Page 1 of 1

N642 restoration project - Everett, WA

PostPosted: Mon Feb 04, 2013 4:14 am
by Rajay
I don't "do" Facebook, but they have most of it opened up to public access:

Re: N642 restoration project - Everett, WA

PostPosted: Sat Jul 06, 2013 5:10 pm
by Rajay
FYI: N642 is a turbine Goose. It was originally built by Grumman as a US Navy model JRF-5, Grumman OEM serial or "construction" number B-137 and it was assigned US Navy Bureau of Aeronautics serial or "Bu." no. 87743. After the war, it was one of four* ex-USN Gooses initially transferred to the Bureau of Land Management, an agency of the US Dept. of the Interior, sometime prior to early 1954 and it was subsequently operated by BLM in Alaska.

(*The four Gooses were ex-USN models JRF-5 Grumman serial nos. B-123, B-137, B-145, and B-130 which had been USN Bu. nos. 87729, 87743, 87751, and 87736 respectively, and which were subsequently registered as N640, N642, N643, and N644. Later, ex-USN JRF-5 OEM serial no. B-115 aka Bu. no. 87721, became N641 with BLM.)

In 1966-1967, McKinnon converted BLM Goose (N640, s/n B-123) to a turbine-engine configuration per STC SA1589WE and afterward, BLM decided to have N642 converted as well. It was done in 1968 - and the modifications done to it were essentially identical to the ones done on N640, but unlike N640 which officially remained certified as a "Grumman G-21A" under TC no. 654, McKinnon claimed to have converted N642 as a model G-21C certified under his TC no. 4A24 (as McKinnon serial no. 1204) in addition to the turbine conversion supposedly per STC SA1320WE.

The thing is - a "real" (i.e. fully "conforming") McKinnon model G-21C is internally structurally reinforced so that it can operate up to 12,499 lbs. but the two so-called model G-21C "Hybrid" turboprop conversions that McKinnon "built" in 1968* were not internally structurally reinforced in the same ways and they were re-certified as a result up to only 10,500 lbs. maximum gross take-off weight - just like the previous "Grumman G-21A" Hybrid turboprop conversions (N640, G-21A serial no. B-123, and G-ASXG, G-21A serial no. 1083) AND just like the later McKinnon model G-21E that was not approved or certified by the FAA until a year later in July 1969. For that reason, those two so-called model G-21C "Hybrid" turboprop conversions (*C-FBCI, serial no. 1203, and N642, serial no. 1204) were not really ever valid model "G-21C" aircraft at all.

Unlike all of his other conversions supposedly done under TC no. 4A24, they apparently were NOT so thoroughly and completely "rebuilt" with new parts that they were "zero-timed" as new aircraft (with 0 hours Time in Service) as were all the rest of the aircraft re-certified uder TC 4A24. McKinnon also apparently never submitted the requisite FAA Forms 317 "Statement of Conformity" certifying their "production" as new McKinnon aircraft - or of course their "conformity" as supposed models "G-21C" - because they actually did not so conform regardless of their supposed simultaneous turbine engine conversions per STC SA1320WE. (Yes, they was a whole lot of "supposing" going on.... Maybe too much.)

Now, in addition to "restoring" N642 (a job at which his staff is doing an excellent job from what I can see on the above referenced Facebook pages) - a term which would apply only so far as taking it back to its "original" 10,500 lb. Grumman G-21A "Hybrid" or McKinnon model G-21E configuration (because that's what it really was after McKinnon's initial conversion in 1968) the current owner seems to think that he can also "upgrade" it to become a 12,500 lb. "McKinnon G-21G" just like the current owner of N640 claims to have done on it between 2001 and 2005.

They are both wrong in my professional opinion as an expert on this subject matter. There has never been any means approved by the FAA by which a private owner can upgrade or convert (officially speaking "alter") a lesser version of a G-21 series Goose to a model G-21G configuration "in the field" as a "major alteration" under 14 CFR Part 43. There is no STC (or even multiple STCs) by which such a "major alteration" can be accomplished. The only engineering data that has ever been approved to do that job is the raw manufacturing data incorporated within TC no. 4A24, which is currently owned by Atlantic Coast Seaplanes LLC (d/b/a Antilles Seaplanes LLC) in North Carolina. In order to use that data, someone must have both written permission from the TC Holder - i.e. a license agreement Ref. 14 CFR ยง21.6(a)(1) - and be FAA certified or approved in their own right as a aircraft "manufacturer" under 14 CFR Part 21. In other words, they must obtain a Production Certificate (PC) or an Approved Production Inspection System (APIS) or some other kind of primary manufacturing "quality" system approval from the FAA. Even so much as a secondary manufacturing approval - such as a PMA - would not be enough, and these two private owners did and do not have even that much.

Note too that even if they had had STCs approved for this kind of use, the aircraft so modified would still not be officially re-identified as a model "G-21G" much less a "McKinnon G-21G" because McKinnon did not actually "build" or ever officially re-certify them as such. In terms of modifications made with STCs "in the field" under 14 CFR Part 43 by private owners, a "modified" (in these cases) "Grumman G-21A" is still just a "Grumman G-21A" in terms of its official identification on, for examples, its FAA Certificates of Registration and Airworthiness.

In order to be offically re-identified as anything else, such as an actual model "G-21G" for example, the private owner / builders would have needed at least the aformentioned permission / license agreement from the TC Holder - in which case the converted aircraft would be properly re-identified in terms of the current (at that time) TC Holder's name hyphenated with the name of the owner / builder who did the actual conversion so that it would be distinguished from any "factory-built" examples of the type still in existence. Such an aircraft would also have to be identified by a unique serial number that must also be of even a different format than an original "factory" serial number to prevent it from being confused with an actual "factory" issued serial number. Also note that without any kind of manufacturing approval under 14 CFR Part 21, the converted aircraft would be considered to be "amateur-built" and as such, it would be eligible for only an "Experimental" certificate of airworthiness.

In the case of N640, which the current owner of N642 seems to be trying to emulate, it was converted by the owner of Teufel Nurseries Inc. at a time when TC 4A24 was owned by Aero Planes LLC and as far as I can tell, Teufel never had any kind of manufacturing approval under 14 CFR Part 21. Therefore, instead of now being a "1944 Grumman / McKinnon G-21G serial no. 1201" as it is currently registered, N640 should be offically identified either still as "1945 Grumman G-21A 'Hybrid' Turboprop serial no. B-123" - just as it was still identified after McKinnon's "original" conversion in 1967 - or a valid case could be made that it could now be validly identified as a "2005 Aero Planes / Teufel G-21G" with an Experimental CoA - but it would have to have a completely new and different serial number than "1201" because not only is that serial number the same format as an actual "McKinnon" serial number, that exact same serial number was in fact already previously issued to and used by a completely different aircraft (N150M) and then supposedly "retired" when N150M ("1958 McKinnon G-21C serial no. 1201") was subsequently further converted and re-certified in June 1960 as McKinnon G-21D serial no. 1251.

Regardless, IMPO the example of N640 is a particularly bad one for the current owner of N642 to be trying to follow...