhausted, but Walter hung on and never gave up. By 1934 the infant company was slowly gaining a solid financial footing and the future looked promising.
From a historical and technical viewpoint, it is reasonable to conclude that the Model 17 Staggerwing resembled the Model 90 King Air in that both airplanes represented a break with the past. In its own unique way, each airplane had advanced that state-of-the-art in commercial aviation and pointed toward the future.
Such was the determination of Walter H. Beech – a determination to succeed despite tremendous odds that made him a legend in his own time. The King Air carried on that tradition.
Following the Model 90’s formal introduction in 1964, the company had built 112 airplanes and had implemented a global product support program designed to keep the new Beechcraft flying. As with any new Beechcraft airplane, owners and pilots were encouraged to share their opinions of the aircraft and offer suggestions regarding how the Model 90 could be improved. In parallel with customer input, company pilots and engineers were continually evaluating every aspect of the King Air’s “personality.”
They eventually created a list of changes that, combined with those from owners and operators, were aimed at taking the Model 90 to the next level in terms of overall value for the dollar. Although corporate pilots were enthusiastic about the ease of operating the airplane’s Pratt & Whitney PT6A-6 turboprop engines, these powerplants lacked reversing propellers that would significantly decrease landing distances – an important consideration since many Model 90s were being operated from small airports with relatively short runways.
Another concern was the airplane’s pressurization system. Although a distinct improvement over the days when nonpressurized cabins required passengers and crew to use supplemental oxygen at higher altitudes, the pressurization systems was limited to 3.4 pounds per square differential (psid). Customers wanted that number increased to take advantage of the Model 90’s ability to climb to and cruise at altitudes above 20,000 feet.
During 1965, Beechcraft engineers addressed these as well as other technical, performance and systems issues to create the Model A90. Although the airplane was essentially identical to the Model 90 externally, the majority of upgrades were transparent to the owners/operators and resided entirely within the airframe and engines.
More powerful Pratt & Whitney PT6A-20 engines, each rated at 550 shaft horsepower (shp) for takeoff, 538 shp for climb and 495 shp for the cruise phase flight, replaced the PT6A-6 powerplants of the A90’s predecessor. To address the concern about runway landing distance, the A90 was the first of the King Air series to receive fully reversing propellers. These units proved highly effective at reducing landing rollout, particularly when operating on rough, unimproved landing strips.
As for the aircraft’s pressurization system, maximum differential was increased to 4.6 psid that provided passengers and crew with a sea level cabin at 10,000 feet altitude and an 8,000-foot cabin at a cruising altitude of 21,000 feet. The upgraded system finally matched the cabin to the airplane’s performance capabilities and provided a welcome increase in comfort.
First flight of the A90 occurred Nov. 5, 1965, and following Federal Aviation Administration (FAA)
certification, production commenced for the 1966 model year. Priced at about $400,000, the Model A90 offered a lot of performance and utility and 206 airplanes were built before the A90 was superseded on the production line by the Model B90 King Air.
The B90 took to the air for the first time April 13, 1967. It possessed only minor upgrades to airframe systems but retained the A90’s PT6A-20 engines and reversing propellers. The B90 entered production in 1968, and 184 airplanes were manufactured before the Model C90 appeared for the 1971 model year.
In addition to being popular with commercial operators, the Model A90/B90 was soon pressed into service with the U.S. Army. Designated U-21A (Beechcraft designation was A90-1), the Army bought 110 airplanes from 1966-1968 and the majority were assigned to units serving in Southeast Asia during the Vietnam War, chiefly performing liaison, transport, surveillance and utility missions which they accomplished in admirable fashion.
Unlike the commercial A90 and B90, however, the Army’s airplanes were unpressurized and featured square windows reminiscent of the Model 65 Queen Air series. To facilitate handling of large cargo, such as spare engines, propellers and other war material, the U-21A fleet was equipped with a cargo door on the left side of the fuselage that incorporated an airstair door.
A small number of airplanes were built by the factory specifically to meet Army specifications for special missions such as intelligence gathering and battlefield communications. Officially dubbed “Guardrail” by the Army, four of these unique aircraft were designated RU-21A and another 10 served under the designation RU-21D with special antenna arrays installed vertically on the wings and empennage surfaces.
To conduct special missions operations of a more clandestine nature, the Army ordered and equipped 17 U-21Gs. All were built and delivered in 1971. These airplanes were designed specifically to accommodate sophisticated electronic countermeasures and communications equipment in the cabin and in pods at each wingtip.
The aircraft were not the first built as the Army’s new special missions’ platform. In 1967, the factory built three RU-21B (A90-2) and two RU-21C (A90-3) aircraft. In 1971, Beech Aircraft built and delivered 16 “Guardrail” platforms designated RU-21E and RU-21H (A90-4) that served the Army in the role of electronic surveillance and other related missions. These airplanes were powered by Pratt & Whitney PT6A-28 engines each rated at 620 shp to accommodate a higher maximum gross weight of 10,900 pounds.