Grumman G 21 Goose

Design and development

In 1936, a group of wealthy residents of Long Island, including E. Roland Harriman, approached Grumman and commissioned an aircraft that they could use to fly to New York City. In response, the Grumman Model G-21 was designed as a light amphibious transport. Grumman produced a high-wing monoplane of almost all-metal construction—the trailing half of the main wing and all of the flight control surfaces except for the flaps were fabric-covered. It was powered by two 450 horsepower (340 kW) Pratt & Whitney R-985 Wasp Junior nine-cylinder, air-cooled, radial engines mounted on the leading edges of the wings. The deep fuselage served also as a hull and was equipped with hand-cranked retractable landing gear. First flight of the prototype took place on May 29, 1937.

The fuselage also proved versatile, as it provided generous interior space that allowed fitting for either a transport or luxury airliner role. Having an amphibious configuration also allowed the G-21 to go just about anywhere, and plans were made to market it as an amphibian airliner.

Modifications

A number of modifications were made for the Goose, but the most numerous are those by McKinnon Enterprises of Sandy, Oregon, which holds 21 supplemental type certificates (STCs) for modifying G-21-series aircraft and which also manufactured four different conversions that were recertified under a separate FAA type certificate (TC no. 4A24) as brand-new "McKinnon" airplanes. The first was the McKinnon model G-21C which involved replacing the original R-985 radial engines with four Lycoming GSO-480-B2D6 piston engines. It was approved under TC 4A24 on November 7, 1958, and two examples were built in 1958-1959.

The second McKinnon conversion was the model G-21D, which differed from the G-21C only by the insertion of a 36-inch (91-cm) extension in the nose section of the aircraft in front of the cockpit, and 12-inch (30-cm) extensions that were added to the horizontal stabilizers and elevators. The extended nose of the G-21D was distinguishable by the addition of two new windows on each side, and it housed four additional passenger seats. Only one G-21D was built and it was actually reconverted from the first G-21C. When later further converted to turbine engines, it was nicknamed "Turboprop Goose".

After the turbine conversion of the G-21D, McKinnon developed an STC (SA1589WE) to install the same 550-shp Pratt & Whitney Canada PT6A-20 engines on Grumman G-21A aircraft that were still certified under the original TC no. 654. Two G-21A aircraft were modified as “Hybrid” turbine conversions, one by Marshall of Cambridge in the UK (using McKinnon STC kits shipped over from Oregon) and one belonging to the Bureau of Land Management (an agency of the US Department of the Interior in Alaska) being modified by McKinnon in 1967. Because they also had many other McKinnon features installed on them using some of its STCs, these aircraft were later confused with similar but subsequent McKinnon turbine conversions and model G-21E aircraft, but they actually remained “Grumman G-21A” aircraft under TC no. 654; they were never officially recertified under McKinnon’s TC 4A24.

In addition to the two G-21A “Hybrid” turbine conversions, McKinnon converted two other G-21A aircraft in 1968 to a turbine configuration, claiming they were simultaneously recertified as models G-21C under TC 4A24, Section I, and as turbines per STC SA1320WE. However, they apparently lacked some of the internal structural reinforcements that were part of the model G-21C design and were unrelated to the turbine engine transplant from the four Lycoming GSO-480-series piston engines, as a result of which, they were certified to operate up to a maximum gross weight of only 10,500 lb. McKinnon dubbed these aircraft model G-21C “Hybrids”, but one year after they were built, their configuration was approved by the FAA as a whole new model under TC 4A24.

The third McKinnon model, the G-21E, is based on the previous G-21C “Hybrid” conversions. It was initially certified with the same two 550-shp PT6A-20 turboprops used on the G-21D turbine conversion, but later, after approval of the model G-21G, 680-shp (507-kW) Pratt & Whitney Canada PT6A-27 engines were approved as an option on the G-21E. Only one example was ever actually built and recertified as a model G-21E, and it was, in fact, equipped with the more powerful PT6A-27 engines.

The final McKinnon variant is the G-21G, which was approved by the FAA on August 29, 1969, under Section IV of TC no. 4A24. The G-21G combines all of the structural reinforcements and 12,500-lb gross weight of the earlier G-21C and D models, as well as their other features such as the “radar” nose, the “wraparound” windshield, retractable wingtip floats, and “picture” cabin windows, with the more powerful PT6A-27 turbine engines and other minor details to produce the ultimate McKinnon Goose conversion.

New production

In November 2007, Antilles Seaplanes of Gibsonville, North Carolina, announced it was restarting production of the turbine-powered McKinnon G-21G Turbo Goose variant, now identified as the Antilles G-21G Super Goose. Pratt & Whitney Canada PT6A-34 turboprops flat-rated to 680 shp (507 kW) would have replaced the original PT6A-27 engines, and the airframe systems and especially the avionics (aviation electronics – i.e. radios and navigation systems) would have been updated with state-of-the-art “glass panel” instrumentation and cockpit displays. However, as of 2009, Antilles Seaplanes' manufacturing center has been foreclosed and sold at auction. The current fate of new Goose production is currently unknown.

Operational history

Envisioned as corporate or private "flying yachts" for Manhattan millionaires, initial production models normally carried two to three passengers and had a bar and small toilet installed. In addition to being marketed to small air carriers, the G-21 was also promoted as a military transport. In 1938, the U.S. Army Air Corps purchased the type as the OA-9 (later, in the war years, examples impressed from civilian ownership were designated the OA-13A). The most numerous of the military versions were the United States Navy variants, designated the JRF.

The amphibious aircraft was also adopted by the Coast Guard and, during World War II, served with the Royal Canadian Air Force in the transport, reconnaissance, rescue, and training roles. The G-21 was used for air-sea rescue duties by the Royal Air Force, which, in a common naming convention with all of its aircraft, designated the type as "Goose".

After the war, the Goose found continued commercial use in locations from Alaska to Catalina and the Caribbean.

A total of 345 were built, with about 30 known to still be airworthy today (although around 60 are still on various civil registries, many of them are known to have crashed or been otherwise destroyed), most being in private ownership, some of them operating in modified forms.

Variants

G-21

The original production version, these were powered by two 450-hp (336-kW) Pratt & Whitney Wasp Junior SB engines, at 7,500 lb (3,400 kg) gross weight, with six passengers, and 12 were built, all converted to G-21A standards.

G-21A

Increased in gross weight (8,000 lb (3,636 kg)), 30 of these were built.

G-21B

Built as export coastal patrol flying boats armed with .30 cal machine gun in bow and dorsal hatches and two 100-lb (45-kg) bombs underwing, 12 were built for Portuguese Naval Aviation.

G-21C

Conversion by McKinnon Enterprises, these were re-engined with four 340-hp (254-kW) Lycoming GSO-480-B2D6 air-cooled, geared, and supercharged flat-six engines and fitted with retractable wingtip floats, a fiberglass “radar” nose, a one-piece “wraparound” windshield, and “picture” (enlarged) cabin windows; gross weight increased to 12,499 lb (5,669 kg) as result of internal structural reinforcements. Two were converted as piston-powered models G-21C (serial nos. 1201 and 1202) in 1958-1959, and two other airframes subsequently were converted in 1968, but with two 550-shp (579-eshp, 432-kW) Pratt & Whitney Canada PT6A-20 turboprops per STC SA1320WE as G-21C “Hybrids” (serial nos. 1203 and 1204). Two G-21C “Hybrids” were actually identical to the later 10,500-lb model G-21E, but they were never certified as such.

G-21D

One G-21C was further converted by McKinnon with an extended bow section marked by two extra windows on each side and accommodating another four passengers (serial no. changed from 1201 to 1251 in conjunction with recertification as model G-21D in June 1960.) In 1966, it was re-engined with two 550-shp (579-eshp, 432-kW) PT6A-20 turboprops and fitted with revised Alvarez-Calderon electric flaps in accordance with STC SA1320WE, retaining the G-21D designation, but subsequently identified as the McKinnon “Turboprop Goose”.

G-21E

A fully-certified new model, it was based on simplified turbine conversion of McKinnon model G-21C, with 550-shp PT6A-20 engines (680-shp Pratt & Whitney Canada PT6A-27 engines optional) and more fuel, but without all of the structural reinforcements of the G-21C. at 10,500 lb (4,763 kg) gross weight. One was converted (serial no. 1211).

G-21F

A conversion by Fish and Wildlife Service in Alaska (using McKinnon engineering data) with 715-shp (533-kW) Garrett TPE331-2UA-203D turboprops, one was converted, but the FWS model “G-21F” was never approved by the FAA and the one example built was inexplicably recertified as a supposedly modified McKinnon G-21G in spite of the fact that it was not built by McKinnon nor ever conformed to the model G-21G type design.

G-21G

The final McKinnon conversion also was fully certified as a new model with 680-shp PT6A-27 engines, 586 US gal of fuel, and 12,500 lb gross weight. Two were converted (serial nos. 1205 and 1226).

Kaman K-16B

An experimental tilt wing aircraft, it used the fuselage of a JRF-5 and was powered by two General Electric YT58-GE-2A engines; one was built but unflown.

XJ3F-1

The prototype eight-seat utility amphibious plane, it was built for the U.S. Navy; one was built in 1938.

JRF-1

A production version of XJ3F-1, five were built for the U.S. Navy.

JRF-1A

Similar to the JRF-1, but with target towing gear and camera hatch added, these five were built for the U.S. Navy.

JRF-2

A version for the U.S. Coast Guard, these had provisions for carrying stretchers; seven were built.

JRF-3

Similar to the JRF-2, these were fitted with autopilot and deicing boots on the wing leading edges to aid operations in Arctic. Three were built for the Coast Guard.

JRF-4

Similar to the JRF-1A, these could carry two depth bombs under wing. Ten were built for the Navy.

JRF-5

A major production version, these incorporated bomb racks from the JRF-4, target towing and camera gear from the JRF-1A, and deicing gear from JRF-3; 184 were built. In 1953, a modified JRF-5 was used to test the landing and takeoff characteristics of hydroskis for the U.S. Navy.

JRF-5G

These 24 JRF-5s were transferred to the US Coast Guard.

JRF-6B

A navigation trainer, these were purchased for supply under Lend-Lease; 50 were built.

OA-9

As transport and air-sea rescue for the United States Army Air Forces, 26 were ordered in 1938, supplemented by five JRF-6Bs carrying the same designation.

OA-13A

This designation was given to three G-21As impressed by the USAAF.

OA-13B

Two JRF-5s were transferred to the USAAF.

Goose Mk I

The British designation for three JRF-5s, these were supplied to the Fleet Air Arm.

Goose Mk IA

The British designation for 44 JRF-6Bs, these were supplied under Lend Lease and used for observer training by the 749 Naval Air Squadron in Trinidad.

Goose Mk II

The British designation for two JRF-5s, these were used as staff transports by British Air Commission in the United States and Canada.

Military operators

 Argentina

Argentine Naval Aviation

 Australia

Royal Australian Air Force

Six aircraft were used by No. 1 Air Ambulance Unit RAAF in the Mediterranean.

 Bolivia

 Brazil

 Canada

Royal Canadian Air Force

 Cuba

 France

 Honduras

 Japan

Japan Maritime Self-Defense Force

 Paraguay

Paraguayan Naval Aviation

 Peru

Peruvian Air Force

 Portugal

 Sweden

Swedish Air Force

 United Kingdom

Royal Air Force (several impressed examples by 24 Squadron and ATA)

Royal Navy (44 Lend Lease examples)

 United States

United States Army Air Corps

United States Army Air Forces

United States Navy

United States Coast Guard

Governmental operators

 United States

The United States Fish and Wildlife Service and the Bureau of Land Management each operated several G-21 aircraft.

 Canada

Royal Canadian Mounted Police

Civil operators

 Australia

Asiatic Petroleum

 British Guiana

British Guiana Airways

 Canada

Pacific Coastal Airlines

 Croatia

European Coastal Airlines

 Dutch East Indies

Koninklijke Nederlandsch-Indische Luchtvaart Maatschappij

 Fiji

Yaukuve Resort

 Iceland

Loftleiðir

 New Zealand

Mount Cook Airline

Sea Bee Air

 Norway

 United States

Alaska Airlines - Alaska Airlines called their turboprop-powered aircraft the "Turbo Goose" propjet. The airline also operated the piston-powered version, as well.

Alaska Coastal Airlines

Alaska Coastal-Ellis Airlines

Alaska Island Air

Alaska Fish and Game

Amphib. Inc.

Antilles Air Boats

Avalon Air Transport

Catalina Air

Catalina Channel Airlines

Chevron of California

Devcon Construction

Flight Data Inc.

Ford Motor Co.

Gulf Oil

Kodiak Airways

Kodiak Western

North Coast Aero

Ozark Management

Pan Air

PenAir

Reeve Aleutian Airways

SouthEast Skyways

Superior Oil

Sun Oil Co. (Sunoco)

Teufel Nurseries

The Texas Company (Texaco)

Tuthill Corporation

Virgin Islands Seaplane Shuttle

Webber Airlines

Accidents and incidents

19 November 1943

Grumman JRF-2 of Port Heiden, Alaska {USCG}, crashed with three crewmen and one passenger missing. It was found in 1987.

13 March 1947

A Grumman JRF-6B of Loftleiðir with seven passengers and a pilot crashed immediately after takeoff on Hvammsfjordur by the town of Budardalur in Iceland. The pilot and four other passengers were rescued by a boat after they evacuated the plane. Three passengers could not evacuate the plane and went down with it under water. One of the passengers rescued did not survive. The pilot and three passengers survived; four passengers were killed.

21 August 1958

N720 crashed in the Brooks Range, near the upper Ivishak River, in Alaska, killing U.S. Fish and Wildlife Agents Clarence J. Rhode and Stanley Fredericksen, and Clarence's son Jack. The crash site was not found until August 23, 1979.

27 January 1961

A JRF-5 of the French Navy crashed, killing Admiral Pierre Ponchardier and five others. This accident led the French Navy to retire all of their Grumman JRF-5 Gooses in the spring of 1961.

22 June 1972

N1513V of Reeve Aleutian Airways was written off at False Pass, Alaska.

2 September 1978

Charles F. Blair, Jr., former Naval Air Transport Service and Pan American Airways pilot and husband to actress Maureen O'Hara, was flying a Grumman Goose that belonged to his company, Antilles Air Boats, from St. Croix to St. Thomas in the U.S. Virgin Islands when it crashed into the ocean due to failure of the left engine. Three passengers and he were killed; seven passengers were severely injured.

3 August 2008

A Grumman Goose of Pacific Coastal Airlines with seven passengers and crew crashed during a flight from Port Hardy to Chamiss Bay. The aircraft was completely destroyed by a fire. There were only two survivors.

16 November 2008

A Grumman Goose of Pacific Coastal Airlines with eight passengers and crew crashed on South Thormanby Island near Sechelt off British Columbia's Sunshine Coast in bad weather during a flight from Vancouver International Airport to Toba Inlet, BC. Only one passenger survived. The company resumed floatplane operations on November 19, 2008.

27 February 2011

A turbine Goose, N221AG, crashed in the United Arab Emirates when it veered immediately after takeoff. Although registered in the US as a McKinnon G-21G, the aircraft was not an actual McKinnon conversion; it was instead actually designed and built by the Fish and Wildlife Service in Alaska, which originally intended it to be recertified as a model G-21F, but that design was never formally approved as such by the FAA.

17 June 2014

A Grumman G-21A Goose lost control in a snowstorm over the Montana/Idaho border and crashed into the parking lot of the Lost Trail Ski Area near the summit of Lost Trail Pass, subsequently catching fire. The plane was completely destroyed, and the pilot, who was the only occupant of the plane, was killed.

Specifications (JRF-5 Goose)

Data from United States Navy Aircraft since 1911

General characteristics

Crew: one to three

Capacity: five to seven passengers

Length: 38 ft 6 in (11.74 m)

Wingspan: 49 ft 0 in (14.94 m)

Height: 16 ft 2 in (4.93 m)

Wing area: 375 ft² (34.9 m²)

Airfoil: Root: NACA 23015, Tip: NACA 23009

Empty weight: 5,425 lb (2,466 kg)

Useful load: 2,575 lb (1,170 kg)

Loaded weight: 8,000 lb (3,636 kg)

Max. takeoff weight: 8,000 lb (3,636 kg)

Powerplant: 2 × Pratt & Whitney R-985-AN-6 Wasp Junior nine-cylinder air-cooled radials, 450 hp (340 kW) each

Performance

Maximum speed: 201 mph (175 knots, 324 km/h) at 5,000 ft (1,520 m)

Cruise speed: 191 mph (166 knots, 308 km/h) at 5,000 ft (1,520 m)

Range: 640 mi (557 nmi, 1,030 km)

Service ceiling: 21,300 ft (6,494 m)

Rate of climb: 1,100 ft/min (5.6 m/s)

Wing loading: 21.3 lb/ft² (104 kg/m²)

Power/mass: 0.11 hp/lb (0.19 kW/kg)

Armament

Bombs: 2 × 325-lb depth charges or 2 × 250-lb GP bombs