PZL M28 Skytruck

The PZL M28 Skytruck is a Polish STOL light cargo and passenger plane, produced by PZL Mielec, as a development of licence-built Antonov An-28s. Early licence-built planes were designated PZL An-28. The maritime patrol and reconnaissance variants are named PZL M28B Bryza ("breeze").

The Antonov An-28 was the winner of a competition against the Beriev Be-30 for a new light passenger and utility transport for Aeroflot's short-haul routes, conceived to replace the highly successful An-2 biplane. The An-28 is derived from the earlier An-14. Commonalities with the An-14 include a high wing layout, twin fins and rudders, but it differs in having a reworked and longer fuselage, with turboprop engines. The original powerplant was the TVD-850, but production versions are powered by the more powerful TVD-10B, with three-blade propellers.

The An-28 made its first flight as the An-14M in September 1969 in the USSR. A subsequent preproduction aircraft first flew in April 1975. Production of the An-28 was then transferred to Poland's PZL Mielec in 1978, although it was not until 22 July 1984 that the first Polish-built production aircraft flew. The An-28's Soviet-type certificate was awarded in April 1986.

PZL Mielec has become the sole source for the production of An-28s. The basic variant, not differing from the Soviet one, was designated PZL An-28 and was powered with PZL-10S (licence-built TVD-10B) engines. They were built mostly for the USSR until it broke up. The plane was next developed by the PZL Mielec into a westernised version powered by 820 kW (1100shp) Pratt & Whitney PT6A-65B turboprops with five-blade Hartzell propellers, plus some western (BendixKing) avionics (a distinguishing feature are exhaust pipes, sticking out on sides of engine nacelles). Designated the PZL M28 Skytruck, the first flight was on 24 July 1993 and it is in limited production, mostly for export (39 produced by 2006). The type received Polish certification in March 1996, and US FAR Part 23 certificate on March 19 2004.

Apart from the Skytruck, PZL Mielec developed a family of militarized light transport and maritime reconnaissance planes for the Polish Air Force and Polish Navy in the 1990s, with original PZL-10S engines, named PZL M28B in the Air Force and Bryza in the Navy. Since 2000, newly produced M28Bs have been equipped with five-blade propellers.

PZL Mielec was bought by Sikorsky in 2007. Purchased primarily to produce helicopter structures, the company also produces 10 M28s per year. Sikorsky's current owner, Lockheed Martin, has marketed it to the governments of Indonesia, Jordan, Poland, Venezuela, Vietnam, the U.S. and commercial operators. Split equally between commercial and military applications, it competes with the Viking Air Twin Otter, the Let 410 and the Dornier 228.

The M28 is a twin-engined high-wing strutted monoplane with an all-metal airframe, twin vertical fins and a tricycle fixed landing gear. If an engine fails, a spoiler forward of the aileron opens automatically on the opposite wing. This limits the wing drop to 12° in five seconds instead of 30°.

It is capable of Short takeoff & landing (STOL) and hot and high-altitude operations. Aerodynamically deployed leading edge slats when approaching stall speed enable a 64 kn (119 km/h) low stall speed and while the certification landing field is 1,640 ft (500 m), PZL has demonstrated landing in 512 ft (156 m). Inlet air ducts inertial separators and inverted configuration of the PT6 and the high wing configuration protect the engines and propellers against foreign object damage for unprepared runways operations.

Multiple configurations are available: a 19-passenger airliner with 2-1 seating and an underbelly luggage pod; a cargo aircraft with a 1,540 lb (700 kg) hand-cranked hoist option; the most common combi; a VIP transport; a medevac for six litters and seven seats; a search-and-rescue version; a 17-seat paratrooper drop version; an 18-passenger utility cabin and an aerial firefighting version is considered. A crew of two can switch between passenger and cargo configurations in 7 min. Its inward-opening rear doors allow for cargo drops and utility operations as well as passenger boarding.

It can take off in 1,800 ft (550 m) at the 16,534 lb (7,500 kg) MTOW. The maximum payload is 5,070 lb (2,300 kg), and it can carry 5,000 lb (2,300 kg) over 100 nmi (190 km) or 2,500 lb (1,100 kg) with full fuel over 700 nmi (1,300 km).