de Havilland Canada DHC-3 Otter

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DHC-3 Otter

Turbine Otter in Harbour Air livery
Role	STOL utility transport
Manufacturer	de Havilland Canada
First flight	12 December 1951
Introduced	1953
Status	Active
Produced	1951-1967
Number built	466

The de Havilland Canada DHC-3 Otter is a single engined, high wing, propeller-driven, 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 plane.

Design and development

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").

Using the same overall configuration of the earlier and highly successful DHC2 Beaver, the new design incorporated a longer fuselage, greater span wings, and was much heavier. Seating in the main cabin is for 10 or 11, whereas the Beaver could seat six. Power is supplied by a 450kW (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 featured two wing mounted Pratt & Whitney Canada PT6 turboprops.

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

Operational use

A piston-engined Otter on floats

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.]

Modifications

Turbo Otter on wheel-skis

Some aircraft were converted to turbine power using a PT6A,[1] Walter 601 (manufactured in the Czech Republic),[2], or Garrett/Honeywell TPE331-10, by Texas Turbine Conversions.[3] A Polish Pezetel radial engine has also been fitted.[4]. 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-62IR radials.

Variants

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 : Otter fitted with a 494-kW (662-hp) PT6A-27 turboprop engine.

Military Operators

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

Argentina
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