Enstrom F-28

The Enstrom F-28 is a light piston-engined helicopter produced by the Enstrom Helicopter Corporation of Menominee, Michigan, United States. Configured with a single main rotor and a three-seat cabin, it is used for training, private transport, and police patrol work. The type received Federal Aviation Administration certification in April 1965 and, together with its streamlined 280 derivative, forms the basis of Enstrom's piston product line; approximately 1,200 aircraft of all Enstrom types had been built by 2007.

Development

Enstrom delivered its first helicopter shortly after FAA type certification of the F-28 in April 1965, with 13 initial-production aircraft completed. The improved F-28A followed in May 1968 with modified gearing raising effective power to 205 hp, and 316 were built. The turbocharged F-28C was certified in December 1975 (177 built) and the F-28F Falcon in December 1980 (132 built). A parallel line of aerodynamically refined models began with the 280 Shark, certified September 1974, and continued through the 280F and the 280FX, certified January 1985. Experimental turbine developments included the T-28, fitted with a 220 shp Garrett AiResearch TSE 36-1, and the Spitfire Mark I and Mark II Tigershark conversions by Spitfire Helicopters Inc., one of each built.

Design

The F-28 and 280 use Lycoming horizontally opposed piston engines virtually identical to those installed in general aviation fixed-wing aircraft. The F-28F is powered by a 225 hp Lycoming HIO-360-F1AD four-cylinder, direct-drive, air-cooled engine with a turbocharger and throttle correlator. Main rotor diameter is 32 ft 0 in with a NACA 0013.5 section and 804 sq ft disc area; length is 29 ft 3 in and height 9 ft 0 in. Empty weight is 1,570 lb and maximum take-off weight 2,600 lb. Maximum speed is 97 kn, economical cruise 89 kn, range 241 nmi, endurance 3 hours 30 minutes, service ceiling 12,000 ft, and rate of climb 1,450 ft/min. From the F-28C onward the tail rotor was moved from the starboard to the port side; the 280FX added landing gear fairings, redesigned cabin-top air intakes, and a relocated horizontal stabiliser with vertical end plates.

Operational History

Most civil operators are small commercial and flight training organisations flying one or two aircraft. Military and government users have included the Chilean Army, the Colombian Air Force, which received 12 F-28F trainers in 1994, the Peruvian Air Force, Army and Naval Aviation, the Pakistan Army Aviation Corps, the Venezuelan Air Force, and the Pasadena Police Department. On 22 October 1986 an F-28F carrying WNBC 660 AM traffic reporter Jane Dornacker crashed into the Hudson River after a clutch installed incorrectly failed at 75 ft; Dornacker died. A 280FX crash at Erie, Colorado on 26 January 2015, caused by a cracked main rotor spindle, led the FAA to issue an Emergency Airworthiness Directive on 12 February 2015 grounding more than 300 helicopters pending magnetic particle inspection.

Variants

• F-28: Initial production version with 195 hp Lycoming HIO-360-A1A or A1B, certified April 1965, 13 built.
• F-28A: Modified gearing raising effective power to 205 hp, certified May 1968, 316 built.
• F-28C: Turbocharged 205 hp HIO-360-E1AD or E1BD, higher gross weight and port-side tail rotor, certified December 1975, 177 built.
• F-28F Falcon: 225 hp HIO-360-F1AD with improved turbocharger and throttle correlator, certified December 1980, 132 built.
• 280FX: 280F development with gear fairings, revised intakes and relocated stabiliser, certified January 1985, 80 built by 1998.