Grumman G-21 Goose

The Grumman G-21 Goose was an amphibious aircraft designed by Grumman to serve as an eight-seat "commuter" aircraft for businessmen in the Long Island area. The Goose was Grumman’s first monoplane to fly, its first twin-engined aircraft, and its first aircraft to enter commercial airline service. During World War II, the Goose became an effective transport for the US military (including the United States Coast Guard), as well as serving with many other air forces. During hostilities, the Goose took on an increasing number of combat and training roles. The adaptable transport continued in postwar use.

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 amphibian transport. Grumman’s typically rugged engineering produced a high-wing monoplane of almost all-metal construction&mdash;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 hp 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
There were a number of modifications of the Goose, but the most numerous were those by McKinnon Enterprises of Sandy, Oregon, which had twenty-one supplemental type certificates (STCs) for modifying G-21 series aircraft and which also manufactured four different conversions that were re-certified 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-centimeter) extension in the nose section of the aircraft in front of the cockpit, and 12-inch (30-centimeter) 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 re-converted 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 re-certified 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 that they were simultaneously re-certified as models G-21C under TC 4A24, Section I, and as turbines per STC SA1320WE. However, it appears that they lacked some of the internal structural reinforcements that were part of the model G-21C design and that 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 lbs. 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, was 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 re-certified as a model G-21E and it was, in fact, equipped with the more powerful PT6A-27 engines.

The final McKinnon variant was the G-21G, which was approved by the FAA on August 29, 1969 under Section IV of TC no. 4A24. The G-21G combined 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. As well as being marketed to small air carriers, the G-21 was also promoted as a military transport. In 1938, the U.S. Army Air Force 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 amphibian was soon adopted by the Coast Guard and, during World War II, it also served with the RCAF in the transport, reconnaissance, rescue and training roles. The G.21 was used for air-sea rescue duties by the Royal Air Force (RAF). The RAF, in a common naming convention with all of its aircraft, designated the type as "Goose."

On returning to civilian service, after the war, the Goose found continued commercial use in locations from the wilderness of Alaska to the sunny climes of Catalina.

A total of 345 were built, with about 30 known to still be airworthy today (although approximately 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
 * Original production version, powered by two 450 hp (336 kW) Pratt & Whitney Wasp Junior SB engines, 7,500 lb (3,400 kg) gross weight. Six passengers. Twelve built, all converted to G-21A standards.


 * G-21A
 * Increased gross weight (8,000 lb (3,636 kg)). Thirty built.


 * G-21B
 * Export coastal patrol flying boat. Armed with .30 in machine gun in bow and dorsal hatches and two 100 lb (45 kg) bombs underwing. Twelve built for Portuguese Naval Aviation.


 * G-21C
 * Conversion by McKinnon Enterprises, 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 kh) as result of internal structural reinforcements. Two converted as piston-powered models G-21C (serial nos. 1201 and 1202) in 1958-1959. Two other airframes subsequently 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.) The 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 further converted by McKinnon with 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 re-certification 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 a McKinnon “Turboprop Goose.”


 * G-21E
 * Fully-certified new model 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 12,499 lb model G-21C. 10,500 lb (4,763 kg) gross weight. One converted (serial no. 1211.)


 * G-21F
 * Conversion by Fish & Wildlife Service in Alaska (using McKinnon engineering data) with 715 shp (533 kW) Garrett TPE331-2UA-203D turboprops. One converted but the FWS model “G-21F” was never approved by the FAA and the one example that was built was inexplicably re-certified 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
 * Final McKinnon conversion also fully certified as a new model with 680 shp (507 kW) PT6A-27 engines, 586 US gal. of fuel, and 12,500 lb gross weight. Two converted (serial nos. 1205 and 1226.)


 * XJ3F-1
 * Prototype eight seat utility amphibian for U.S. Navy. One built 1938.


 * JRF-1
 * Production version of XJ3F-1. Five built for U.S. Navy.


 * JRF-1A
 * Similar to JRF-1, but with target towing gear and camera hatch added. Five built for U.S. Navy.


 * JRF-2
 * Version for United States Coast Guard, with provision for carrying stretchers. Seven built.


 * JRF-3
 * Similar to JRF-2, but fitted with autopilot and deicing boots on wing leading edge to aid operations in Arctic. Three built for Coast Guard.


 * JRF-4
 * Similar to JRF-1A, but could carry two depth bombs under wing. Ten built for U.S. Navy.


 * JRF-5
 * Major production version, incorporating bomb racks from JRF-4, target towing and camera gear from JRF-1A and de-icing gear from JRF-3; 184 built. In 1953, a modified JRF-5 was used to test the landing and takeoff characteristics of hydro-skis for the U.S. Navy.


 * JRF-5G
 * 24 JRF-5 transferred to US Coast Guard.


 * JRF-6B
 * Navigation trainer purchased for supply under Lend-Lease. 50 built.


 * OA-9
 * Transport and air-sea rescue amphibian for United States Army Air Forces. Twenty-six ordered in 1938, supplemented by five JRF-6Bs carrying the same designation.


 * OA-13A
 * Designation given to three G-21As impressed by USAAF.


 * OA-13B
 * Two JRF-5s transferred to USAAF.


 * Goose Mk I
 * British designation for three JRF-5s supplied to the Fleet Air Arm.


 * Goose Mk IA
 * British designation for 44 JRF-6Bs supplied under Lend Lease and used for Observer training by 749 Naval Air Squadron in Trinidad.


 * Goose Mk II
 * British designation for two JRF-5s used as staff transports by British Air Commission in United States and Canada.

Military operators

 * Royal Australian Air Force
 * Six aircraft were used by No. 1 Air Ambulance Unit RAAF in Mediterranean.
 * 🇨🇦 Canada
 * Royal Canadian Air Force
 * Japan Maritime Self-Defense Force
 * Paraguayan Naval Aviation
 * Peruvian Air Force
 * Swedish Air Force
 * 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
 * Peruvian Air Force
 * Swedish Air Force
 * 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
 * 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



 * Asiatic Petroleum
 * British Guiana
 * British Guiana Airways
 * Air BC
 * Almon Landair Ltd
 * European Coastal Airways
 * H.J. O'Connell Supplies
 * Oakley Air Ltd Canada
 * Pacific Coastal Airlines
 * Sioux Narrows Airways
 * West Coast Air Services
 * Dutch East Indies
 * Koninklijke Nederlandsch-Indische Luchtvaart Maatschappij
 * Yaukuve Resort
 * Loftleiðir
 * Mount Cook Airline
 * Sea Bee Air
 * Loftleiðir
 * Mount Cook Airline
 * Sea Bee Air
 * Mount Cook Airline
 * Sea Bee Air
 * 🇺🇸 United States
 * 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

 * 13 March 1947: 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 4 other passengers were rescued by a boat after they evacuated the plane. 3 passengers could not evacuate the plane and went down with it under water. One of the passengers rescued did not survive. The pilot and 3 passengers survived. 4 passengers were killed.


 * 21 August 1958: N720 crashed in the Brooks Range, near the upper Ivishak River, in Alaska, killing U.S. Fish & Wildlife Agents Clarence J. Rhode, Stanley Fredericksen, and Clarence's son Jack. The crash site wasn't 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 US Virgin Islands when it crashed into the ocean due to engine failure. He and three passengers 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 during a flight from Vancouver International Airport to Toba Inlet, BC. The aircraft exploded into a mass of burning wreckage according to the lone survivor. This person was rescued up by the Coast Guard on South Thormanby Island off British Columbia's Sunshine Coast. 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 & Wildlife Service in Alaska, who originally intended it to be re-certified as a model G-21F, but that design was never formally approved as such by the FAA.