1948 170 Rebuild

[Stick.Back.Aviation]

From the legality standpoint… it would be better to transplant the 170A-model gearbox to the 170… rather than switch the 170 dataplate to the 170A fuselage.

There was a couple hours yesterday where I was considering the latter. I think with the above information about interchangeability my only recourse is to proceed with the former. It's easy to want to give in to the "no one will know and of the ones who do, none of them will care" but I want this thing to be bonafide.. can't justify any shortcuts

[cessnut]

If all the parts from the 170A fuselage section were the same as the 170, I don't see any legal ramifications to installing serviceable parts and reattaching the data plate. Since we know they are not, you are left with using what parts you can to repair your fuselage. "Transplanting a gearbox" is not a thing that just happens. The aircraft was built around it. As far as hole alignment goes, certain things will line up, others TBD. The gear casting bolt holes and Hi-Shear holes should line up. The biggest issue will be whether the bulkheads line up with the doorpost. I can see the exfoliation on the outboard gear castings. Are your bullheads corroded beyond use?

[Stick.Back.Aviation]

If all the parts from the 170A fuselage section were the same as the 170, I don't see any legal ramifications to installing serviceable parts and reattaching the data plate. Since we know they are not, you are left with using what parts you can to repair your fuselage. "Transplanting a gearbox" is not a thing that just happens. The aircraft was built around it. As far as hole alignment goes, certain things will line up, others TBD. The gear casting bolt holes and Hi-Shear holes should line up. The biggest issue will be whether the bulkheads line up with the doorpost. I can see the exfoliation on the outboard gear castings. Are your bullheads corroded beyond use?

Pretty much everything is corroded but surprisingly little is corroded beyond use. I am going to be replacing a lot but I think I can clean up and patch a fair amount as well.

[GAHorn]

If all the parts from the 170A fuselage section were the same as the 170, I don't see any legal ramifications to installing serviceable parts and reattaching the data plate. Since we know they are not, you are left with using what parts you can to repair your fuselage. "Transplanting a gearbox" is not a thing that just happens. The aircraft was built around it. As far as hole alignment goes, certain things will line up, others TBD. The gear casting bolt holes and Hi-Shear holes should line up. The biggest issue will be whether the bulkheads line up with the doorpost. I can see the exfoliation on the outboard gear castings. Are your bullheads corroded beyond use?

It is ILLEGAL to move a dataplate from one fuselage to another. Period.

45.13(e) No person may install an identification plate removed in accordance with paragraph (d)(2) of this section on any aircraft, aircraft engine, propeller, propeller blade, or propeller hub other than the one from which it was removed.

[cessnut]

George, I didn't discern from this thread that anyone intended to falsify records by switching fuselages. The discussion has been about changing parts on his fuselage. There is nothing illegal about changing as many parts as needed to repair his fuselage. That is not the spirit or intent of 45.13. The regulation says aircraft, not fuselage.

[GAHorn]

I used the word “fuselage” in the context of this thread, as (I sensed) it discussed the possibility of moving the plate to a different fuselage, which would violate the intent of the rule.
I’m not trying to dictate what others might do, I was only trying to point out what is in-accordance with the rule.

[n2582d]

Order 8100.19 Chapter 4,(3)(b):

For an aircraft to be considered eligible for repair, it must have at least one primary structure around which a repair can be performed; otherwise, the action would constitute a replacement of the aircraft. The FAA considers an aircraft’s primary structure to be the structure that carries flight, ground, or pressurization loads, and whose failure would reduce the structural integrity of the aircraft.
c. The FAA does not consider an aircraft to be repairable if all primary structures of the aircraft must be replaced. Replacement of some major components of an aircraft would be considered a repair, but replacement of all of the primary structures of the aircraft is not a repair but a replacement of an aircraft. If the identification plate from the original aircraft were placed on the aircraft this action would be prohibited by 14 CFR § 45.13(e) which states that “No person may install an identification plate removed in accordance with paragraph (d)(2) of this section on any aircraft, aircraft engine, propeller, propeller blade, or propeller hub other than the one from which it was removed.”

My interpretation of this allows for replacing the fuselage if the original wings (or even one wing) is original.

Tyler,
The 170 — or any Cessna — definitely does not have matched-hole skins like an RV does. I think you’ll want to use your existing skins as patterns rather than to try and use skins from your donor aircraft. My plane had two additional access holes in the top gearbox skin (p/n 0513006-11) — an illegal, undocumented alteration. Unless you’re a sheet metal guru, you’ll want some sort of access to buck the rivets inboard of the inboard landing gear supports (p/n 0511495-34,-35). AK180-2 provides acceptable data to install an access hole in the bottom skin.

[cessnut]

To be sure, I wasn't trying to start an argument. I think we all have the same goal of helping a guy out with some insight. FAR 1 provides a good definition of an airframe.

The numbness in my fingers will attest that you can buck all the rivets without adding holes. If you are not a sheetmetal guru, find one to guide you before you start drilling. It's not easy to get that all back together correctly.

[Stick.Back.Aviation]

I appreciate all the information. I was always under the impression "the data plate was the aircraft. My current plan of action is to maintain the aft A pillar where the data plate is riveted, so luckily I will not have to cross in to any such territory. I am no sheet metal guru, but I have done a small/fair amount of sheet metal work. I started drilling already! Between my 9-5 I use to pay my bills and the side project I do to pay for project parts I didn't get a single chance to work on the 170 yesterday. I am hoping today I will have a couple minutes even if its just on my lunch break.

I will definitely keep you guys updated of any exciting progress. I removed a line of rivets and started to pull up the floor. The first thing I am trying to remove is the section in front of the bulkhead assembly (like where the intrument panel is mounted).

I'm almost certain this project is too far gone to be a practicable restoration. Good thing I'm so damn stubborn. It will fly again.

Tyler

[GAHorn]

I appreciate all the information. I was always under the impression "the data plate was the aircraft…

Tyler

That belief/opinion was persistent and common for many years and it remains an opinion in the minds of some die-hards. I once thought it “OK” also because that’s what so many “old timers” would repeat. FAA has clarified and become stricter about this in recent years.

[Poncho73]

The 170 and the 170A will be the same with the exceptions of course those new things added to the A the 170 didn't have. One this comes to mind is the fuel lines and the fuel selector would be different between the 170 and the 170A. The 170A being preferred. However you'll have to look at the fuel line routing to see if you can make that work to the aft location of the 170A routing. And of course there would be legalities to deal with.

Yes I converted my 48 fuel system to the 49 and sub routing. Big job, but that carcass shows the fuel line routing fairly clearly, especially easy when the floor is not installed!

[cessnut]

Looking forward to some more pictures of the progress. If you have the original cabin top skin you might want to fasten that in place before you take too much apart. To remove the aft bulkhead you will have to remove the door sills, at which point you will want to cross brace across the door openings.

If you had to replace the doorpost where the datatag is located, it would be legal to reinstall the datatag on the new post. You would not have changed the aircraft, the airframe, or even the fuselage for that matter. George is right. The days of drilling data plates off of wrecks and moving them to another aircraft are behind us. I don't doubt that is the history of some of these old planes that we love. However, changing major components and reattaching the data plate to the same aircraft is not illegal.

[cessna170bdriver]

Fortunately the parts of mine that all the other parts attach to were still intact.

[Stick.Back.Aviation]

Fortunately the parts of mine that all the other parts attach to were still intact.

654C1773-5DB0-4C5F-9A14-7E0F831BBC17.jpeg

7B943C33-6D40-481D-AB14-B380CFCA897B.jpeg

Now that is a JIG

[voorheesh]

Looking forward to some more pictures of the progress. If you have the original cabin top skin you might want to fasten that in place before you take too much apart. To remove the aft bulkhead you will have to remove the door sills, at which point you will want to cross brace across the door openings.

If you had to replace the doorpost where the datatag is located, it would be legal to reinstall the datatag on the new post. You would not have changed the aircraft, the airframe, or even the fuselage for that matter. George is right. The days of drilling data plates off of wrecks and moving them to another aircraft are behind us. I don't doubt that is the history of some of these old planes that we love. However, changing major components and reattaching the data plate to the same aircraft is not illegal.

As someone who has some insight on legalities, I would suggest that questions about the data plate are the least of your worries. Reading this thread, it appears you have two distinct airframes (or portions thereof) in marginal conditions/states indicating you may want to use portions of each to combine into an airworthy (safe) aircraft. And while it sounds as if you have some qualifications, this may be your first attempt at major airframe work. I suggest you look at those jigs in the pictures from Miles, because that is very likely the scope of repair and assembly you are facing. And consider that the expertise and equipment to accomplish such a job is not found in every repair shop or with every technician hanging around our local airports. At the very least, an inexperienced mechanic or owner would need serious direction and supervision for something like this. There is absolutely nothing wrong with you taking on such a project provided you recognize the need for this direction and defer to someone who is qualified.

I suggest you find a person who can assess your project in person before making any major decisions or performing any repairs or assembly. (As Ghostflyer also mentioned.) I have seen examples of well meaning owners who dive into projects like this and end up with serious even dangerous problems. These include at least one airplane that, on the surface looked perfect, but had hidden serious defects of which the owner was totally unaware.

Sorry to lecture, but it is intended to help you. By the way, thank you for your interest and energy to getting a great old airplane back in the air. Best of luck and look forward to hearing more on your progress.