An Illustrated Overview of McKinnon Gooses

An Illustrated Overview of McKinnon Gooses

N150M – 1958 McKinnon G-21C serial no. 1201 Converted from 1942 Grumman JRF-6B (G-21A) serial no. 1147 as zero-time “new” aircraft under TC 4A24 Section I in Dec. 1958, including an ACA Form 317 “Statement of Conformity” as required for Production Under Type Certificate in accordance with 14 CFR Part 21, Subpart F. It was equipped with four 340 hp Lycoming GSO-480-B2D6 geared, supercharged, piston engines and structurally reinforced to operate up to 12,499 lbs. (Photo by Craig Grisham)

Written by Dave Marion – Built for Royal Navy under Lend-Lease and operated by No. 749 Training Squadron in Piarco, Trinidad as Goose Mk. 1A serial no. FP497 with squadron codes W2-AB. Returned to US Navy in 1945 and assigned Bu. no. 66357 but surplused to Fish & Wildlife Service in Alaska as NC709 in 1946. Sold (as N709) to McKinnon in Jan. 1957. Converted under TC 4A24 between Jan. 1957 and Dec. 1958 and re-registered as N150M in conjunction with re-certification under new TC. Initially retained by McKinnon Enterprises Inc. as personal aircraft of owner and for use as a sales demonstrator.

N3459C – 1959 McKinnon G-21C serial no. 1202 Converted from 1944 Grumman JRF-5 (G-21A) serial no. B-78 as zero-time “new” aircraft under TC 4A24 Section I in Aug. 1959, including an ACA Form 317Statement of Conformity” as required for Production Under Type Certificate in accordance with 14 CFR Part 21, Subpart F. It was equipped with four 340 hp Lycoming GSO-480-B2D6 geared, supercharged, piston engines and structurally reinforced to operate up to 12,499 lbs.

Originally built as USN model JRF-5 Bu. no. 37825 but later transferred to US Coast Guard as model JRF-5G serial no. 7825. Stationed at CGAS Barbers Point, Hawaii in 1954 then sold to Honolulu Dept. of Public Instruction and put on civil registry as N5623V. Sold to McKinnon Enterprises in Dec. 1957 for four-engine G-21C conversion. Sold to Everbrite Electric Sign Company of Milwaukee, WI in March 1959 prior to completion of McKinnon conversion.

N3459C was bought back and refurbished by McKinnon in 1967 then sold to the Government of East Pakistan for use as a de facto “Air Force One”. Re-registered as AP-AUY and ferried via north Atlantic and London, across Europe and Middle East to East Pakistan in September 1967. After the Pakistani civil war in early 1970’s, East Pakistan became Bangladesh and this aircraft was re-registered there as S2-AAD. It was eventually transferred to the National Flying Club in Dhaka, but it was withdrawn from service and abandoned in early 1980’s then finally disassembled and scrapped there in 2011.

N150M – 1960 McKinnon G-21D serial no. 1251 was converted from 1958 McKinnon G-21C serial no. 1201* in June 1960 with a 36-inch extension to the nose section, installation of extra seats, and related detail changes. *Note: as of June 29, 1960 “McKinnon G-21C serial no. 1201” officially ceased to exist as such.

Starting in 1965, N150M was further modified to have Alvarez-Calderon electric flaps and two 550 shp United Aircraft of Canada Ltd (later as Pratt & Whitney Canada Ltd.) PT6A-20 turbine engines in accordance with STC no. SA1320WE. As a result of the previous structural reinforcements but with the reduction in total horsepower from 1,360 down to 1,100 shp, the maximum gross operating weight was reduced from 12,499 lbs. down to 12,200 lbs. at the time of the turbine engine conversion.

In the summer of 1968, McKinnon Enterprises Inc. completed and re-certified two turbine Goose conversions under TC 4A24 which proved to be essentially identical to two so-called G-21AHybrid” turboprops that were done in 1967 using STC no. SA1589WE and which remained certified as “Grumman” aircraft under TC 654. Unlike those previous two aircraft, McKinnon re-certified these next two conversions as his own “McKinnon” aircraft under TC 4A24. He claimed that they were simultaneously converted under TC 4A24 Section I as models “G-21C” and under STC no. SA1320WE to have a pair of 550 shp PT6A-20 turbine engines instead of the four 340 hp Lycoming piston engines nominally specified for that model by the TC.

The thing is, they actually did not conform or qualify as modelsG-21C” in numerous ways other than the obviously different engine configuration. Most importantly, they did not have all of the structural reinforcements to allow a gross weight increase to 12,499 lbs. as a model G-21C was supposed to have per TC 4A24 and the applicable master drawing list. So, just like the two previous Grumman G-21AHybrid” turboprop conversions, the two so-called McKinnon G-21CHybrid” turboprop conversions were re-certified up to a maximum gross operating weight of only 10,500 lbs.

CF-BCInominally 1968 McKinnon G-21CHybrid” turboprop serial no. 1203 was converted from 1945 Grumman JRF-5 (G-21A) serial no. B-138 in June 1968 and equipped with a pair of 550 shp PT6A-20 turbine engines, but it is unknown if it was ever claimed to be a “zero-time” new aircraft or not because it was immediately re-registered in Canada instead of being re-certified in the U. S. and none of the applicable airworthiness re-certification documents were ever filed with or archived by the FAA – and whatever records were filed with Transport Canada in 1968 were reportedly purged after it left Canada and returned to the U. S. civil registry in 1991.

Grumman JRF-5 serial no. B-138 was delivered to the U. S. Navy as Bu. no 87744 in July 1945. It was declared surplus in 1952 with a total of 956 hours time in service, then transferred to the Fish & Wildlife Service in Alaska and registered as N779. It was withdrawn from service by FWS in March 1966 and sold to a private owner, who had it re-registered as N16484. That owner had it converted with McKinnon retractable wingtip floats (STC no. SA4-682) but later changed its registration to N501M and then sold it to McKinnon in Aug. 1967. McKinnon converted it as a so-called model G-21CHybrid” turboprop and sold it to the British Columbia Division of Highways in 1968.

In 1984, C-FBCI went to Lind Air Services Ltd. in Richmond, BC and was “upgraded” with 680 shp PT6A-27 engines and otherwise as necessary supposedly to conform as a model G-21G per TC 4A24 Section IV and that model’s applicable Master Drawing List (MDL) no. MPD-90995. Because of those upgrades, for the very first time it got all of the internal structural reinforcements that it should have had all along as a model G-21C and at that point, it was for the first time eligible to be operated up to 12,500 lbs.

However, its owner at the time as well as the folks at Lind Air Services Ltd. and Transport Canada too for that matter all incorrectly assumed that those upgrades made it an actual “McKinnon” model G-21G even though McKinnon never “built” or certified it as such himself – as required for example under the aircraft identification standards set forth by the FAA under 14 CFR §45.13(a).

McKinnon serial no. 1203 after supposed “upgrade” to model G-21G configuration and having returned to the U. S. civil registry as N660PA in Alaska

In terms of a “major alteration” under Part 43 (or its equivalent in Canada) the identification of the aircraft does not change and it remains certified and otherwise identified as what it was previously – in this particular case as a McKinnon model G-21C. On the other hand, a full conversion and re-certification as a new type (converting it from a model G-21C into a new model G-21G under 14 CFR Part 21 for example) means that whoever actually performs the conversion becomes the nominal new “builder” and the aircraft should be re-identified accordingly. So, if it really became a model G-21G in 1984, then it was as a “Lind AirG-21G, because that is who “built” it as such and it was no longer a “McKinnon” because his previous conversion had been superseded by someone else’s. The identification is based on who actually does the work, not on who originated or owns the TC under which it is re-certified.

Even so, McKinnon serial no. 1203 returned to the U. S. civil registry as N660PA with Pen Air (Peninsula Airways) in Alaska in 1991 and improperly identified as a supposed “McKinnon G-21G“. After several years of service there, including in the Aleutians Islands, it disappeared during a charter flight in Aug. 1996 with a pilot and one passenger on board. Eventually a small amount of debris was found in the water west* of Dutch Harbor on the island of Unalaska and the aircraft was declared lost, but the wreck was never found. (*The official NTSB report no. ANC96FAMS1 says “south” but that contradicts most other accounts.)

N642 nominally 1968 McKinnon G-21CHybrid” turboprop serial no. 1204 was converted from 1945 Grumman JRF-5 (G-21A) serial no. B-137 in July 1968 solely on the basis of an Application for Airworthiness Certificate (FAA Form no. 305) identifying it for the very first as a model G-21C with no corroborating production or conversion documentation* whatsoever. It was equipped with a pair of new 550 shp PT6A-20 turbine engines supposedly on the basis of STC no. SA1320WE. *Unlike all previous and even subsequent Goose “conversions” done by McKinnon, no Statement of Conformity (FAA Form no. 317) was apparently filed with the FAA as required under 14 CFR Part 21, Subpart F for Production Under Type Certificate. That form is conspicuously absent from the records archived by the FAA in Oklahoma City – and of course the thing is that all of the available evidence suggests that it actually did NOT conform as a model G-21C regardless of its supposed simultaneous conversion to have two turbine engines per STC no. SA1320WE.

Grumman JRF-5 serial no. B-137 was delivered to the U. S. Navy as Bu. no. 87743 in July 1945. It was Struck Off Charge (SOC) in Sep. 1953 with only 338 hours time in service and then transferred to the Bureau of Land Management (BLM) in Alaska in Mar. 1954, at which time it went on to the civil registry as N642. It was actually BLM who sent it to McKinnon for conversion in 1968, just as they had done previously with another Goose – one of the so-called Grumman G-21AHybrid” turbine conversions that McKinnon had done in 1967.

N642 was eventually declared surplus by BLM and sold to a private owner in Oshkosh, Wisconsin in 1989. That new owner had it “upgraded” with 680 shp PT6A-27 engines per FAA approval predicated on its similarity to a McKinnon model G-21E for which such engines were already approved as an option under TC 4A24 Section III. (As far as I am concerned, it was actually a model G-21E all along – it was simply that it was converted and re-certified by McKinnon in 1968 as such a full year before the model G-21E was officially approved by the FAA and added to TC 4A24 in 1969.)

N642 is currently undergoing another conversion to a supposed 12,500 lb. model G-21G configuration by its current owner in Washington state, essentially just as was done to C-FBCI by Lind Air Services Ltd. in British Columbia in 1984. Except instead of explicitly following the official model G-21G MDL (MPD-90995) the owner of N642 seems also to be free-lancing some structural details based on the separate but unnecessary guidance of his own DER – which to me raises questions about the validity of its eventual conformity as a supposed model “G-21G”.

I also consider his project to be “illegitimate” because the current owner of the aircraft does not have permission from the current TC Holder to “build” a new model G-21G aircraft as required by 14 CFR §21.6. Also because photos posted on the project’s Facebook page clearly show that they have installed co-pilot’s “dual” brakes with reference to McKinnon drawing no. MPD-70102 – in apparent violation of 14 CFR §91.403(d) which requires them to have written permission from the owner of the applicable STC, which as far as I know, they do not.

Additionally, McKinnon drawing no. MPD-70102, which is approved for installation on a Goose as of yet only by means of STC no. SA2317WE, is approved for installation in particular only on Grumman G-21A aircraft still certified under TC 654; it is not nominally applicable to or explicitly approved for “McKinnon” G-21 series aircraft that have been converted and re-certified under TC 4A24.

N5558 (shown here during its time as ZK-ERX) – 1969 McKinnon G-21G serial no. 1205 was converted from 1944 Grumman JRF-5 (G-21A) serial no. B-62 as a “zero-time” new aircraft under TC 4A24 Section IV in Sep. 1969; documentation for which includes the aforementioned FAA Form 317Statement of Conformity” as required under 14 CFR Part 21, Subpart F. It was equipped with a pair of 680 shp PT6A-27 turbine engines and structurally reinforced and certified to operate up to 12,500 lbs.

Built for U. S. Navy as JRF-5 Bu. no. 37809 in May 1944. It served in Dakar, Senegal and Port Lyautey, Morocco before returning to NAS Norfolk, VA. Struck Off Charge (SOC) as obsolete and surplus in Feb. 1947. Sold to an unknown private owner and initially registered in the U. S. as a civilian model G-21A (as N5556N) but quickly sold to Flugfélag Íslands airline in Iceland, where it was re-registered as TF-ISR (apparently the second Goose to carry that registration after its predecessor, serial no. B-134 was extensively damaged.)

Serial no. B-62 was withdrawn from commercial service and relegated to duties as a maintenance instructional airframe in 1956. In 1967 it was sold to a new private owner back in the U. S. who had it re-registered as N5558 and in turn sold it to McKinnon Enterprises Inc. in Oct. 1967 and who eventually converted to a model G-21G in 1969. Initially kept by McKinnon as a sales demonstrator, it was forfeited to the bank by his bankruptcy in 1972, after which it was sold to the owner of a large drug store chain.

In 1980, it was sold to Sea Bee Air Ltd. in New Zealand, re-registered as ZK-ERX, and ferried “down under” via Hawaii (reportedly using extra fuel tanks that caused it to be loaded in excess of 21,000 lbs. for at least one take-off!) It spent 4 years flying mostly among the islands of Tuvalu in the South Pacific before it came back to the U. S. as a corporate aircraft registered as N77AQ and based in Ohio from 1984 until 1990. Since then, it has been with a different private owner in Portland, OR.

N70AL – 1970 McKinnon G-21G serial no. 1226 was converted from 1945 Grumman JRF-5 (G-21A) serial no. B-125 as a “zero-time” new aircraft under TC 4A24 Section IV in Mar. 1970; documentation includes the aforementioned FAA Form 317Statement of Conformity” as required under 14 CFR Part 21, Subpart F. It was equipped with a pair of 680 shp PT6A-27 turbine engines and structurally reinforced and certified to operate up to 12,500 lbs.

After many years of service in the U. S. Navy, Bu. no. 87725 was transferred to training duties with the Japanese Maritime Self-Defense Force in the 1950’s. It was retired in the early 1960’s and was the second of two such surplus Gooses bought by movie stunt pilot Tom Danaher of Wichita Falls, Texas. He kept the first one but turned around and sold this one to McKinnon in Aug. 1969. Without ever registering it as a civilian model G-21A, McKinnon converted it into his second and last model G-21G. After many years of service with two large corporate operators first in Alaska (Champion Paper) and then in Louisiana (Chevron Oil) it has passed through several private owners. It will soon be airworthy once again after an extensive restoration by its current owner in Michigan.

N121H – 1970 McKinnon G-21E serial no. 1211 was converted from 1938 Grumman G-21A serial no. 1013 as a “zero-time” new aircraft under TC 4A24 Section III in May 1970; documentation includes the aforementioned FAA Form 317Statement of Conformity” as required under 14 CFR Part 21, Subpart F. It was equipped with a pair of 680 shp PT6A-27 turbine engines per the approved option but certified to operate up to only 10,500 lbs. Incongruously, unlike every other McKinnon conversion, it never had its cabin windows enlarged and always retained the stock Grumman main window configuration.

Grumman Goose serial no. 1013 was the very first model G-21A built and certified with a gross weight of 8,000 lbs. (Serial nos. 1001 through 1012 having been built as 7,500 lb. models G-21 before they were later upgraded to model G-21A status.) It was initially sold to J. P. Bickell of Toronto, Ontario, who was the owner of the McIntyre-Porcupine Mining Co. It was registered in Canada as CF-BKE, but after the outbreak of war in Sep. 1939, it was sold to the Royal Canadian Air Force. The RCAF used it throughout the course of the war in various “communication” squadrons, until it was retired and transferred by disposal by the War Assets Corporation in Jan. 1945.

After a variety of owner civilian owners during the intervening years, in June 1954, it was sold to the Halliburton Oil Well and Cementing Co. of Duncan, OK and re-registered as N121H. It was Halliburton who still owned it 16 years later and sent it to McKinnon to be converted as a turbine model G-21E. Halliburton continued to operate it for another 21 years afterward, until Nov. 1991 – a total of 37 years of ownership. Unfortunately, it crashed due to pilot error during a post-restoration test flight in the Chicago area in 1995 and both pilots on board were killed.

That covers all of the Gooses ever converted and re-certified under TC no. 4A24 actually by Angus “Mac” McKinnon and his company, McKinnon Enterprises Inc. of Sandy, OR. Any other Goose that is claimed to be a “McKinnon” is not one and is probably really just an amateur-built “copy” of a McKinnon design. As long as they properly conform to the applicable type design, those “copies” can still be certified under TC 4A24, but that fact alone does not make them actual “McKinnon” aircraft. Still, in my opinion, the distinction and differences are important.

Dave Marion is the Technical Content Editor at Seaplanemagazine.com. As A&P and IA with 29 years of experience in aircraft maintenance, he is also a Commercial Pilot with Airplane, Single & Multi-Engine, and Instrument ratings. He has a BA from Colgate University in 1984 and also graduated cum laude from Embry-Riddle Aeronautical University (DAB) with a BS in Aviation Technology in 1990. He can be reached along with all of the editors via E-Mail: editor@seaplanemagazine.com

1 Comment on "An Illustrated Overview of McKinnon Gooses"

  1. Bruce Hinds | April 29, 2018 at 3:58 am |

    Hi Dave. Great article.
    I remember you’d told me about some of the history of the “Aleutian Goose” – the Garrett powered one that had supposedly been a McKinnon but wasn’t, then converted by the forest service. Can you give us the story on that one?

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