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-28. Early licence-built planes were designated PZL An-28. The maritime patrol and reconnaissance variants are named PZL M28B Bryza ("sea breeze").

Design and development
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 highly successful An-2 biplane. The An-28 is substantially derived from the earlier An-14. Commonality with the An-14 includes the high wing layout, twin fins and rudders, but it differs in having a new and far larger fuselage, plus 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 Ukraine. 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 production An-28s. Basic variant, not differing from the Soviet one, was designated PZL An-28 and 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, 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 19 March 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. From 2000, newly produced M28Bs started to be equipped with five-blade propellers as well.

Description
PZL M28 Skytruck
It is a twin-engined high-wing strutted monoplane of all-metal structure, with twin vertical fins and a robust tricycle fixedlanding gear, featuring a steerable nose wheel to provide for operation from short, unprepared runways where hot or high altitude conditions may exist. The M28 is best suited for passenger and/or cargo transportation.

Short takeoff & landing (STOL) capability
Excellent flight handling at low airspeeds
High useful load, mission versatility
Unpaved airstrip operating capability
Easy access through rear cargo door, fitted with a hoist for cargo loading and relocation inside the cabin
High-wing arrangement for protection of engines and propellers against damage when operating from unpaved airstrips
Easy and quick conversion of the cabin interior configuration

Low operating cost
PT6 engines of inverted configuration for efficient protection against foreign object ingression owing to inertial separators installed inside air inlet ducts.

While of conventional design, one notable feature of the An-28 is that it will not stall, due to its automatic slats. An engine failure that would usually induce the wing to drop 30° is combated by an automatic spoiler forward of the aileron that opens on the opposite wing, restricting wing drop to 12° in five seconds.

Operational history
176 An-28s and M28s in all variants were built in Poland by 2006. Most numerous users are former Soviet civil aviation and the Polish Air Force and Navy (about 25 as of 2006), smaller numbers are used by the Polish civil aviation and in the USA, Nepal, Colombia, Venezuela, Vietnam and Indonesia.

On 4 November 2005, a Vietnamese Airforce M28 crashed in Gia Lam district, Hanoi. All three crewmembers died.

On 12 February 2009, The weekly periodical Air Force Times reported that the Air Force Special Operations Command (AFSOC) would receive 10 PZL M28 Skytrucks in June 2009.[2] These aircraft carry the U.S. Air Force model design series (MDS) designation of C-145A Skytruck.

On 27 October 2010, an Indonesian Police Skytruck, registration #4204, crashed in the District of Wangga, Nabire, West Papua, Indonesia after carrying aid for victims of natural disasters in Wasior, West Papua. All five crewmembers died.

Variants
Airframe Variants
PZL An-28
Original variant build under Antonov licence, with PZL-10S (licence TV-10B) engines.

PZL M28 Skytruck
Development variant with redesigned fuselage and wings, new Pratt & Whitney Canada engines, new (western) avionics, 5-blade rotors, and some other minor changes.

PZL M28B Bryza
Militarized variants used by Polish Air Force and Polish Navy, similar to Skytruck, but with PZL-10S engines.

PZL M28+ Skytruck Plus
Prototype of new lengthened variant with more internal space, not in production.

Variants in use by Polish Military

PZL An-28TD
Basic transport variant. Used mainly for transport and paratroop training (2 built).

PZL M28B
Several similar improved transport variants featuring avionics and airframe upgrades: Bryza 1TD (2 built), M28B (3 built), M28B Salon (1 built), M28B TDII, TDIII and TDIV (2 built of each).

PZL M28B Bryza 1R
Maritime patrol and reconnaissance variant (equipped with: 360° Search and Surveillance Radar ASR-400, Link-11 datalink). Used mainly for sea border patrolling, search and rescue operations and protection of the national economical sea zone (7 built).

PZL M28B Bryza 1E
Maritime ecological reconnaissance and patrol variant (2 built).

PZL M28B Bryza 1RM bis
Maritime patrol and reconnaissance variant with submarine detection capability, of 2004 (equipped with: 360° Search and Surveillance Radar ARS-800-2, ejection of single-use hydro-acoustic sonobuoys, Thermal Imaging System (FLIR), magnetic anomaly detector, Link-11 datalink).

Used mainly for sea border patrolling, search and rescue operations and protection of the national economical sea zone (1 built as of 2006).

PZL M28 05 Skytruck
Maritime patrol and SAR variant for the Polish Border Guard, of 2006 (equipped with Search and Surveillance Radar ARS-400M and FLIR system) (1 built as of 2006).

Variant in use by the U.S. Air Force

C-145A
M28 Skytruck in US service. Aircraft received undisclosed modifications.