Alexander Mladenov details the PZL M28 operated all over the world in a variety of military and civil roles
Length: 13.10m (43ft)
Wingspan: 22.06m (72ft 4.5in)
Height: 4.90m (16ft 1in)
Cargo hold length: 5.26m (17ft 3in)
Cargo hold width: 1.73m (5ft 8.5in)
Cargo hold height: 1.72m (5ft 8in)
Empty weight: 4,354kg (9,601lb)
Max take-off weight: 7,500kg (16,534lb)
Max landing weight: 7,500kg (16,534lb)
Max payload: 2,300kg (5,070lb)
Long-range cruise speed: 132kts (244km/h)
Max operating speed: 192kts (355km/h)
Stall speed: 65kts (120km/h)
Max rate of climb: 12.29m/s (2,420ft/min)
Take-off run at MTOW and sea level: 255m (837ft)
Landing roll: 235m (771ft) G-limits: +3/-1
Service ceiling: 25,000ft (7,620m)
Cruise altitude: 9,840ft (3,000m)
Max range at 10,000ft: up to 860nm (1,592km)
Endurance: up to 6.2 hours
PZL M28 SKYTRUCK
The PZL Mielec M28 Bryza short take-off and landing (STOL) light airlifter is currently manufactured and marketed by US aerospace giant Lockheed Martin, which acquired the PZL Mielec’s Sikorsky parent company in November 2015. Undoubtedly, this could be defined as a great irony of fate, as the type traces its origins in the late Soviet Union; it was designed and tested by the Antonov Design Bureau based in Kiev, Ukraine. The prototype took to the air on its maiden flight in September 1969; mass production of the aircraft, designated as the An-28, was handed over to the Polish aerospace industry in the early 1980s. Before the breakup of the Soviet bloc in Eastern Europe, the main customer for the An-28 was the Soviet Union’s giant airline Aeroflot, which took a total of 157 examples built by WSK-PZL in Mielec, Poland, out of 170 examples rolled out between 1984 and 1992. Aeroflot used the An-28 as a short-range transport in remote regions with poor airfield infrastructure, because the type was able to use short unpaved airstrips.
After the dissolution of the Soviet Union and the emergence of the market economy in Poland, An-28’s manufacturer PZL Mielec had to look elsewhere for new customers in order to keep the production line running after Aeroflot ceased taking deliveries of the type. The Polish military emerged as the first big new operator, placing an order for two An-28s during 1988, which continued with more orders in the early and mid-1990s.
In the early 1990s, an export version was developed, designated the M28 and dubbed Skytruck, with the original aim of certification in the United States and Europe, in an effort to improve the sales prospect of the type. However, this proved to be a protracted and difficult process. As a result, the M28, which took to the air for the first time on July 24, 1993, obtained its Polish civil type certificate in March 1996, but was eventually certified in the United States under FAR Part 23 rules in 2004. European EASA type certificate followed in 2005.
The first production standard M28 was designated the M28-02, the improved M28- 05 version was introduced in 1999.
The Skytruck achieved export success in Latin America, where the Venezuelan National Guard (the largest customer) and the Venezuelan Army ordered 13 and 12 aircraft respectively. The first National Guard aircraft was delivered in December 1996 and the Army aircraft arrived in country in 2000 and 2001.
Two Skytrucks were delivered to the Royal Nepalese Army (the first customer in Asia) in 2002, followed by four to the Indonesian National Police in 2004 and two to the Vietnamese People’s Air Force in 2005.
The Royal Jordanian Air Force, the last known M28 customer and the first one in the Middle East, has purchased an undisclosed number, the first of which was delivered in December 2014, at which time at least three more are believed to have been on order.
The M28 programme got an additional sales boost in the late 2000s when 18 were ordered by Air Force’ Special Operations Command, designated and named the C-145A Combat Coyote. The first was delivered to the 6th Special Operations Squadron, 919th Special Operations Wing at Duke Field, Florida, in 2009. US company Sierra Nevada Corporation undertook modifications on the aircraft prior to delivery to meet the US Air Force specifications. Ironically, the 6th SOS superseded its retired MC-130E Combat Talons in 2013 with the C-145A Combat Coyote. The list of the roles assigned to the squadron’s C-145As included infiltration, exfiltration, resupply and training foreign air force personnel.
The M28 is a braced high-wing monoplane. Use of twin-turpboprop engines enable the aircraft to operate with a full payload even under demanding hot-and-high conditions. The wings are fitted with two-section double-slotted flaps, manual/automatic spoilers, ailerons and leadingedge slats. The tail unit comprises twin-fins, rudders and a fixed-incidence tail plane. Among the M28’s most notable features (applicable to both the An-28 and M28) is the aerodynamic layout, which makes stall almost impossible even when the control column is held in an extreme rear position, thanks to the automatic wing slats. In the event of engine failure, the upper surface spoiler, ahead of the aileron on the opposite side of the failed engine, opens automatically. As a result, the wing with the failed engine drops by only 12º in five seconds instead of 30º without spoiler activation, thus easing handling qualities with one engine inoperative. Another smart design feature implemented by Antonov is the fixed tailplane slat, which improves handling at high angle-ofattack flight during climb out.
In the event of tailplane failure, a thermal antiicing system prevents build-up on the tailplane when flying in icing conditions, such that ice accretes on the slat instead of the tailplane, thereby retaining controllability.
The M28’s non-pressurised fuselage is a conventional all-metal semi-monocoque structure. The heated, ventilated and sound-proofed cabin can be configured with 18 seats for passenger transport with rear clamshell doors and the ability to be rapidly reconfigured for medical evacuation (with six stretchers, eight seated patients and two attendants). The cabin can be configured with a cargo roller floor, an integrated overhead hoist (rated at 1,540lb/700kg) and a heavy cargo system, with capacity for three cargo palettes weighing up to 1,408lb (2,000kg). Alternatively, there is a provision for installing a cargo pod (with 600lb/300kg capacity) under the fuselage. The robust undercarriage design is a nonretractable trailing-link tricycle type, with single-wheel and large low-pressure tyres, and oleo-pneumatic shock absorbers on each unit. Main landing gear units are mounted on small stub-wings extending from each side of lower fuselage curving forward to serve as mudguards. The nose landing gear unit is steerable by 50º to the left and the right.
The powerplant consists of two Pratt & Whitney Canada PT6A-65B turboprops, driving Hartzell five-blade propellers with full feathering and reverse pitch capability. Average fuel consumption in cruise flight at 10,000ft (3,050m) altitude is 591lb (268kg) per hour. The fuel system comprises two centre-section and two outerwing integral tanks with a total capacity of 2,278 litres (4,000lb). In addition, an auxiliary tank with a 2,030-litre (3,550lb) capacity can be fitted in the cabin for extra-long ferry flights. Flight crew comprises a pilot and co-pilot each with full dual controls and bulged side windows for visibility.
The aircraft boasts a powerful ice protection system for the wings, tailplane and fin leading edges using engine bleed air, enabling it to fly into known icing conditions. Engine air intakes are anti-iced by engine oil, while the propellers, spinners, pitot heads and windscreens are antiiced electrically.
The M28-05 comes equipped with Bendix/ King flight-navigation avionics suite certified for VFR/IFR, day and night flight operations and flying into known icing conditions; a manual or automatic flight control system (autopilot) and an RDR-2000 weather radar. The extended M28 navigational capability also includes precision
POLISH MILITARY VERSIONS
The first two An-28s were purchased by the Polish Ministry of Defence for evaluation during 1987. These were delivered to the Polish naval aviation arm in 1988, the same year the Polish military ordered a tailor-made military version.
The M28B Bryza family was developed in several military variants in the early-to-mid 1990s, with first deliveries reported in 1992. All aircraft were initially powered by PZL TWD-10B engines each rated at 945shp (705kW).
The M28TD (An-28TD) was the first variant, equipped with a ramp sliding under the fuselage and capacity to carry up to 17 paratroopers or 3,857lb (1,750kg) of cargo.
The Polish Navy ordered the M28RM Bryza-RM version, equipped for the maritime patrol/ rescue co-ordination mission, with a crew of five comprising two pilots and three system operators. The prototype took to the air for the first time in 1992, equipped with the Polishmade ARS-100 surface search radar housed in an under fuselage radome. Production aircraft feature the ARS-400, capable of tracking up to 100 sea targets at a maximum range of 115 nautical miles (213km).
Mission equipment comprises an AFA-39 camera, Chelton DF-707-1 direction finder, ACR/ PLB-14 radio marker buoys, RDR-82 weather radar and a pair of SAM-100NM illumination bombs for search and rescue operations at night (suspended on racks on undercarriage supports), as well as three six-seat dinghies. To enable unobstructed operation of the search radar, the Bryza-RM is equipped with a semi-retractable undercarriage. The aircraft was powered by TWD-10B engines driving three-blade propellers, later upgraded to the PZL-10S with five-blade Hartzell propellers in addition to the RDR-2000 weather radar.
In 2001, two Polish Navy M28Bs – the first aircraft built for the Polish military, originally delivered in 1988 – were upgraded with the MS5000 surveillance system, based on an Ericsson side-looking radar for monitoring sea surface contamination. These machines received the new designation Bryza-E.
In the early 2000s, the Polish Navy commenced an ambitious upgrade of its M28 fleet for use in the anti-submarine warfare role (designated the Bryza-1RM/bis) equipped with the SRM-80 maritime surveillance system. The full upgrade package comprised a MAG-10 magnetic anomaly detector in an extended tail boom, the ARS-800 search radar, HYD-10 sonobuoy signal processing system, an ESM10 electronic support measures system and a FLIR Systems Star SAFIRE II electro-optical/infrared system. The prototype took to the air for the first time in January 2003, but the integration process proved to be too big a challenge and as a result the project was abandoned. Only one aircraft, serial number 0810, received the full package prior to the project being abandoned.
In the early 1990s, the Polish Air Force ordered the upgraded M28B1, the first was delivered in October 1994. In 2008, 12 more new M28s, fitted with glass and NVG-compatible cockpits, were ordered, but the order was reduced to eight the following year. All eight aircraft were delivered in a basic transport configuration between 2011 and 2014. By 2017, the Polish Air Force fleet comprised 18 M28BTDs for transport and parachuting and 13 M28B/PTs for passenger and transport duties.
The Polish Border Guard is also among the domestic customers of the Bryza, with one aircraft equipped for maritime surveillance and border patrol taken on strength in 2006. This aircraft is equipped with a Star SAFIRE IV HD electro-optical/infrared system housed in an extended nose, an ARS-400M search radar, IR/UV scanner, searchlight, expanded communication suite and an NVG-compatible cockpit.
The Combat Coyote is well suited to the special ops role, because of its versatility and impressive STOL performance. An M28 can land on unprepared airstrips under 1,000ft (345m) long, thanks to its high-lift wings, thrust reversing propellers, heavy-duty undercarriage and large, low-pressure tyres. When operating from unpaved airstrips, the engines are protected by inlet particle separators. An M28 can transport up to 5,000lb (2,300kg) of cargo for 235 nautical miles (450km), flying at a cruise speed of 192kts (356km/h). Stall speed is only 53kts (98km/h) with flaps extended and engines in idle mode. Air Force Special Operations Command has used its C-145A fleet on operations in Afghanistan where aircraft flew from short, semi-prepared landing strips. One example was written off there 2011. The C-145A can use strips shorter than 305m (1,000ft), with a maximum gross weight of 16,535lb (7,500kg), a maximum cruise speed of 181kts (335km/h) to a maximum range out to 1,010 nautical miles (1,872km).
When onboard supplemental oxygen equipment is used by the aircrew, the M28 can climb to a 25,000ft (7,622m) service ceiling.
In May 2015, Air Force Special Operations Command decided to retire a number of its C-145A fleet, citing a change in mission requirements. At the time, some 11 aircraft of the then 16-strong fleet were earmarked for long-term storage with the 309th Aerospace Maintenance and Regeneration Group at Davis-Mountain Air Force Base, Arizona. The remaining five C-145As were set to remain in use, mainly to support pilot training and undertake crew proficiency sorties. In October 2016, several counties had expressed interest in the retired C-145As. Kenya requested acquisition of six aircraft under the Excess Defense Articles (EDA) programme, three Combat Coyotes were allocated by the US Government. Two C-145As are reported to have been authorised under the EDA programme for delivery to Costa Rica, two more to Estonia and two to Nepal.
Earlier this year Lockheed Martin revealed ambitious plans to boost sales of the M28 Skytruck, which are currently in stagnation. PZL’s Regional Sales Manager North and South America, Ingmar Wyczalek, said the company sees a strong future for its STOL turboprop airlifter with both civil and military operators. These will be found in those parts of the world that lack established infrastructure and prepared runways.
He also revealed the current fleet of M28 aircraft numbers about 100 aircraft (as of February 2017), mostly operated by military and paramilitary operators. Wyczalek claims Lockheed Martin has decided to pursue a strategic aim to penetrate civil markets in North and Latin America, Africa and the Asia- Pacific region. The company is aiming to get between 10 and 15 sales annually, a target that is expected to benefit from Lockheed Martin’s huge experience of the transport aircraft sector with the C-130 Hercules.
In late March, Lockheed Martin launched a two-month sales tour to 13 cities in Argentina, Brazil, Columbia, Ecuador, Mexico, Panama, Tobago and Trinidad. The company sees a need in each country for a powerful, versatile and low-maintenance aircraft capable of flying cargo and passengers into unprepared landing strips and dropping relief supplies or paradropping troops jungle or mountain locations and at small strips at sea level. During a stop at Jacarepaguá airport in Rio de Janeiro on April 3, to attend the LAAD 2017 aerospace and defence exhibition, the M28 showcased its versatility to the Brazilian military. Capabilities demonstrated included the M28’s STOL performance, taking off in just 1,797ft (548m) with 5,070lb (2,300kg) of cargo on board.