The Twin Otter is a design that has endured and continues to attract new customers. Dino Carrara and Tom Kaminski examine Viking Air Limited’s Twin Otter special mission variant that is being targeted at government and military roles.
Air Limited has breathed new life into the Twin Otter with its new production Series 400 and is further building on the type’s versatility by developing the Guardian 400. The 19-passenger DHC-6 Twin Otter was developed by de Havilland Canada, and first flew in prototype form on May 20, 1965.
Built as an unpressurised rugged short take-offand landing (STOL) commuter aircraft, it features a high wing and fixed tricycle landing gear and twin turboprop engines. It was designed to carry passengers and cargo into remote unimproved locations and be able to operate with wheels, skis and floats. Six Series 1 prototypes were powered by two 550shp (410kW) Pratt & Whitney Canada (PWC) PT6A-20 engines.
Early Series 100 and 200 models that followed retained the PT6A-20, but the Series 300 was fitted with more powerful 620shp (462kW) PT6A-27 powerplants. In addition to the prototypes, 114 Series 100, 115 Series 200 and 615 Series 300 Twin Otters were manufactured. Production ended in 1988 when the last example left the company’s Downsview, Ontario factory. Throughout its service life the Twin Otter airframe has proven itself to be adaptable and has taken on numerous roles, including aerial survey, Antarctic support, environmetal monitoring, search and rescue, parachute operations, medevac, and test and evaluation.
In 2005, Viking purchased the DHC- 6 Product Support and Spare Parts business, as well as the Commercial Service Centre (CSC) from Bombardier Aerospace, which had previously acquired de Havilland Canada from Boeing in 1986.
Incorporated in 1970 and headquartered in Sidney, British Columbia, Canada, Viking became the exclusive spare parts manufacturer and distributor in 1983 for the DHC-2 Mk I Beaver, Mk III Turbo Beaver, and DHC-3 Otter aircraft. In 2006 it acquired the Type Certificates for seven legacy, out-of-production de Havilland Canada aircraft including the DHC-6.
The Type Certificate transfer established Viking Air Limited as the Original Equipment Manufacturer (OEM) for the Twin Otter and gave it the exclusive rights to re-start production.On July 17, 2006, Viking unveiled plans to produce a new Twin Otter version incorporating more than 800 design changes. The new Series 400 included a Honeywell Primus Apex integrated avionics suite, modernised electrical and lighting systems and composite components. There is also a colour weather radar, an interactive navigation system, dual GPS or Loran-C navigation systems, enhanced ground proximity warning system (EGPWS) and a traffic awareness and collision avoidance system (TCAS). The aircraft is powered by 750shp (559kW) PWC PT6A-34 turboprop engines, flat-rated at 620shp (462kW).
A modified DHC-6-300 (MSN 434) served as the Series 400 proof-ofconcept prototype and first flew at Victoria International Airport, in British Columbia, on October 1, 2008 wearing the registration C-FDHT. The first new-build Twin Otter, MSN 845, carried out its initial flight from Viking’s final assembly plant at Calgary International Airport, Alberta, on February 16, 2010. Viking received Transport Canada Type Certification on June 24 and delivered the first Twin Otter Series 400 to Swiss commercial operator Zimex Aviation at the Farnborough International Airshow in July. European Aviation Safety Agency (EASA) and US Federal Aviation Administration (FAA) certifications followed on November 12, 2010 and July 9, 2012 respectively.
Since production of the Series 400 began, Viking has produced over 100 examples for civil customers. The Twin Otter design has proved popular over the years with governments and air arms. This has continued with the new Guardian 400 variant and the company states it offers “a specialised solution for surveillance, search and rescue, critical infrastructure support, and a range of other special missions applications”.
CUSTOMERS
The US Army became the first military customer for the Series 400 when it ordered three examples in February 2008. These aircraft were to replace two DHC-6-100 versions (designated UV- 18As), operated by the US Army Golden Knights parachute team. Prior to delivery, the new aircraft, named UV-18Cs, were modified with an air-operable roll-up main cabin door and sidewall seating for up to 16 parachutists. The first UV-18C was accepted by the US Army Fixed Wing Project Office in September 2012. The second and third followed in November 2012 and the new variant entered service on January 31, 2013.
The design of the Twin Otter has lent itself to many different roles over the years. To try to capitalise on this, Viking developed the Guardian 400. The company says: “The aircraft can be quickly re-deployed and adapted for surveillance, transportation, search and rescue, medevac and additional mission profiles to provide a low-cost, force-multiplier and invaluable asset to government and military fleets.” Some of the roles are sensitive in nature and so the company is not able to comment on some customers.
Speaking to Aviation News, Rob Mauracher, Viking’s executive vice president, sales & marketing, was keen to stress the versatility of the aircraft. He stated that in addition to the standard undercarriage it can be fitted with floats for amphibious operations, wheel skis for both a hard surface or operating from ice and snow or with Intermediate Flotation Gear (IFG) for a soft field landing capability, and changing from wheels to floats can be accomplished in 48 hours. He added: “We can configure the Guardian 400 bespoke to what the customer wants as there are a wide range of equipment options.” An Airborne Technologies Self Contained Aerial Reconnaissance (S.C.A.R.) pod can be carried o n a wing hard point (two can be fitted on each wing) with a range of systems.
This includes a side-looking airborne radar (SLAR) antenna, Visual Detection and Ranging (ViDAR) camera system from Sentient Vision Systems (which includes moving target indication), a Hensoldt Argos EO/IR camera, electronic intelligence (ELINT), signals intelligence (SIGINT) and communications intelligence (COMINT) equipment, multi-spectral HDTV camera, satellite communications and self-defence detection equipment.
A Leonardo Osprey active electronically scanned array (AESA) radar can also be accommodated in the pod which can be used for maritime and land surveillance, high-resolution ground mapping, small and low-speed target indication, and air-toair surveillance, tracking and intercept capability.
Other optional systems include the Link YE Mk II data link, Automatic Identification System (AIS – for tracking shipping), Cobham 935 for direction finding, Saab Civil Aircraft Missile Protection System (CAMPS), Teledyne Optech’s T-4800 and T-7200 aerial cameras, and an external steerable searchlight, such as the TrakkaBeam A800.
With a view to military use, the cockpit of the Guardian is also night vision compatible.
MULTI-ROLE SENSOR AIRCRAFT
An alternative to the S.C.A.R.-pod option is the Guardian 400 Multi-Role Sensor Aircraft (MRSA), which features a redesigned nose for a Bendix/King ART-2000 digital weather radar and a Leonardo (Selex) Osprey 30 multi-mode surveillance AESA radar. The system includes synthetic aperture radar (SAR); a moving target indicator; plus longrange search and track while scan modes.
It is also equipped with a 15in (38.1cm) L-3 WESCAM MX-15HDi electro-optical/ infrared (EO/IR) turret. Alternately the 14in (35.6cm) FLIR PolyTech UltraForce 350 EO/IR turret can be installed with a laser rangefinder and a laser spotter camera.
Both turret options are retractable, which prevents water spray from affecting the system when the aircraft operates on water or in poor weather conditions.
The redesigned nose of the MRSA could be used to carry a range of equipment such as the Swedish Space Corporation SLAR and larger non-retractable EO/IR turrets like the L3 WESCAM MX-20 or Zeus Leo III.
The aircraft’s 384 cu ft (10.87m³) cabin permits it to be customised to support multiple missions. One Guardian 400 configuration features two observer bubble windows, one observer station in the forward area of the cabin and a pair of fold-up crew seats in the rear along with a lavatory. There is room for up to six two-screen workstation consoles. Another option is an Airborne Technologies tactical workstation system which includes highdefinition touchscreen monitors, data/ voice/video recorder, a mission management unit, radios and a hand controller for camera targeting.
Additionally, the Guardian 400 can be quickly converted to utility configurations that allow it to carry up to 19 passengers or two litter patients when operating in the medical evacuation role.
The Guardian 400 has an increased maximum take-offweight over the standard Series 400, 12,500lb (5,670kg) standard compared to 14,000lb (6,350kg) increased gross weight.
In a press release on the first day of the 2019 Paris Air Show, Mr Mauracher said: “We have been engaged in the special missions arena for many years, and have put together a team of partners, led by Airborne Technologies, with extensive experience integrating flexible architecture solutions that are customised to suit each customer’s specific mission requirements.”
The Guardian 400 demonstrator attended the Paris event and in September embarked on a nine-month world demonstration tour to visit 34 countries. Highlighting its capability, Mr Mauracher stated: “For extended duration missions several extra fuel tanks can be fitted to give an endurance of over ten hours.
Depending on the cabin configuration selected the lavatory can be installed at the front or rear and there is also the option for a galley.” The first customer for this variant was Global Aerospace Logistics (GAL) of Abu Dhabi in 2009 which purchased nine Series 400s, four being Guardian 400s. The deal also included interchangeable VIP/ high- density interiors, tactical avionics and sensor packages. The aircraft are operated for the United Arab Emirates government and feature upgraded hot and high performance PT6A-35 engines, and Intermediate Flotation Gear (IFG) which enables operations on the loose sand found in the Gulf region.
The United Arab Emirates Air Force & Air Defence’s 18 Group (Joint Aviation Command), already operated three Series 300 Twin Otters in the ISR role. Deliveries of the GAL aircraft began in December 2013 and concluded in February 2015.
Six Guardian 400s were ordered by Vietnam on May 5, 2010 and have been optimised for maritime patrol. Ikhana installed an Israel Aerospace Industries’ ELTA Systems EL/M-2022A(V)3 Multi-Mode Surveillance radar system and a lightweight 10in (25.4cm) Stark Aerospace MiniPOP day/night surveillance turret. In addition to maritime work, these aircraft also get tasked with SAR, cargo transport and paratroop missions. Deliveries to Vietnam People’s Navy’s Naval Aviation Brigade 954 began in November 2013 and the aircraft formally entered service on June 17, 2014.
The sale of a Guardian 400 to the Panama National Air & Naval Service was revealed in November 2016. The aircraft was delivered to the Air Transport Squadron in December 2016 and formally accepted at Lieutenant Octavio Garrido Air Base on January 23 the following year. The purchase of a second Twin Otter was announced in October 2017 and it was handed over to the same unit in January 2018.
Three other air arms have ordered the Series 400. The Peruvian Air Force purchased 12 examples in December 2010 and deliveries began in July 2011, concluding in December 2014. The aircraft are operated by Grupo Aereo de Transporte 42’s Escuadrón Transporte Aereo Nacional de Selva 42 (421st Jungle National Air Transport Squadron) at Colonel FAP Francisco Secada Vignetta International Airport in Iquitos. They are tasked with patrol, SAR, transport and supporting special forces. This air force had been the largest military operator of the Twin Otter having previously flown three -100s and 16 -300s of which two remain in service.
With the popularity of the Twin Otter among air arms well established over the years and the Guardian 400 tailored to this market, it seems likely Viking will continue the success it has achieved in the civil sector with the type.
