Enstrom 280FX Shark (c/n 2143, OK-EFX / currently N136HA), flying display at the 18th Helicopter Show, Hradec Králové, May 2019.
In 1943, Rudolph “Rudy” John Enstrom, an American engineer and aviation enthusiast, began work on his first rotorcraft design. Over the following years, Enstrom designed five different experimental helicopters.
In December 1959, supported by local investors, Enstrom officially established his aviation company, the R.J. Enstrom Corporation. Shortly afterwards, he began developing his first commercial rotorcraft, designated the F-27. At the end of the following year, the helicopter successfully performed its maiden flight.
Initially, the F-27 was conceived as an open-frame rotorcraft with a partially enclosed two-seat cockpit and equipped with a non-rigid, two-blade rotor. However, during further development, the helicopter was fitted with a three-blade rigid rotor and received a fully enclosed fuselage with an additional, third seat. Such upgraded rotorcraft was designated the F-28 and performed its first flight on 27 May 1962.
Although the company had received some pre-orders for the F-28, its financial situation was difficult. In October 1964, Rudy Enstrom left the corporation to take up a position with a non-aviation business.
However, the other shareholders managed to secure financing for the F-28 project, enabling the development to continue. Moreover, its designation and Enstrom branding remained unchanged.
In April 1965, the F-28 received its airworthiness certificate. The first production series, comprising only thirteen examples, was powered by a 195 hp Lycoming HIO-360 engine. Shortly afterwards, the helicopter was fitted with improved gearing that increased output to 205 hp. The upgraded rotorcraft was then designated the F-28A.
In the following years, the company changed hands several times. First, a controlling interest in Enstrom was acquired by Purex Industries. Then, in January 1971, the company was bought by F. Lee Bailey who changed its name to the Enstrom Helicopter Corporation.
Under its new owner, the company developed several modernised variants of the originall F-28 design. These included the 280 Shark which featured an aerodynamically improved fuselage and a 205 hp Lycoming HIO-360-C1 engine (certified in 1974); the F-28C, equipped with a 205 hp turbocharged HIO-360-E1 engine; and the 280C Shark, being an upgraded variant of the F-28C (both certified in 1975).
However, the development of new rotorcraft had a negative impact on the financial condition of the company. In 1979, Bailey sold his stake in Enstrom, but the new owners soon sold it again. This was only the beginning, as in the following years the company was bought and sold roughly ten more times.
Fortunately, the changes in ownership did not halt the development of new rotorcraft variants. In 1980, Enstrom introduced to the market modernised versions of the F-28C and the F-280C, designated the F-28F and the F-280F, respectively. These rotorcraft were equipped with a 225 hp HIO-360-F1 engine and a new turbocharger. Five years later, the series was upgraded with the 280FX, a redesigned and improved variant of the 280F.Then, in 1993, the company developed a larger, turbine-powered version of the 280 Shark series, designated the Enstrom 480.
Despite unstable ownership, Enstrom had manufactured more than 1,300 rotorcraft, of which about 750 remain in service until today. Most are used as utility helicopters and for flight-training duties, including some military operators.
The Enstrom 280FX Shark featured in our Photo of the Week series was manufactured in 2015. Between 2015 and 2023, the rotorcraft was used for training purposes by DSA a.s., an aviation company based in Hradec Králové in the Czech Republic. In mid-2023, the 280FX was acquired by a new owner in the United States and registered as N136HA.
