That is a very interesting 337 which was field approved for Bruce Kown’s airplane …based upon Duane Shockey’s airplane alteration Form 337. The reason it is so interesting to me is…. it was Duane Shockey who told me only one airplane had that mod approved….and that no other would be.
(and when I passed that info along to the FAA partners they confirmed that (as it applied to their airplane.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
Any progress on that 337? Been watching the list and have not seen it posted yet. About to contact a DER to get the ball rolling and having something showing it had been approved before would go a long way.
At the start of this thread in 2014, the OP stated he received a field approval from Seattle FSDO to remove the fuel pump presumably based upon the approved fuel line configuration in later A and B models. Interestingly, he then reported some difficulties routing these lines on his earlier model airplane. I would have expected that the data supporting his 337 would have described all changes necessary to accomplish the modification. They may have accepted the proposal without fully considering the minor routing changes necessary or whatever other problems arose during actual installation. This may be an example of how different FAA FSDO inspectors evaluate these types of proposals. They are supposed to be “One FAA”, but it doesn’t always work out that way.
I don’t see any reason why this change cannot be accomplished based on the later model Cessna 170 fuel line routing (approved). It’s essentially the same airplane and engine. The approved data to support the modification would consist of drawings and part numbers applicable to the later airplane to be applied to the older model. This submission should be pretty comprehensive so a technician can perform the work in accordance with the approval. A DER would be able to do this in a manner acceptable to the FAA. I believe work by DERs is proprietary which is why it may be limited to one airframe. Questions on whether or not such work can be copied and used by others is a legal matter.
Remember, an FAA approved 337 is not approved data. Hopefully it contains references to, or approved data, but the document itself is just another government form.
CraigQ wrote:Any progress on that 337? Been watching the list and have not seen it posted yet. About to contact a DER to get the ball rolling and having something showing it had been approved before would go a long way.
I sent you a PM.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
voorheesh wrote: … Remember, an FAA approved 337 is not approved data. Hopefully it contains references to, or approved data, but the document itself is just another government form.
Unless that 337 was written prior to October 1, 1955 according to page 14 of FAA Order 8100.16. Harlow, what would it take to get copies of all 337 forms filed with the FAA in OKC prior to Oct. 1, 1955 on 1948-1955 C-170’s? A FOIA request?
Last edited by n2582d on Fri Oct 13, 2023 4:41 pm, edited 1 time in total.
Not sure where those old records were located or what the retention time was. No computers but they did manage registration from a national office so the FAA registration branch might be a good place to start. I know all 337s are filed there now. If those records are public, FOIA is the way to request them. My guess is that pre 1955 records stayed in the office that issued them and probably were eventually purged or possibly sent to OKC at some point for storage. I wonder if any current owners might find pre 1955 repair and alteration documents in their aircraft maintenance records. Like you mention, some might be useful. Good luck!
I found a 337 form dated Dec. 14, 1949 which shows that a 1948 C-170 received approval to replace the original fuel lines and pump with a gravity feed system as on the later models. I've posted it here. This is considered approved data.
One thing to notice is the difference between the 170A and 170B as to where the line from the tank to the rear doorpost enters the cabin/overhead to get to the rear doorpost. Although the IPCs for the two models appear the same in Fig 43 and 63 respectfully…. the actual PNs for those lines are different because the lines take different routes not adequately illustrated in those figs. The B-model enters the cabin overhead in a different location than the A-model. This means the actual routing when converting a ragwing is easier if the A-model routing is followed rather than a B-model. This can be seen if the lower wing root fairing is removed from an A-model.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
Hello again, back with a couple of questions on the re routing as we now have the wings on and I can get back to this matter.
#1 is, for those who did the reroute, did you leave the selector valve in the stock location forward of the trim wheel, or move it aft of the flap lever?
#2 is. Could anyone post or send a picture of the A model area of the fuel line where it exits the fuselage? This has been discussed and we are looking at the area aft of the doorpost below the aileron cables.
I appreciate all the input and will get a few pictures up as soonas I get a place to host them on the interwebb.
Here are a few pics posted in the MX Library that I rec’d from a Member who did this to his ragwing: viewtopic.php?p=152928#p152928
(This particular 170 has it’s fuel-selector-valve in it’s original position on the Flap Tunnell…not the firewall….just to answer that question…. I do not believe a 170 with the valve on the firewall that remained on the firewall would meet a claim that it copied the A-model routing.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
Thank you for the link to those photos. They confirm the location we had been discussing that made the most sense. I had removed the old lines last week and received the new tubing yesterday. Starting the reinstall/mod today.
Thank you (and all) for the help, will try to keep progress posted.
Craig
Poncho73 wrote: ↑Thu Nov 02, 2017 1:29 pm
I thought I would pursue this with Transport Canada, TC have approved me to do so and therefore eliminating the requirement to install the original pump, manifold, two fuels, and a fuel pressure gauge. That's the story....I will need to submit the appropriate paperwork but the main thing is they are good with it.
Keep us posted. Any pictures would be very much appreciated, especially the routing . Who did you contact at TC? I am interested in doing the same thing.
Thanks very much.
I've just read your post regarding re-routing 1948 Cessna 170 fuel line to Cessna 170A style ! Can you bring me up to date on that project!
I have a 1948 Cessna 170 that i've owned since 1995 with no fuel pump , and just recently found out from my new AME that a fuel pump is required !
Having at least 5 AME's over the years and this was not brought up !
So looks like I need to install a fuel pump or my preferred option would be to re-route the fuel lines.
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