Hello Backcountry Pilots,
This machine could carry a guy and all his gear in style.

James
Spokane

Nice looking taildragger!

Geeze, those engine nacelles are HUGE!

Cool plane that I wouldn't mind having.

Looks like a Grumman Goose with a turbine conversion?

Might have to extend the engines forward to keep the CG in check......

saw a blue and yellow one in pendleton OR... so sweet...

N642 is a Grumman Goose that was converted with the McKinnon conversion by our old aircraft division. It uses PT-6 engines, mounted upside down to reduce water ingestion into the engine intakes during water ops.

Our maintenance folks also rebuilt another turbine goose--this one using Garrett engines--N780. That one's still flying around in South/Central America I'm told.

Last I heard, N642 was owned by a fellow in Oregon, who has it and a recip Goose, and leases both out for occasional contract work.

MTV

Kind of figured u would recognize that one Mike

mtv wrote:N642 is a Grumman Goose that was converted with the McKinnon conversion by our old aircraft division. It uses PT-6 engines, mounted upside down to reduce water ingestion into the engine intakes during water ops.

Our maintenance folks also rebuilt another turbine goose--this one using Garrett engines--N780. That one's still flying around in South/Central America I'm told.

Last I heard, N642 was owned by a fellow in Oregon, who has it and a recip Goose, and leases both out for occasional contract work.

MTV

One of the four remaining examples flew into a small grass field I was visiting in southeastern Indiana:


Pretty Sweeeet!! And yes, the engines DO appear to be upside down.


...but at 80 GPH cruise, I'm just kickin' tires here. Mathematics says 1200 miles=6hrs=almost 500 gallons of juice. OUCH! Where do they put it all?


YB

Check this out

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wardamneagle wrote:Check this out

http://www.antillesseaplanes.com/

I know what I'm getting if I win the BIG Super Lotto!

mtv wrote:N642 is a Grumman Goose that was converted with the McKinnon conversion by our old aircraft division. It uses PT-6 engines, mounted upside down to reduce water ingestion into the engine intakes during water ops.

Our maintenance folks also rebuilt another turbine goose--this one using Garrett engines--N780. That one's still flying around in South/Central America I'm told.

Last I heard, N642 was owned by a fellow in Oregon, who has it and a recip Goose, and leases both out for occasional contract work.

MTV

I'm a big fan of the Goose and especially the McKinnon conversions, so I'd like to straighten out a few facts. First of all, N642 was a "Grumman" G-21A Goose (certified under TC 654) only up until 1968 when it was converted and re-certified under a completely separate type certificate (4A24) and officially became a "McKinnon" G-21C Hybrid (i.e. turboprop conversion) but the conversion was actually done by McKinnon Enterprises Inc in Sandy, OR. If by "our old aircraft division" Mike meant either the Office of Aircraft Services (OAS) or the Fish & Wildlife Service of which he was apparently a part, that is also incorrect. McKinnon's customer in 1968 was actually the Bureau of Land Management, a different agency of the US Dept. of the Interior in Alaska. (BLM had 600 series registrations and FWS had 700 series.) He also seems to be confusing its former BLM sister ship N640 with N642. N640 is owned by a "fellow in Oregon, who has it and a recip Goose" although Teufel sold the "recip" (N48550) to Jimmy Buffett in 2009.

N640 was also a “McKinnon” turbine conversion, done per STC SA1589WE in 1967, but unlike N642, McKinnon never claimed to have completely re-certified it under TC 4A24. As far as he was concerned, N640 always remained a “Grumman” G-21A under TC 654, albeit a highly modified one with the notation “Turboprop” annotated on all of its official records. It didn’t “suddenly” become a supposed “McKinnon” G-21C ‘Hybrid’ and eventually a ‘G-21G’ until 2001 - five years after Teufel bought it in 1996 (as a “Grumman G-21A” according to the bill of sale) and ten years after Angus McKinnon died – and 30 years after McKinnon stopped converting airplanes (but that’s a whole ‘nuther story!)

Mike was correct however about N780; it was converted by FWS to have Garrett TPE331 turbines. It was actually “designed” by Theron A. Smith and Jarrett L. “Jerry” Lawhorn and “built” by FWS personnel in Anchorage. Originally, they wanted it to be certified as a McKinnon model “G-21F” under TC 4A24, but the design was never officially approved or certified as such by the FAA. Instead, FWS claimed that their conversion of N780 was a substantially modified example of a “McKinnon G-21G” conversion when in fact it was not converted by McKinnon (according to the regs pertaining to new production under FAR 21 and to FAR 45.13(a) it would be a “McKinnon G-21G” only if it was actually converted by McKinnon, but in fact the actual “builder” was FWS.) It also never actually conformed to the model G-21G type design; FWS simply converted it directly from a Grumman G-21A into a “G-21F” and then just started calling it a modified “McKinnon G-21G” in 1974 or so (they actually used the term “G-21G(STC)” but all of that’s also a whole ‘nuther story.)

Also, the PT6A series engines on this and other McKinnon Gooses are not mounted “upside-down.” The engine itself is actually mounted the same as any other; all PT6A engines have annular intakes; in other words, the intake screen encompasses the entire circumference of the back section of the engine (they are mounted kinda backwards though – that’s why the exhaust ducts are near the front with only the propeller gearbox between them and the actual prop.) The engines don’t care where the intake duct is on the cowling. Originally, McKinnon did use a default-style PT6 cowling with an intake duct on the bottom. For normal landplane ops, it is better for draining water but not so for a seaplane. In 1968 (in fact up until 1992 or so) N642 had the bottom intake cowlings and 550 shp PT6A-20 engines. When Jack Mark got a hold of it, he had his maintenance guys upgrade it to 680 shp PT6A-27 engines (actually downgraded -28s) just like a McKinnon G-21E under Section III of TC 4A24 and that is when (and why) they also added the extended dorsal fin at that time.

In any case, these photos of N642 seem to have been taken during the ferry flight by which N642 was relocated from its former home in Oshkosh, WI to its new home with Doug DeVries in Everett, WA. After it was declared surplus by BLM (OAS) in 1992 or so, it was sold to warbird collector Jack Mark of Oshkosh. I believe that Jack died in June 2007 and N642 was put up for sale soon thereafter. I did a pre-buy inspection on it in May 2008 and found many things wrong with it, including the fact that the main bulkhead between the cockpit and cabin had been cut out and opened up without a single scrap of engineering analysis, DER certification, or FAA approval.

It also turned out that during McKinnon’s original conversion and re-certification in 1968, he skipped several steps in the “G-21C” part of the conversion per Section I of TC 4A24 and he skipped ahead to the “turbine” part of the conversion per STC SA1320WE. You see, a “real” McKinnon model G-21C has four 340 hp Lycoming GSO-480-B2D6 piston engines as well as numerous structural reinforcements that raised its max gross weight from 8,000 lbs to 12,499 lbs. N642 and another McKinnon conversion done at the same time (s/n 1203 which became CF-BCI and then N660PA) lacked some of those structural reinforcements as a result of which they were certified to only 10,500 lbs – and because they were nominally McKinnon models G-21C that did not “conform” to their approved or properly modified type designs, they were not technically “airworthy” from 1968 on!

The new owner plans to spend the next several years restoring it – and he’ll have his hands full with a very big job.

Good info, thanks. Makes sence, the RGB & accessory drive wouldn't scavenge oil very well if it's simply flipped upside-down. Did the original cowl have an inertial separator, or were the engines high enough that it wasnt needed?

My favorite show http://www.goldmonkey.com/
The star of the show IS a Grumman Goose. Netflicks has all the DVD's. I heard the main aircraft in the show ended up in Seattle on Lake Union at Chrysler Air. Anyone know more about that?

L-19,
I've seen blueprints for an inertial separator (aka ice vane) in the inlet duct for the "bottom scoop" cowlings for the McKinnon turbine conversions but I don't know if it was actually used on the final installation or not. It may have simply been an idea that they explored at the time and the original installation apparently shared some engineering with the turbine conversion done on two "A" model Gooses by Alaska Coastal-Ellis Airlines (N95431, s/n 1164 and N4773C, s/n B-52.) There is also some evidence that engineering data for the PT6 engine installations were also shared with (or possibly by) Saunders who developed the ST-27 twin-turbine conversion of the old four-engine de Havilland Heron.

Unlike the McKinnon installations based on the "clean wing" theories of Alberto Alvarez-Calderon (a Stanford-educated aerodynamicist who was originally from Peru) which moved the engines inboard almost right up against the sides of the fuselage (to eliminate the turbulent airflow across the inboard wing stub between the fuselage and the engine nacelle), the ACE turbines mounted the PT6A engines directly on the existing Grumman firewalls and nacelles. With the original Grumman windshields and noses, the ACE turbine Gooses looked somewhat anachronistic compared to the McKinnon conversions which all had McKinnon’s 1-pc wraparound windshield, fiberglass “radar” nose, and retractable wingtip float modifications too.

The first ACE turbine Goose, N95431, still retained its original fixed wing floats at the time. It utilized two PT6A-6A engines that were rated at 550 shp for take-off but only 500 shp for continuous operation. When N4773C was converted some months afterward, it already had the McKinnon wingtip float mod and they used PT6A-20 engines (rated at 550 shp for all operations) just like McKinnon originally did. I’ve heard that N95431 was later upgraded to the -20s as well, but both ACE turbine Gooses were eventually restored to have R-985 radials again – and both are essentially still “airworthy” although s/n 1164, now as VH-MBA in Australia, is rumored to be in storage. Serial no. B-52 is now N42GL, owned by Chuck Greenhill in Kenosha, WI.

Regardless of all of that, the issue of the inertial separators in the bottom scoop cowlings is now moot; none still exist.

DavidB.,
There were two Gooses used to film Tales of the Gold Monkey, one of which was flyable and did all of the actual flying sequences, and the other was used as a static set piece on the Universal backlot. I suspect that it was really just an old airframe salvaged after one of the many crashes that occurred in the LA area during the times that Gooses were used on the Catalina Island run from Long Beach. That static set piece has never been properly identified; it was later salvaged and sold to the Cradle of Aviation Museum on Long Island, NY. They “restored” it for display only and it is currently painted blue and silver with “Pan American Airways” markings and the registration “NC16913” (which was actually s/n 1004) but there is no evidence that it was actually that particular Goose, which supposedly ended up in Argentina. Cradle of Aviation has occasionally mistakenly identified their static Goose as the other one, the one that was actually “flyable” during the filming of TOGM.

The “flyable” Goose was N327, s/n 1051, which was later operated by Jim Chrysler on Lake Union in Seattle. It was also later owned by current McKinnon G-21G Turbo Goose owner Bob Redner of West Bloomfield, MI. N327 crashed near Penn Yan, NY on Feb. 15, 2005. It was owned by Jetcraft, Inc. of Durham, NC at the time but it was being operated by two guys who owned Penn Yan Aero. They were practicing single-engine operations in the pattern when they lost power and control and pancaked it into the ground. It caught fire and basically burned everything except for the nose and the wingtips. The wreck of N327 is now owned by a guy in Pittsford, NY (a suburb of Rochester) who has it in his backyard and plans to rebuild it all by himself. Since buying N327, he has also bought the wrecks of N1048V (s/n B-46) and N741 (B-97) to use as sources of parts to restore N327.

A third Goose was actually the first one that was intended to be used to film TOGM, but it crashed at sea in the Gulf of Alaska on Feb. 20, 1982 during the ferry flight to take it to California. It was Red Dodge’s N2845D, s/n B-112, and it was being flown by his son and another guy. Fortunately, they got out of it OK, but they were something like 30 miles offshore and it was many hours before they were rescued – during which the Goose stayed afloat, but it eventually sank in deep water and was lost. It was still on the FAA Registry until just recently though! (It expired just last year during the recent “clean-up” and purge of the Registry because nobody had ever bothered to actually “de-register” it.)

Thanks for the clarification, and the history of these great old machines. As you noted, the 600 series airplane conversions to turbines were funded by BLM, and the work was actually done by McKinnon. I'm not sure if those Gooses were originally FWS airplanes prior to that, perhaps you know. All the FWS Grummans, I believe came from military surplus. Tom Wardleigh had some great stories about picking those airplanes up at a Naval base back on the east coast and flying them to AK.

OAS came into being somewhere around 1970, and "absorbed" the entire Fish and Wildlife aircraft operation, and OAS then re-allocated airplanes to various agencies. I didn't arrive up there till 1975, so I missed much of that "transition".

The Grumman Widgeon that Steve Harvey owns and flies today in Kodiak was an old FWS airplane that was surplused back when they got rid of all the Widgeons. I believe it was N744 when it worked for FWS.

You're right that the FWS Aircraft Division did a lot of "undocumented" work on airplanes. Then again, they operated them as "public aircraft" so at least in those days, certifications were not important. They built up some interesting airplanes in those days, some of which were pretty good airplanes. There were some Stinson Gull Wing conversions that used fuselages from one model and wings from another, as well as the Aleutian Goose, which was destroyed recently in an accident in the Middle East. Our Super Cubs had some interesting modifications as well, many of which later became blessed with actual paperwork.

Thanks again for the details of these great old airplanes.

MTV

Did anyone else notice the fuel burn numbers? Awesome bird though! I think you could live in that thing. Ultimate traveling RV right there.

mtv wrote:You're right that the FWS Aircraft Division did a lot of "undocumented" work on airplanes. Then again, they operated them as "public aircraft" so at least in those days, certifications were not important....

MTV

Yeah, I also figured that they were eligible to have been operated as "public use" aircraft and as such would have been exempt from most if not all FAA requirements. So, if the formal or official certifications were not important or needed for those government agencies to operate those aircraft, especially up in the wilds of Alaska where nobody gave a damn, why did they bother in the first place? They seem to have just "pretended" to follow the applicable FAA rules and regulations (making entries in maintenance logbooks, filling out FAA Forms 337 for mods that in some cases really weren't approved, and making applications for "Standard" certificates of airworthiness that at best probably should have been "Experimental" instead) and so forth. Then later, they surplused those improperly documented aircraft and sold them to unsuspecting private owners who literally had no clue what they were getting into - and who were techically responsible and held accountable by the FAA (in theory anyway) for insuring that their aircraft were airworthy.

That whole discussion really puts into stark contrast the subject of "airworthiness" and the related issue of conformity to type design. The formal definition of "airworthy" has been codified in the FARs only for the past six years or so - FAR 3.5(a) was implemented Sept. 16, 2005, but unofficially speaking, the exact same definition had already been around for many years prior to that in various FAA advisory circulars and orders, etc. Even so, many people still don't understand its meaning or appreciate its consequences. The idea that an aircraft "built" by an approved "manufacturer" did not actually conform to its own nominal type design and was technically "unairworthy" for the past 43 years as a result is just too much for most people to wrap their head around...but that is exactly what happened in the case of N642 after it was re-certified as a "McKinnon G-21C" in 1968.

Going on 10 years later, here's an update....
turbine Goose N642 is alive & well and living in the Puget Sound area.
I've seen it come into Jefferson County airport 0S9 a number of times recently.
I understand it went through an extensive rebuild process not long ago,
in any event it's looking great!

The 200 MPH cruise is kind of a mind blower (along with the rest of it), faster than I would have thought, wow.

courierguy wrote:The 200 MPH cruise is kind of a mind blower (along with the rest of it), faster than I would have thought, wow.

It’s the paint job that makes it go that fast.