From the beginning, starting with c/n 1201 - McKinnon style!

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From the beginning, starting with c/n 1201 McKinnon style!

Postby Rajay » Sun Jul 14, 2013 9:49 pm

Shortly after the last photo above was taken in 1965, McKinnon embarked on, if not actually the most comprehensive, certainly the most significant modification or conversion of any of his various Goose aircraft.

Working in conjunction with Alaska Coastal-Ellis Airlines of Juneau, AK and Strato Engineering Co. Inc. of Burbank, CA, they developed new powerplant installations for G-21 series Goose airframes using PT6A turbine engines in the 500-550 shaft horsepower range.

Alaska Coastal-Ellis chose to keep their turbine Super Goose conversions as simple as possible and basically just grafted the new engines onto the existing nacelles and firewalls after removing the original R-985 radial engines. Their first conversion was done on N95431, Grumman G-21A Goose serial no. 1164. At that time, it still had its original arched windshield, blunt metal nose, and fixed wing floats. With the straight-mounted turbine engines jutting far in front of the original engine nacelles, it looked anachronistic for a turbine aircraft.

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McKinnon on the other hand chose to start with a “blank sheet of paper” and incorporated the “clean-wing” theories of Peruvian aerodynamicist and Stanford-trained aeronautical engineer Alberto Alvarez-Calderon.

The theory was that by moving the engine nacelles inboard right up against the sides of the fuselage and angling the engines up and outward just enough for the necessary propeller clearances, the turbulence normally produced by the interaction of the engine nacelle, inboard wing stub, and the fuselage would be virtually eliminated. It also had the effect of reducing asymmetric thrust in an engine-out emergency situation and improved airflow over the rudder and vertical stabilizer. Minimum controllable airspeed (Vmc) was actually reduced below the clean stall speed of the aircraft (Vs).

McKinnon submitted an application for a new STC to cover these mods on July 28, 1965 and in conjunction with the modifications actually made to N150M over the next 20 months or so, the FAA approved STC SA1320WE on February 16, 1967.

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In addition to the installation of a pair of 550 shp PT6A-20 turbines on either a McKinnon G-21C or G-21D in place of their “original” four 340 hp Lycoming GSO-480-B2D6 geared, supercharged, flat, piston engines, STC SA1320WE also covered the installation of a new electric flap system also designed by Prof. Alvarez-Calderon. The new flaps were hinged, strangely enough, at the trailing edge and either rotated forward up underneath the wing for storage or down and behind the wing when deployed, effectively increasing both the chord and camber of the wing – supposedly similar to but “simpler” than Fowler flaps. I can only guess at the turbulence that they must have generated as they were extended.

After hanging on to it through the course of three major conversions, McKinnon finally parted with N150M and in Dec. 1966 sold it to the Precision Valve Corporation of Yonkers, NY, although it was not actually delivered and re-registered until after the completion of its re-certification as a turbine “Hybrid” (to use McKinnon’s own vernacular) with a new CoA in February 1967.

Precision transferred it through two or three separate divisions over the next six years and in 1973 or so it was sold to Peyton Hawes, co-founder of the Payless Drugs store chain, almost all the way back “home” in the Portland, OR area. Hawes also owned at that time the first McKinnon G-21G conversion, N5558, serial no. 1205 (ex-USN JRF-5 BuAer. 37809, Grumman OEM serial no. B-62.) Only a couple of years later, presumably for that exact reason, Hawes sold N150M in a deal brokered by Angus McKinnon (at that time d/b/a McKinnon Coach Inc.) to Hal Beale of On Mark Aviation in Knoxville, TN.

I had an opportunity to meet and talk with Mr. Beale several years ago and he told me that of all of the aircraft that he had ever owned, N150MMcKinnon G-21D serial no. 1251 – was among his all-time very favorites. And mind you, this is a guy who modified Douglas A-26 Invaders into executive transports for a business and raced Grumman F8F Bearcats at Reno! He said that the turbine Goose was his “go-anywhere, land-anywhere, carry anything, no compromises” aircraft that would do whatever he needed it to do – and he was sorry that he ever sold it.

But sell it he did – and it went to the infamous Whittington brothers, Bill and Don, who were famous for racing airplanes also at Reno, cars on the Indy circuit (and they owned the Road Atlanta racetrack) and infamous for financing their racing efforts by smuggling something like 400,000 lbs. of marijuana into Florida in the 1980’s. N150M is still "currently" registered (albeit "expired") to their corporate alias Water Fowl Inc. of Ft. Lauderdale, FL but as long as 20 years ago, it was rumored to have been seized in Haiti (alternately Cuba) because of its involvement with their drug smuggling activities and subsequently scrapped. A truly ignominious end for such a unique and storied aircraft.
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From the beginning, starting with c/n 1201 McKinnon style!

Postby Rajay » Mon Jul 15, 2013 5:01 am

Just came across a "new-to-me" photo of what must be N3459C, McKinnon G-21C serial no. 1202, taken by photographer Miles Blaine in the San Diego area and which is now part of his "collection" in the archives of the San Diego Air & Space Museum. Here's the link to the photo on Flickr.com:

http://www.flickr.com/photos/sdasmarchives/8595380901/sizes/l/in/photostream/

Image

The weird thing is that the aircraft in the photo exhibits features and characteristics that I thought (per my analysis above) were unique to each of the two different McKinnon models G-21C - N150M and N3459C.

I've contacted the museum to see if they have any more information about the photo - such as where and when it was taken (I had no idea either McKinnon G-21C had ever ventured down that way) or any information about the subject airplane too.

I've pretty much decided that, even though no registration is visible in the photo, it has to be N3459C. Although it has a main accent stripe that stops short of the nose cone and still has the double-vent extended hull step just like N150M, it also has black wing leading edge (de-icer?) boots and the tunnel vent just like N3459C. Those first two features are easier to change than the last two.

I'll be curious to hear what the museum can tell me about the photo in their collection. Apparently, the photographer (Miles Blaine) died in 2009, so he can't answer any questions about it.

I did once upon a time come across an old newspaper story about an air ambulance service inaugurating it soperation and flying a four-engine Goose out of the then brand-new South Lake Tahoe airport in 1959. Also, one of the B&W photos of N150M seems to have been taken at some very sandy, desert-like airfield which could have been in the Reno or Carson City area in conjunction with such an operation - but McKinnon did not sell N150M until Dec. 1966, by which time it had been converted both as a long-nose model G-21D and with only two PT6A turbine engines per STC SA1320WE. So if an air ambulance service was using it out of Lake Tahoe in 1959, it must have been just on loan for a temporary evaluation or whatever.
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From the beginning, starting with c/n 1201 - McKinnon style!

Postby Rajay » Fri Jul 19, 2013 6:03 pm

The next two turbine Goose conversions with which McKinnon was involved have often been mistakenly identified as actual “McKinnon” aircraft supposedly re-certified under type certificate 4A24, but in fact they were not. They were never “properly” re-certified under TC 4A24 and they were never officially issued a “McKinnon” serial number – at least not actually by McKinnon (which BTW / FYI is the only way it can be done properly or with any kind of validity.)

The two aircraft in question were registered at the time as N640 and G-ASXG.

Image

N640 was Grumman G-21A “Goose” serial no. B-123 and it was owned by the Bureau of Land Management (BLM) which was – and still is for that matter – a federal agency under the U.S. Dept. of the Interior. Serial no. B-123 was originally manufactured by Grumman in April 1945 as a model JRF-5 for the U.S. Navy as Bureau of Aeronautics serial or “Bu.” no. 87729. After its transfer from the U.S. Navy to BLM sometime prior to March 1954, Grumman Goose serial no. B-123 was first registered as N640 and it was sent to Alaska.

On August 31, 1966, the BLM pilot who was flying N640 near Alegnagik, AK misjudged his approach to the glassy surface of a lake and crashed into the water. According to the accident report (ref. NTSB no. ANC67D0063*) the Goose sank in something like about 100 feet of water. Eventually it was raised and salvaged and BLM chose to have it shipped to McKinnon Enterprises Inc. in Sandy, Oregon for both repairs and conversion to new turbine engines.

*http://www.ntsb.gov/aviationquery/brief.aspx?ev_id=22441&key=0

In conjunction with the repairs that McKinnon made on N640, he also installed on it many of his STC modifications including the extended fiberglass “radar” nose, the one-piece “wrap-around” windshield, the retractable wingtip floats, and the enlarged main cabin “picture” windows. Because his existing STC SA1320WE for the installation of a pair of 550 shp PT6A-20 turbine engines was applicable to and approved for use only on his model G-21C or G-21D aircraft already converted and re-certified under TC 4A24 (which N640 was not) on April 4, 1967 McKinnon applied to the FAA for a new STC that would cover an essentially identical turbine engine installation on Grumman G-21A aircraft still certified under ATC-654 – as was N640.

On July 21, 1967 as the repairs and basic modifications to N640 were being completed, McKinnon submitted an application to the FAA for a new temporary certificate of airworthiness in the Experimental category for N640 so that it could be flight-tested in its new configuration. Just about two weeks into that flight test program, on August 5, 1967, McKinnon had a little mishap while taxiing in after landing N640 on the grass strip adjacent to his shop. According to the NTSB report (ref. SEA68D0099 – see link below) he ground-looped it while trying to troubleshoot an engine surging problem and mishandling the engine and prop controls – and the aircraft sustained substantial damage.

http://www.ntsb.gov/aviationquery/brief.aspx?ev_id=17473&key=0

By the first week of November 1967, N640 had been repaired once again and McKinnon filed an application for another temporary CoA still in the Experimental category – after which the flight test program resumed.

Finally with the completion of the flight test program, N640 received a new certificate of airworthiness in the Standard category on January 12, 1968 and McKinnon’s STC for the installation of the PT6A-20 turbine engines on legacy Grumman G-21A aircraft was approved by the FAA as STC no. SA1589WE on January 24, 1968.

Note that on the application for that Standard CoA, McKinnon specifically referenced STC SA1589WE (and not SA1320WE as later claimed by a subsequent owner of N640) and the aircraft was still officially identified as “Grumman G-21A serial no. B-123” albeit for the first time annotated with “Turboprop” but also still certified under ATC-654 in any case.
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From the beginning, starting with c/n 1201 - McKinnon style!

Postby Rajay » Sat Jul 20, 2013 9:16 pm

And for the story of G-ASXG, which was also improperly identified at some point in the past as a "McKinnon G-21C 'Hybrid' Turbo Goose" but really was never actually certified as anything other than Grumman G-21A "Goose" serial no. 1083, see its separate thread here:

http://theflyingboatforum.forumlaunch.net/viewtopic.php?f=33&t=1427

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From the beginning, starting with c/n 1201 - McKinnon style!

Postby Rajay » Tue Aug 06, 2013 2:34 am

After completing the turbine conversions of his one and only model G-21D, N150M, per STC SA1320WE in February 1967 and of N640, Grumman G-21A serial no. B-123, for its owner, the Bureau of Land Management in Alaska per STC SA1589WE in January 1968, and after supplying parts and technical data to help Marshalls of Cambridge convert G-ASXG, Grumman G-21A serial no. 1083, for the Grosvenor Estates in the UK (which was eventually completed in July 1968 also presumably per STC SA1589WE) McKinnon jumped right into two more turbine Goose conversions in early 1968.

Contrary to any of the previous turbine conversions, McKinnon claimed to have converted and re-certified these next two turbine Gooses as his own model “G-21C” aircraft under TC 4A24 Section I, supposedly simultaneously modified with turbine engines (still 550 shp PT6A-20 series engines) per STC SA1320WE. However, exactly like all of the previous turbine Goose conversions, they still were not actually “conforming” model G-21C aircraft, literally regardless of the turbine engine modification. The only actual difference between these two aircraft and the two previous Grumman G-21AHybrid” turboprops (N640 and G-ASXG) was the fact that McKinnon did officially claim them as his own products under TC 4A24.

The facts of the matter are such that he should not have done so because when he was done with them both in July 1968, they did not conform as 12,499 lb. McKinnon models “G-21C” – but they did conform as Grumman G-21AHybrid” turboprop conversions per STC SA1589WE - and as the later McKinnon model G-21E, the type design for which was not approved by the FAA and certified under TC 4A24 Section III until a year later in July 1969 - all of which were re-certified up to only 10,500 lbs because they all lacked the same internal structural reinforcements that allowed the “real” models G-21C as well as the models G-21D and G-21G to be operated all the way up to the 12,500 lbs.

Note: the only difference between STC SA1589WE and STC SA1320WE is on what they are eligible or approved to be installed; the actual installations of the two 550 shp PT6A-20 turbine engines are in either case identical. STC SA1589WE installs them on legacy Grumman G-21A series aircraft still certified under ATC-654 and STC SA1320WE installs them on McKinnon G-21C or G-21D series aircraft supposedly already previously converted and re-certified by McKinnon under TC 4A24.
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From the beginning, starting with c/n 1201 - McKinnon style!

Postby Rajay » Tue Aug 06, 2013 3:23 am

McKinnon serial no. 1203

CF-BCI / C-FBCI / N660PA


The two so-called, but really only “faux” McKinnon G-21CHybrid” turboprop conversions were registered as CF-BCI in Canada and as N642 in the US. They were actually originally consecutive serial numbers of Grumman model JRF-5 aircraft built for the US Navy during World War II and they became, or at least they were claimed to have become - “McKinnon” aircraft with consecutive new serial numbers as well.

Grumman built JRF-5 (OEM serial no. B-138) for the US Navy as Bureau of Aeronautics serial or “Bu.” no. 87744 in July 1945. After the war, it continued to serve the Navy until being declared “surplus” and it was transferred to the Dept. of the Interior (USDI) in September 1952. USDI posted it to the Fish & Wildlife Service (FWS) in Alaska and it was given a civilian registration as a Grumman G-21A with the N-number N779. It remained with FWS in Alaska until April 6, 1966, when it was sold to Charles Walters of Spokane, WA and re-registered as N16484.

Only a month later, on May 6, 1966, its registration was changed to N501M in conjunction with an anticipated sale to McKinnon Enterprises Inc. which itself was not finalized until August 24, 1967 – more than a year later. Apparently Angus McKinnon knew that Charles Walters had it and that he wanted it, but he must not have had the money or maybe the space for it in his shop until, for one possible example, he sold N3459C (the “real” model G-21C serial no. 1202) to the government of East Pakistan (re-registered as AP-AUY) about the same time that he finally bought and paid for N501M.

The US registration for N501M was cancelled on December 19, 1967 and in July 1968, its conversion to a “Hybrid” Turbo Goose was at least nominally complete (on paper anyway) and the aircraft went to a new owner, the British Columbia Division of Highways, registered in Canada as CF-BCI, nominally “McKinnon G-21C” serial no. 1203.

CF-BCI (later as C-FBCI) was eventually sold to Air West and Jim Pattison Industries. In late 1984, it was taken to Lindair Services Ltd of Richmond, BC and supposedly “upgraded” to a model “G-21G” configuration with more powerful 680 shp PT6A-28 engines (which technically were not approved for use on a model G-21G until a revision was made to TC 4A24 in 2005 (for which reason the -28 engines used on C-FBCI were apparently “downgraded” to PT6A-27 specifications – essentially just a TIT limit lowered by only 25 degrees C.) However, it must be noted that even though they supposedly conformed C-FBCI to the model G-21G Master Drawing List (i.e. Strato Engineering Co. Inc. report no. MPD-90995) that did not make it an actual model G-21G - and it especially did not make it one supposedly built by McKinnon.

As far as I can tell, Lindair Services Ltd. had no authority to use legacy McKinnon engineering data in its “raw” form as blueprints which were approved for use only in a FAR Part 21-certified manufacturing environment – and no STC has ever been approved for that use “in the field” by a private owner or other third party (such as an MRO like Lindair Services.) They also had no right to “build” a new model “G-21G” and call it an actual “McKinnon” product, regardless of the McKinnon-produced Turbo Goose with which they started. On the other hand, C-FBCI was never a valid “McKinnon G-21C” in the first place and by supposedly conforming it as a model “G-21G” they essentially only finally conformed it according to its official identification as a model G-21C “Hybrid” turboprop.

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C-FBCI, McKinnon G-21C "Hybrid" Turbo Goose serial no. 1203 in 1991 shortly before its sale to Pen Air in Alaska - i.e. after its supposed "upgrade" to a model "G-21G" configuration by Lindair Services Ltd. in 1984. Prior to that "upgrade" it had the less powerful 550 shp PT6A-20 engines and the cowling intake scoops were on the bottom. It also did not have the extended dorsal fin until the 1984 upgrade - even though it was a mandatory feature of a McKinnon model "G-21C".
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From the beginning, starting with c/n 1201 - McKinnon style!

Postby Rajay » Tue Aug 06, 2013 3:39 am

Contrary to the note that Angus McKinnon put under Section III of TC 4A24, a “real” model G-21C modified per STC SA1320WE, albeit with “upgraded” 680 shp PT6A-27 engines instead of the nominally-specified 550 shp PT6A-20 engines, actually would be essentially “identical” to a model G-21G more so than to a model G-21E as he claimed. What he actually built and identified as G-21CHybrid” turboprops were in fact more or less identical to the later model G-21E approved under Section III, but they (serial nos. 1203 and 1204) were never really valid model G-21C aircraft in the first place; they were actually just Grumman G-21AHybrid” turboprops or McKinnon models G-21E in terms of actual conformity to a particular type design.

A highly detailed “proof” of these assertions here can be achieved by comparing the respective Master Drawing Lists (MDL) for each model, but the simpler rule of thumb by which they can be judged are the facts that both the “real” four-engine (piston) models G-21C and the later turbine models G-21G were certified up to 12,500 lbs whereas both of the Grumman G-21AHybrid” turboprop conversions (N640 and G-ASXG), the so-called McKinnon model G-21CHybrid” Turbo Gooses (C-FBCI and N642), and the McKinnon model G-21E (only one example of which was converted and officially re-certified in May 1970 – N121H) were all certified up to only 10,500 lbs.

After its supposed “upgrade” as a model “G-21G” by Lindair Services Ltd. which was signed off on October 5, 1984, C-FBCI went to Crown Forest Products in 1985. In 1991, it was re-registered to Walsten Aircraft Parts & Leasing, Inc. who ended up brokering its sale to Pen Air (Peninsula Airways) in Anchorage, AK in August 1991.

Strangely enough, according to former Pen Air Chief Pilot Fred Ball, even though it was by that time "officially" (but incorrectly and improperly) re-identified as a model “G-21G” the FAA required Pen Air to conduct and document an exhaustive flight test program in order to create a comprehensive new flight manual for the aircraft – in spite of the fact that an FAA-approved flight manual for the McKinnon model G-21G had already been created separately for the two aircraft actually manufactured and re-certified as such by McKinnon in 1969 and 1970.

In any case, re-registered as N660PA, McKinnon serial no. 1203 was operated as a Part 135 on-demand charter aircraft by Pen Air in the Aleutian Islands until August 11, 1996 when it apparently crashed at sea after picking up a harbor pilot from a ship in Anderson Bay on the island of Unalaska. Both the pilot and the passenger, the harbor pilot, were presumed to have been lost at sea as the wreck of the aircraft was never actually located.

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Also strange are the apparent contradictions noted by NTSB report no. ANC96FAMS1 which states that the airplane was lost approximately “20 miles south of Dutch Harbor” but simultaneously notes that it took off from Anderson Bay (which is actually southwest of Dutch Harbor) and then proceeded “northbound” toward Makushin Bay and Volcano Bay where witnesses claimed to have heard it “arrive in the area but not depart.” Those two bays are actually northwest of Anderson Bay and if N660PA had headed in that direction, it would have been flying away from Dutch Harbor and would have ended up distinctly west of there, not “south” as indicated in the report.

Ref. http://www.ntsb.gov/aviationquery/brief2.aspx?ev_id=20001208X06390&ntsbno=ANC96FAMS1&akey=1
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From the beginning, starting with c/n 1201 - McKinnon style!

Postby Rajay » Tue Aug 06, 2013 8:53 pm

McKinnon serial no. 1204

N642


Grumman-built JRF-5 (OEM serial no. B-137) for the US Navy as Bureau of Aeronautics serial or “Bu.” no. 87743 in July 1945. After the war, it continued to serve the Navy until being declared “surplus” and it was transferred to the Dept. of the Interior (USDI) sometime prior to March 1954. USDI posted it to the Bureau of Land Management (BLM) in Alaska and it was given a civilian registration as a model G-21A with the N-number N642. During its initial conformity and acceptance inspection for its civilian certification and registration, it was noted that it had only 382.1 hours Time In Service (TIS) as of April 1954.

In February 1962, N642 was modified with the STC SA1-439 “Goose” door (aka a “smokejumper” or cargo door) on the right side of the fuselage in place of the original emergency exit hatch. This large door was a floor-to-ceiling arrangement that was pinned into place and not hinged so that it could be removed completely in order to provide clear access into the airplane for loading cargo or out of the airplane for smokejumpers to exit it in flight.

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This photo of N642 after its conversion as “McKinnon G-21C ‘Hybrid’ Turbo Goose serial no. 1203”
shows the details of both its turbine modifications and the cargo/smokejumper door on the right
side of the fuselage. Note: the 0.25 inch thick doubler plates that had to be added to reinforce
perimeter of the larger door.

After N640 (Grumman G-21A serial no. B-123) was converted to turbine engines per STC SA1589WE and other mods by McKinnon in 1967, BLM decided to send N642 to Sandy, OR for similar modifications. In conjunction with the turbine conversion of Grumman G-21A s/n B-138 (N501M) into McKinnon G-21CHybrid” s/n 1203 (CF-BCI) N642 was converted and re-certified as McKinnon G-21CHybrid” turboprop s/n 1204 in July 1968. As part of the documentation of the conversion of N642, McKinnon filed an FAA Form 337 "Major Repair and Alteration" on which he claimed the installation of STC SA1320WE on Grumman G-21 serial no. B-137 – but that STC is not approved or eligible for installation on a Grumman model G-21 or G-21A still certified under ATC-654.

Also, unlike most if not all of his other conversions supposedly re-certified under TC 4A24, McKinnon apparently failed to file an FAA Form 317Statement of Conformity” to certify its “production” as a new model G-21C aircraft. Instead he filed just an application for a new Standard certificate of airworthiness on which he simply but without any supporting documentation re-identified it as “McKinnon G-21C” serial number “1203”. Consequently, N642 was not officially “rebuilt” or “zero-timed” as a “new” aircraft and all of its legacy Time in Service was carried over; as of July 26, 1968, that amounted to some 5,746.25 hours TIS. The fact of the matter is that even if McKinnon had filed a Form 317, it would not have been valid because N642 did not at that time and also at no time since then actually “conform” as a model G-21C aircraft, regardless of its supposed turbine conversion per STC SA1320WE.

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This photo also clearly shows that N642 was initially converted as a so-called McKinnon model “G-21C” without having the mandatory extended dorsal fin installed. That and the fact that the engine cowlings have the early-type bottom intake scoops is indicative of the installation of the 550 shp PT6A-20 turbine engines. (When a McKinnon model G-21E has the “optional” 680 shp PT6A-27 engines, it too must have the extended dorsal fin installed.)
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From the beginning, starting with c/n 1201 - McKinnon style!

Postby Rajay » Tue Aug 06, 2013 9:25 pm

After its conversion and re-certification as McKinnon G-21C serial no. 1204, N642 was sent back to Alaska and served with the Bureau of Land Management (BLM) until all USDI aircraft operations were turned over to the newly formed Office of Aircraft Services (OAS) in 1974.

Image

In 1989, OAS declared N642 to be “surplus” to their needs and on August 16, 1989, on their behalf, the General Services Administration (GSA) put out a notice of a sealed bid auction which included among other assets N642, McKinnon G-21C Turbo Goose serial no. 1204. The aircraft was listed as “ferryable” with some 12,352.5 hours TIS on it. It included two 550 shp PT6A-20 engines with some 2,469.5 (left) and 3,054.1 (right) hours TIS on them respectively and two Hartzell props with 1,727.4 hours TIS on each of them. The minimum bid was listed as $200,000.00.

On August 31, 1989, N642 was sold to John “Jack” Mark of Oshkosh, WI for $271,000.00 USD and on November 15, 1989, it was re-registered to his company, MA Inc. Apparently during this transition from a “public-use” aircraft to a privately owned and operated one, no conformity inspection of any kind was conducted by either the new owner or the FAA prior to or in conjunction with its re-certification and transfer of registration. In spite of the facts that while owned and operated by agencies of the US Dept. of the Interior N642 was not actually required to follow, obey, or be maintained in accordance with the Federal Aviation Regulations (FARs) and actually did not in fact conform to its nominal type design as a McKinnon model “G-21C” under TC 4A24, all of the incomplete and/or erroneous documentation associated with its McKinnon conversion in 1968 appears to have been taken at face value.

On June 18, 1990, Jack Mark’s mechanics installed the extended dorsal fin supposedly per STC SA4-681 and drawing no. MPD-4004. They also re-configured the engine cowlings with top-mounted intake scoops in accordance with manufacturer’s instructions and drawing no. MPD-60100. The thing is, the extended dorsal fin per dwg. no. MPD-4004 is a mandatory feature of the model G-21C type design as specified under Master Drawing List (MDL) no. 7 and should have been in place ever since its original re-certification as a model G-21C in 1968, but STC SA4-681 is not applicable to or approved for use on a McKinnon G-21C. STC SA4-681 is actually or at least supposed to be used to install this particular design feature of a McKinnon model G-21C, G-21D, or G-21G on a Grumman model G-21A aircraft still certified under ATC-654.

Soon thereafter, in conjunction with those other recent modifications, Jack Mark and his maintenance staff applied for a “Field Approval” through the Milwaukee Flight Standards District Office (FSDO) and the Chicago Aircraft Certification Office (ACO) of the FAA to “upgrade” the engines on N642 from the original 550 shp PT6A-20 series to the 680 shp PT6A-27 series. On the incorrect and mistaken basis of the McKinnon note under Section III of TC 4A24 that the so-called model “G-21C ‘Hybrid’ turboprop” conversion per STC SA1320WE was supposedly identical to a model G-21E and the fact that the -27 engines were approved as an “option” for the model G-21E, the FAA ACO in Chicago granted the Field Approval.

The irony here is that while the aircraft was never a valid or conforming model “G-21C” in the first place, it essentially was a model G-21E all along and although the means by which the modifications were carried out and approved were not valid, the end result was actually kinda OK.

Image

Even so, there were other problems - elsewhere in this forum, under the “Goose Owners do the Wackiest Things” thread, there is a discussion of another modification done to N642 during the time that it was owned by Jack Mark – one involving an undocumented and unapproved major modification to the main structural bulkhead in between the cockpit and the main cabin and the companionway through it.

There is also a separate thread dedicated to following the comprehensive restoration efforts of the current private owner of N642, who bought it in 2010 from the estate of the late Jack Mark, who died in June 2007.

That same current owner also seems to be a member of the "my money can buy anything" club; based on statements he has made and that are published on its Facebook page (noted elsewehere on this forum as well) he seems to be trying to convert or "upgrade" N642 into a 12,500 lb. model "G-21G" (after all, it's essentially a "free" extra 2,000 lbs. of payload) in spite of the facts that he is not an approved "manufacturer" under FAR Part 21 and has no kind of production approval or authority, there are no STC(s) approved to carry out such an "upgrade" (maybe he plans to get one, but I haven't seen any evidence of that yet - and even if he did/does, that won't make N642 into an actual model G-21G so much as it will be still just a modified G-21C because when used properly, STCs do not change the fundamental or underlying basis on which the aircraft was originally certified. A so-called "McKinnon G-21C" certified under TC 4A24 Section I as N642 supposedly currently is when modified by an STC actually remains certified as a McKinnon G-21C under Section I of TC 4A24.) Also, all of the legacy McKinnon engineering data approved for the conversion or manufacture of a model G-21G is proprietary - and AFAIK the current owner of N642 does not have permission from the current owner of TC 4A24 and the rest of the legacy "McKinnon" engineering data pertaining to the G-21 series, i.e. Atlantic Coast Seaplanes LLC, to use it as required by 14 CFR §21.6 - and he does not qualify for the exemption under 14 CFR §21.6(b) which allows him to do so without permission from the current TC Holder if he can prove he started on it before August 5, 2004. (He didn't even buy the airplane until April 2010.) I have no doubt that he does have access to copies of that engineering data, but not through any legitimate or approved means - which mean that there could be a lawsuit pending down the road....

Those are the only two choices to "build" a model G-21G aircraft - "manufacture" it new under Part 21 with permission from the current TC Holder or "alter" a lesser model G-21 series aircraft under Part 43 with an STC which does not exist - and the only data currently in existence is that same proprietary "McKinnon" data which is owned by Atlantic Coast Seaplanes LLC. Also, even though a modified or altered "lesser" model G-21 aircraft may be made to resemble or even conform as a model G-21G, that still does not make it an actual model "G-21G" aircraft. Many people do not seem to understand that it was actally by means of the former ("manufacture" under FAR Part 21) that McKinnon qualfied his G-21 series conversions under TC 4A24; even though they were in essence just modified/converted from legacy Grumman G-21A aircraft, because he was a certified and approved "manufacturer" under 14 CFR Part 21 and actually owned the TC (4A24) plus the fact that he so extensively rebuilt and replaced critical structure and components of the legacy airframes, his conversions qualified for the most part as "new" built aircraft with 0 hrs. TIS.

In any case, it is evident that the current owner of N642 s also a member of the "I don't have a clue that I can't build a "McKinnon" anything because I'm not Angus McKinnon or McKinnon Enterprises Inc. either" club. If he ever does manage to get N642 re-registered as an actual, i.e. "conforming" model G-21G (as opposed to being still just a "McKinnon G-21C" as it is currently certified, albeit a much modified or "altered" one) it won't, at least not legitimately, be identified as a "McKinnon" G-21G - because McKinnon did not build and certify it as such. As an "amateur-built" copy of a model G-21G aircraft converted from what was actually an illegitmate McKinnon model G-21C in the first place, it might be re-identified as an Atlantic Coast-Vectored Solutions model G-21G (i.e. the current TC Holder hyphenated with the actual "builder") but once again because it will have been only "amateur-built" as such, it would eligible only for an Experimental certificate of airworthiness. His best bet to retain its Standard category certification of airworthiness is to stop trying to make it into an actual model "G-21G" and just focus on making it into a properly "conforming" 12,499 lb. model G-21C for a change. IMHO.
Last edited by Rajay on Thu Aug 08, 2013 5:04 pm, edited 1 time in total.
Rajay
 
Posts: 391
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From the beginning, starting with c/n 1201 - McKinnon style!

Postby Rajay » Tue Aug 06, 2013 10:33 pm

McKinnon serial no. 1205

N5558 / ZK-ERX / N77AQ


Grumman JRF-5 OEM serial no. B-62 was built in May 1944 for the US Navy as Bureau of Aeronautics serial or “Bu.” no. 37809. After the war, it went to Flugfelag Airlines in Iceland in September 1947 and was registered there as TF-ISR. In July 1967 it came back to the US along with a PBY-5A as part of the same deal. Flugfelag sold it to Harold Hansen of Seattle, WA, apparently doing business as American Aviation, Inc. and it was re-registered as N5558, Grumman G-21A serial no. “B-1062”.

Note: that serial number (B-1062) was not valid and seems to have confused the records of 1944 Grumman JRF-5 serial no. B-62 with the earlier 1939 Grumman G-21A serial no. 1062, which was owned by Gulf Oil Co. and registered as NC3042. Eventually it was straightened out, but because of that confusion, when you order copies of the records for N5558 from the FAA archives in Oklahoma City, OK, you also get some that also pertain to N3042, Grumman G-21A serial no. 1062, which was actually a completely different aircraft.

On October 23, 1967, American Aviation Inc. sold N5558, still incorrectly identified as Grumman G-21A serial no. “B1062”, to McKinnon Enterprises Inc. of Sandy, OR. Three days later, McKinnon turned around and sold it to Mr. Charles E. Walters of Spokane, WA, for the sum of $38,015.00. Mr. Walters was the same person from whom just two months earlier McKinnon had bought N501M, Grumman G-21A (JRF-5) serial no. B-138, which he later converted into McKinnon G-21CHybrid” Turbo Goose serial no. 1203 and which was later re-registered as CF-BCI in Canada.

Eleven months later, McKinnon bought N5558 back from Charles Walters on September 20, 1968 with a chattel mortgage note in the amount of $200,000.00. It seems probable that the much higher value reflects additional cash that was part of the deal to be used to finance the anticipated turbine conversion of the aircraft.

After initially documenting its conversion as a turbine model G-21E on an FAA Form 337Major Repair and Alteration” dated May 14, 1969, McKinnon eventually completed and re-registered N5558 as McKinnon model G-21G serial no. 1205 on June 13, 1969 and also made an application for a new certificate of airworthiness for it in the Experimental (Research and Development) category under Type Certificate no. 4A24 on that same day. A month later on July 17, 1969 and after some 23.5 hours for flight testing, McKinnon amended its Experimental airworthiness certification to include showing compliance with FAR Part 23 as well as market survey and crew training.

According to that FAA Form 337 from May 14, 1969, the two Pratt & Whitney 680 shp PT6A-27 turbine engines that were installed on N5558 were consecutive serial nos. PC-E-40043 and PC-E-40044.

On July 17, 1969, , FAA Type Certificate no. 4A24 was amended to include Section III for the approval and certification of the 10,500 lb. turbine powered model G-21E and on August 29, 1969 to include Section IV for the approval and certification of the 12,500 lb. turbine powered model G-21G. As noted previously, contrary to McKinnon’s claim under Section III that a 12,499 lb. four (piston) engine model G-21C that is modified with a pair of 550 shp PT6A-20 turbine engines per STC SA1320WE is “identical” to a model G-21E, the model G-21E was actually essentially identical to McKinnon’s earlier Grumman G-21AHybrid” turbine conversions per STC SA1589WE and to his so-called model G-21CHybrid” turbine conversions supposedly per STC SA1320WE – once again, all of which were re-certified up to only 10,500 lbs. just like the model G-21E.

By contrast, the “real” model G-21C and G-21D aircraft (with four 340 hp Lycoming GSO-480-B2D6 geared, supercharged, “flat” piston engines) were re-certified up to 12,499 lbs. Even after its conversion per STC SA1320WE to have only two 550 shp PT6A-20 turbine engines, the one and only model G-21D (N150M) was limited to 12,200 lbs. – still significantly more than the 10,500 lbs. of those other conversions. Apparently, what mattered most in regard to the maximum gross weight limit of each of these types was not their total horsepower but rather the internal structural reinforcements that they had but which the Grumman G-21A and McKinnon G-21CHybrid” turboprop conversions and the McKinnon model G-21E did not.

In any case, it seems clear that a 12,499 lb. model G-21C modified to have its four 340 hp Lycoming piston engines removed and replaced with a pair of PT6A series turbine engines per STC SA1320WE, especially if they are “upgraded” to the 680 shp PT6A-27 or -28 series, would in fact be more essentially “identical” to the 12,500 lb. model G-21G than it would be to the 10,500 lb. model G-21E.

Finally on September 5, 1969, after a total of about 100 hours of flight testing, McKinnon applied for a full Standard certificate of airworthiness for N5558 as a McKinnon model G-21G under Section IV of TC 4A24. That application was supported by a requisite FAA Form 317Statement of Conformity” certifying its production as an essentially “new” model G-21G aircraft with only those same 100 hours of flight test as its official Time in Service. Because of the extent to which it was “rebuilt” during its conversion, all of the previous time in service it had accumulated in service with the US Navy and with Flugfelag Airlines in Iceland over the previous 25 years was wiped away.
Last edited by Rajay on Thu Aug 08, 2013 5:04 pm, edited 1 time in total.
Rajay
 
Posts: 391
Joined: Fri Jul 23, 2010 6:07 pm
Location: The Southern Part of Heaven

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