subject: Old DHC-6 Twin Otter Versus New Havilland 400 Series Turboprop Aircraft In Commuter Air Services In Africa & Other Parts Of The World [print this page] Old DHC-6 Twin Otter Versus New Havilland 400 Series Turboprop Aircraft In Commuter Air Services In Africa & Other Parts Of The World
Considered to be one of the most successful aircraft ever built, many of the hundreds of de Havilland Twin Otter turboprop aircraft are still flying in commuter air services in Africa and other parts of the world.
This is no mean achievement considering that the high-wing turboprop was first conceived in 1964 and entered service in 1966 with most of the type being involved in tough flying conditions carrying everything from passengers and animals to the proverbial kitchen sink into modern highly-equipped airports or fields which hardly warrant the description of an "airstrip".
The DHC-6 Twin Otter uniquely incorporates ailerons designed to droop in unison with double slotted wing flaps to improve the STOL capability of the workhorse. The fixed tricycle under-carriage is easily converted to operate on large oversize "Tundra" wheels suitable for sandy desert-type conditions, or perform as a float plane sitting on pontoons to support the 5670-kg aircraft in operations in areas such as Alaska, northern Canada and other parts of the world where lakes or swamps dominate.
In nutshell, the ability to attach on the aircraft any type of landing gear means the aircraft can go almost anywhere in the world at any time of the year.
A claim the manufacturers of the DHC-6 Twin Other stand by even to this day is that no other counterpart of similar category of aircraft offers more diverse application from a single airframe.Which,in a sense ,places it on a par with the legendary Douglas DC-3 Dakota.
Intended primarily for service with commuter or third-level airlines, the Twin Otter has nevertheless seen wide use with operators in Argentina,Canada,Chile,Ecuador,Ethiopia,Central Africa,France,Haiti,Jamaica,Nepal,Norway,Panama,Paraguay,Peru,the USA,Venezuela,and the mountain kingdom of Lesotho, in Southern Africa.
The first DHC-6 Twin Otter series 100 entered service in1966 and was soon followed by the larger 200 series aircraft. This series differed by having increased baggage capacity in the lengthened nose compartment of the fuselage and was certificated at a higher gross weight.
After a hundred of these aircraft had been manufactured, the production of the Series 300 was introduced, these having more powerful Pratt and Whitney PT6A-27 engines which increased the maximum takeoff weight considerably.
All specifically manufactured floatplane versions, however, irrespective of series, retained the shorter fuselage nose section of the original Series 100.
The success of the Twin Otter is its remarkable STOL function and comparative ease of maintenance.
Today, the largest operator of the Twin Otter aircraft in the world is the Canadian Ken Borek Air, which has 30 or more Twin Otters in operation around the world, primarily in both Antarctica operating on wheel/skis as well as on floats ferrying holidaymakers for the Maldivian Air Taxi company to island resorts within the Maldivian archipelago.
The consequences of age inevitably will be the demise of these aircraft which have successfully served in many varied applications. With restrictions placed on "aged commercial aircraft" in some countries, worldwide availability of these aircraft is becoming increasingly limited.
When production of the 100,200 and 300 series ended in 1988, in all 844 Twin Otters had been manufactured by the de Havilland Aircraft Company.
Approximately 600 of these aircraft are still operating in service around the world a tribute to their ruggedness and ability to withstand "punishment".
There is a saying among operators of the Twin Otter, that the only aircraft that can replace an "Old Twin Otter "will be a "New Twin Otter."
Enter The New Twin Otter
After the de Havilland Company closed its aircraft manufacturing plants in Downsview,Ontario,and underwent multiple ownership changes, Viking Air BC,a Canadian aircraft manufacturer with close ties in support of de Havilland products, is now continuing with the DH heritage line of "out of production" aircraft from its manufacturing facility in British Colombia.
The introduction of the all new Viking series 400 Twin Otter is the "New Twin Otter".
The culmination of a three year process of development, manufacturing, testing and certification ended in June 2010 when the first Viking Series 400 Twin Otter was revealed for certification by the Canadian Transport Authority.
The Amended Type Certification was granted by Transport Canada to include the Series 400 Twin Otter with the other DHC-6 Series 100, 200, and 300 aircraft.
The Viking Series 400 Twin Otter incorporates over 800 changes developed to modernize and improve upon the value and safety of the original production model, of which the most significant change is the integration of the Honeywell Primus Apex avionics suite.
The updated flight deck features two primary flight displays (MFDS) with high resolution LCD screens, providing wider viewing ability and cross cockpit scanning.
The Primus Apex's flexible architecture supports the aircrafts unsurpassed capability with a comprehensive software package, allowing each operator the ability to select the configuration best suited for its specialized operating environment.
Composite fuselage elements are incorporated into non-structural components such as the air stair, exit doors, nose and baggage compartments, and miscellaneous fairings in order to reduce the empty weight and increase payload.
Under the amended type certification the unpressurized airframe remains "lifted" at 66000 hours subject to mandatory maintenance and inspection programmes.
Other changes include upgraded Pratt & Whitney PT6A-34 engines offering even better "hot and high" performance capability.
The structural elements of the aircraft remain unchanged from the older versions of the 300 series. At the time of writing the first of two production aircraft had been delivered to the launch customers, Zimex Aviation, of Switzerland, and Air Seychelles, in the Indian Ocean archipelago. The improvements on performance data and range are yet to be evaluated by customer reports.
Guardian Twin Otter
In response to customer demand from foreign military and government agencies, Viking has introduced the Guardian 400 Twin Otter variance which is a medium range maritime patrol and SAR (search and rescue) aircraft.
Designed for extreme operating environments, the Guardian 400 will include a restricted category increased take-off weight and extended range internal patrol fuel tanks, allowing for operational sorties of over 10 hours in duration. In addition, the Guardian 400 will be outfitted with an electro-optical and infrared imaging turret which can be linked to either the flight deck Honeywell Primus Apex multi-function display, or on a separate cabin console. Other features will include spotter camera, laser range finder and a laser illuminator.
Sales for the Series 400 Twin Otter are strong with a current backlog standing at over $ 200-million .With delivery slots sold out until mid-2014,demand for this popular and versatile aircraft is high, proving the types on-going popularity around the world.
If its performance to date is any indication, there is little doubt that the new Viking Twin Otter will match or even better the overall performance of its "forefathers" and eventually become an aviation legend in its own right.
