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DHC-3 Otter
DeHavilland Single Otter Harbour Air.jpg
Turbine Otter in Harbour Air livery
Role STOL utility transport
Manufacturer de Havilland Canada
First flight 12 December 1951
Introduction 1953
Status Active
Produced 1951–1967
Number built 466
Developed from DHC-2 Beaver
Developed into DHC-6 Twin Otter

The de Havilland Canada DHC-3 Otter is a single-engined, high-wing, propeller-driven, short take-off and landing (STOL) aircraft developed by de Havilland Canada. It was conceived to be capable of performing the same roles as the earlier and highly successful Beaver, but was overall a larger aircraft.

Design and developmentEdit

When de Havilland Canada began design work on the "King Beaver" (the Otter's original name) in January 1951, it was trying to extend the company's line of rugged STOL utility transports that had begun with the Beaver. The single-engined, high-wing, propeller-driven DHC-3 Otter was conceived to be capable of performing the same roles as the Beaver, but was considerably larger, the veritable "one-ton truck" (in company parlance, the Beaver was the "half-ton truck").[1]

Using the same overall configuration as the earlier and highly successful DHC2 Beaver, the new design incorporates a longer fuselage, greater-span wings, a cruciform tail, and is much heavier. Seating in the main cabin is for 10 or 11, whereas the Beaver can seat six. Power is supplied by a 450-kW (600 hp) Pratt & Whitney Wasp radial. Like the Beaver, the Otter can be fitted with skis or floats. The Otter served as the basis for the very successful Twin Otter, which features two wing-mounted Pratt & Whitney Canada PT6 turboprops.

The Otter received Canadian certification in November 1952 and entered production shortly thereafter.

Operational useEdit

US Army U-1A Otter Running up for Takeoff at the Hue Citadel Airfield, Republic of Vietnam July, 1967

U.S. Army U-1A, July 1967 Hue Citadel Airfield, Republic of Vietnam

PolishOtter

"Polish Otter" note the four blade prop

Turbo Otter on Wheel-Skiis

Turbo Otter on wheel-skis

C-FUKN-Northway-Aviation-DHC-3-Otter-2

A piston-engined Otter on floats

DHC U-1B Otter U.S. Navy Pensacola 15.12.02R

U.S. Navy U-1B (UC-1) Otter at NAS Pensacola, Florida, in 2002

The DHC-3/CSR-123 Otter was used until 1980 by the Royal Canadian Air Force and its successor, the Air Command of the Canadian Forces. It was used in Search and Rescue, as the "CSR" denotes Canadian Search (and) Rescue (type 123). The engine was a Pratt & Whitney R-1340 (1,340 cubic inches) geared engine. The version used in the Otter was geared for lower propeller revolutions and consequently lower airspeed. The electrical system was 28 volts D.C. It was also operated on EDO floats on water and skis for winter operations on snow. The EDO floats also had wheels for use on runways (amphibious). It was used as army support dropping supplies by parachute, and also non-parachute low-speed, low-altitude air drops, to support the Canadian Army on maneuvers. In the end it was operated by the Primary Air Reserve in Montreal, Toronto, Edmonton and Winnipeg, with approximately 10 aircraft at each base, as well as by the RSU (Regular (Forces) Support Units) at those bases. It was usually flown with a single pilot (Commissioned Officer) in the left seat and a Technical Air Crewman (NCO) in the right seat. It was stood down, and the Kiowa helicopter replaced it in Air Reserve squadrons.

Although the Otter found ready acceptance in bush airlines, as in a similar scenario to the DHC-2 Beaver, the United States Army soon became the largest operator of the aircraft (184 delivered as the U-1A Otter). Other military users included Australia, Canada, and India, but the primary role of the aircraft as a rugged bush plane continues to this day.

An Otter crossed the South Pole in 1957 (see Commonwealth Trans-Antarctic Expedition). The Otter is also popular in the skydiving community and can be found in many dropzones throughout the world.

ModificationsEdit

Stolairus Aviation of Kelowna, BC, has developed several modifications for the DHC-3 including a STOL Kit, which modifies the wing with a contoured leading edge and drooped wingtips for increased performance. Stolairus has also developed a 400 lb "upgross" kit which increases the gross weight of the DHC-3 to 8,367 lbs on floats.[2]

Some aircraft were converted to turbine power using a PT6A, Walter 601 (manufactured in the Czech Republic), or Garrett/Honeywell TPE331-10, by Texas Turbine Conversions. The Walter M601E-11 Turbine Engine conversion is manufactured and installed by Stolairus Aviation.

A Polish Pezetel radial engine has also been fitted. Re-engined aircraft have been offered since the 1980s by Airtech Canada as the DHC-3/1000 using current-production 1,000 hp (745 kW) PZL ASz-62 IR radials.[3]

VariantsEdit

DHC-3 Otter
Single-engined STOL utility transport aircraft.
CSR-123 Otter
STOL utility transport aircraft for the Royal Canadian Air Force.
YU-1 Otter
Six test and evaluation aircraft for the U.S. Army.
U-1A Otter
STOL utility transport aircraft for the US Army.
UC-1 Otter
STOL utility transport aircraft for the United States Navy. Later redesignated U-1B Otter in 1962.
DHC-3-T Turbo-Otter
Otters fitted with either Pratt & Whitney Canada PT6A-27 or Pratt & Whitney Canada PT6A-34 turboprop engine.
Airtech Canada DHC-3/1000 Otter
Conversions powered by PZL Kalisz ASz-62IR engines.

Military operatorsEdit

Flag of Argentina.svg Argentina
Flag of Australia.svg Australia
  • Royal Australian Air Force: Two Otters (RAAF serial A100-1 and 2) were in service with the RAAF from 1961 to 1967. The aircraft were used for passenger and freight transport duties at the Weapons Research Establishment, Woomera, South Australia.
    • No. 1 Air Trials Unit
Flag of Bangladesh.svg Bangladesh
Flag of Myanmar.svg Burma
Flag of Cambodia.svg Cambodia
Flag of Canada.svg Canada
Flag of Chile.svg Chile
Flag of Costa Rica.svg Costa Rica
Flag of Ethiopia.svg Ethiopia
Flag of Ghana.svg Ghana
Flag of India.svg India
Flag of Indonesia.svg Indonesia
Flag of the Khmer Republic.svg Khmer Republic
Flag of New Zealand.svg New Zealand
Flag of Nicaragua.svg Nicaragua
Flag of Nigeria.svg Nigeria
Flag of Norway.svg Norway
Flag of Panama.svg Panama
Flag of Paraguay.svg Paraguay
Flag of the Philippines.svg Philippines
Flag of Tanzania.svg Tanzania
United States

Civil operatorsEdit

Kenmore Air Lake Union

DHC-3 Otter on Lake Union, Seattle, WA

Flag of Canada.svg Canada
Flag of the United States.svg USA

AccidentsEdit

  • On 22 June 1994, a float equipped Dehavilland, DHC-3 Otter, N13GA, registered to and operated by Wings of Alaska, of Juneau, Alaska, crashed into the Taku Inlet, 12 miles east of Juneau. The Air Taxi flight, operating under 14 CFR Part 135, last departed the Taku Lodge located on the Taku River, and the destination was the Juneau downtown dock. Instrument meteorological conditions prevailed at the time of the accident and a company flight plan was in effect. The airplane received substantial damage. The Commercial Certificated Pilot and three passengers received serious injuries, six passengers received fatal injuries, and one passenger is missing and presumed dead.[5]
  • On 9 August 2010, a DHC-3T registered to Anchorage-based GCI crashed about 17 miles (27 km) north of Dillingham, Alaska, while en route to a private fishing lodge.[6] Five of the nine people on board were killed, including former Alaska Senator Ted Stevens. Surviving passengers included former NASA administrator Sean O'Keefe and his teenage son, both of whom sustained injuries.[7]
  • On 23 September 2011, a single-engined, turbine-powered, amphibious float-equipped de Havilland DHC-3T airplane, N361TT, sustained substantial damage during a go-around and subsequent low-altitude maneuver at Heitman Lake, about 5 miles south-southwest of Kodiak, Alaska. The airplane was being operated by Paklook Air Inc., Kodiak, as a visual flight rules (VFR) on-demand air taxi flight, when the accident occurred. Of the three people aboard, the commercial pilot sustained fatal injuries, one passenger received serious injuries, and the remaining passenger received minor injuries. Visual meteorological conditions prevailed, and company-flight following procedures were in effect. The airplane departed Old Harbor, Alaska, bound for Kodiak. A passenger on the airplane reported that during a go-around on a lake, the airplane struck a tree on the shoreline and crashed. The passenger was able to make a cellphone call, and report the accident to authorities.[8]

Specifications (Landplane)Edit

Data from Jane's Civil and Military Aircraft Upgrades 1994–95[10]

General characteristics
  • Crew: 1
  • Capacity: 9 -10 passengers
  • Length: 41 ft 10 in (12.80 m)
  • Wingspan: 58 ft 0 in (17.69 m)
  • Height: 12 ft 7 in (3.83 m)
  • Wing area: 375 sq ft (34.84 m²)
  • Empty weight: 4,431 lb (2,010 kg)
  • Max. takeoff weight: 8,000 lb (3,629 kg)
  • Powerplant: 1 × Pratt & Whitney R-1340-S1H1-G Wasp 9-cylinder air-cooled radial engine, 600 hp (448 kW)

Performance

  • Maximum speed: 160 mph (139 knots, 257 km/h)
  • Cruise speed: 121 mph (105 knots, 195 km/h) at sea level (econ cruise)
  • Stall speed: 58 mph (50 knots, 93 km/h)
  • Range: 945 mi (822 nmi, 1,520 km)
  • Service ceiling: 18,800 ft (5,730 m)
  • Rate of climb: 850 ft/min (4.3 m/s)

See alsoEdit

ReferencesEdit

Notes
  1. Rossiter 1998, p. 55.
  2. "DHC-3 Otter." Stolairus, Retrieved: February 2, 2012.
  3. Taylor 1988 p. 17.
  4. Naval Air Systems Command. "Photo of the NU-1B with the F-35B at NAS Patuxent River."
  5. NTSB Report. "NTSB Report on Wings DHC-3 Otter Crash" NTSB, 16 December 1994. Retrieved: 12 July 2013.
  6. Trimble, Stephen. "EADS executive survives Alaska air crash, but former senator killed." flightglobal.com, 10 August 2010. Retrieved: 10 August 2010.
  7. Bohrer, Becky. "Plane crashes in Alaska kills former Alaska Sen. Ted Stevens, ex-NASA chief survives." The Associated Press. via 680news.com, 10 August 2010. Retrieved: 10 August 2010.
  8. NTSB Report. "NTSB Factual Report" NTSB, 18 January 2013. Retrieved 12 July 2013.
  9. 10 killed in Soldotna plane crash, Peninsula Courier, 7 July 2013. Retrieved 7 July 2013.
  10. Michell 1994, p.24.
Bibliography
  • Hayes, Karl E. DHC-3 Otter - A History (CD-ROM). Crakaig, Killiney Hill Road, Killiney, Co. Dublin, Ireland: Karl E. Hayes Publisher, 2006. (also available via CANAV Books, Toronto)
  • Hotson, Fred W. The de Havilland Canada Story. Toronto: CANAV Books, 1983. ISBN 0-07-549483-3.
  • Michell, Simon. (ed.). Jane's Civil and Military Aircraft Upgrades 1994-95. Coulsdon, UK: Jane's Information Group, 1994. ISBN 0-7106-1208-7.
  • Milberry, Larry. Aviation In Canada. Toronto: McGraw-Hill Ryerson Ltd., 1979. ISBN 0-07-082778-8.
  • Molson, Ken M. and Harold A. Taylor. Canadian Aircraft Since 1909. Stittsville, Ontario: Canada's Wings, Inc., 1982. ISBN 0-920002-11-0.
  • Rossiter, Sean. The Immortal Beaver: The World's Greatest Bush Plane. Vancouver: Douglas & McIntyre, 1999. ISBN 1-55054-724-0.
  • Rossiter, Sean. Otter & Twin Otter: The Universal Airplanes. Vancouver: Douglas & McIntyre, 1998. ISBN 1-55054-637-6.
  • Taylor, John W.R., ed. Jane's All The World's Aircraft 1988-89. Coulsdon, UK: Jane's Defence Data, 1988. ISBN 0-7106-0867-5.
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