1948 170 Rebuild

How to keep the Cessna 170 flying and airworthy.

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Stick.Back.Aviation
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Re: 1948 170 Rebuild

Post by Stick.Back.Aviation »

voorheesh wrote:
cessnut wrote: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.
I do not feel lectured and appreciate you taking the time to voice some valid concerns. I was blissfully planning on doing all of this at my house. My second job out of A&P school was at Kenmore Air in Seattle WA, and I was always impressed by the jigs they used to rebuild wrecked beavers. I thought they only did that because those planes had been wrecked. I figured two straight fuselages would go back together straight. I understand how ignorant it sounds but up until you guys started posting pictures of jigs and talking about jigs I was operating under the pretext that I have cleco clamps and the holes will line up. I have a vast pool of experience to draw on in the aviation community, but no one here in Florida with a jig. Some of my most valuable aviation mentors have encouraged this activity whole sale. It seems like my best course of action is to hot swap the gear box, but as another member stated "the plane is built around it". Looking in there it looks like I could get to it and change it. That would eliminate a lot of the trouble of needing a jig. Might be a fool's errand. This plane seems like a "there has to be a horse in here somewhere" sometimes. I could get more for the prop than I paid for the whole project... but she deserves better.

Still motivated. Will keep yall updated.
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cessna170bdriver
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Re: 1948 170 Rebuild

Post by cessna170bdriver »

Stick.Back.Aviation wrote:

Now that is a JIG
A Cessna-built jig, now owned by Mountain Airframe in Mena, Arkansas. You might want to look them up and talk to Del Lehmann and/or Brett Ham. They have a lot experience with this level of repair to Cessna 170’s.
Miles

“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
Stick.Back.Aviation
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Re: 1948 170 Rebuild

Post by Stick.Back.Aviation »

cessna170bdriver wrote:
Stick.Back.Aviation wrote:

Now that is a JIG
A Cessna-built jig, now owned by Mountain Airframe in Mena, Arkansas. You might want to look them up and talk to Del Lehmann and/or Brett Ham. They have a lot experience with this level of repair to Cessna 170’s.
I just got off the phone with Del. He said if both airframes are true it can be done using triangulation and bracing. That is the reassurance I needed :)
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GAHorn
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Re: 1948 170 Rebuild

Post by GAHorn »

If you have a straight airframe a jig can be made to “fix” it from movement as you drill-off parts. That jig can then be used to either hold the disassembled airframe stationary until the replacement part is installed…. or can be used to align a different airframe to install parts.
I have plenty of pics of airframes so-treated undergoing extensive repair. (unfortunately those pics are not in digital format and not easily scanned)
'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. ;)
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cessnut
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Re: 1948 170 Rebuild

Post by cessnut »

That's kind of what I was trying to say without making you overconfident. A lot can be accomplished with locally fabricated fixtures and bracing. The end result will be the sum of the patience and skill of the person doing the work. I once replaced the gearbox and everything between the doorposts on a 185, with the exception of the roof skin, by removing the engine and wings, building custom supports that matched the profile of the belly, and riveting cross braces across the door openings. I also spent a fair bit of time on the phone with a guy who had done many such repairs. There is a way to remove and reinstall the gearbox components and keep everything aligned. Remember that your lift struts tie into that structure and the hole location is critical. I echo what I said before. Find someone who has done it before, take their advice, and come up with a well thought out plan. You sound like a smart guy, and I don't think you will let exuberance get in the way of good decision making.
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ghostflyer
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Re: 1948 170 Rebuild

Post by ghostflyer »

It was only doing the SIDS inspection that I realised my wedges [shims] were fitted upside down on one leg. [LH]. My aircraft was originally a project aircraft that i built /finished up. There was nothing in the logs about a gear box replacement at all. I had a number of qualified people measured and remeasured the aircraft using a laser and other devices to check alignment ,spacing of rivets etc. To me it was too perfect . The 2 guys that started the rebuild [gearbox] were then deceased when i took on the task of the project so i couldn’t ask. However I asked one of the surviving wives [to see if she had some old paperwork] and she told me “Brian “ got a donor box from the USA and it came out of a Cessna 206. YEA, sure was my thought. Then somebody who has an aircraft rebuilding business on the airport stated that “Brian “ used a Cessna 206 box. I do not smoke the funny weed but the sources of that rumour is hard not to believe as it came from very different sources. BUT it works well.
PS. The 2 guys that did some of the restoration of the aircraft were part of a gliding committee that owned the aircraft. So there were 10 experts [committee ] that was directing traffic. It was a drinking party that was only matched in heaven . When I took over , a hangar clean up had to be done and i had 3 wheel barrows of empty beer cans to the rubbish bin. There was 2 full cans found in the rubbish.
Last edited by ghostflyer on Mon Feb 13, 2023 1:20 am, edited 1 time in total.
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GAHorn
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Re: 1948 170 Rebuild

Post by GAHorn »

ghostflyer wrote:It was only doing the SIDS inspection that I realised my wedges [shims] were fitted upside down on one leg. [LH]. My aircraft was originally a project aircraft that i built /finished up. There was nothing in the logs about a gear box replacement at all. I had a number of qualified people measured and remeasured the aircraft using a laser and other devices to check alignment ,spacing of rivets etc. To me it was too perfect . The 2 guys that started the rebuild [gearbox] were then deceased when i took on the task of the project so i couldn’t ask. However I asked one of the surviving wives [to see if she had some old paperwork] and she told me “Brian “ got a donor box from the USA and it came out of a Cessna 206. YEA, sure was my thought. Then somebody who has an aircraft rebuilding business on the airport stated that “Brian “ used a Cessna 206 box. I do not smoke the funny weed but the sources of that rumour is hard not to believe as it came from very different sources. BUT it works well.
It may be helpful to recall that Cessna made a “SkyWagon” (C-180…a companion to the C-170)…. and a “Super-SkyWagon” (No, not the 185 which was also a “SkyWagon”….but the “Super-SkyWagon” C-206).
'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. ;)
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ghostflyer
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Re: 1948 170 Rebuild

Post by ghostflyer »

We had the SIDS program forced upon us and thus a very detailed inspection had to be carried out . This inspection wasn’t flexible at all. The aircraft was stripped totally and I found my whole aircraft had been zinc chromated at one stage of its life . The gear box section was closely inspected as a rumour around was it had been replaced . It looked too perfect. All parts had been zinc chromated before assy. There wasn’t any elongated rivet holes ,all rivets used were correct in type and size. I had access to both a cessna 170b and a cessna 170 rag wing . Both were in a state of disassembly . 2 of us were using a lazor to check alignment . What started us off the L/h gear leg shim pak was opposite to what the R/H shim pak was. Both the cessna 170 and the 170b that we were using as examples had repairs to their gearboxs in the past.
Stick.Back.Aviation
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Re: 1948 170 Rebuild

Post by Stick.Back.Aviation »

Good morning,
I had been scratching my head about this for a few days. I moved the 170A fuselage back in the garage and there was a cardboard box in the way. My friend that helped me unload had to get back to his wife and we were just dumping stuff that I would organize later. I also have parts from my (so far failed) aeronca chief out there and I wasn't paying no mind to this box. Anyways I just looked in it and there are 2 sets of the inboard landing gear angle brackets and one single outer LG bracket. This comes as a welcome surprise. Felt a little like Christmas morning opening that box!!
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Stick.Back.Aviation
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Re: 1948 170 Rebuild

Post by Stick.Back.Aviation »

Good morning!
I was working on the wing last night because I got home from the airport too late to buy running pneumatic tools outside (so I run them inside). I popped the last fuel tank out and found the fuel tank well skins all need to be replaced. I spent the better half of an hour last night trying to find them, but cannot. The hat channels appear to be tac welded onto the skin. I was thinking I would make an owner fabricated part and just rivet hat channel to aluminum. I cannot find the hat channel stock anywhere. I do have access to a brake at the airport if I need to make my own hat channel. I included a picture of mine and one that was for sale on ebay for a 120/140 (but it looks the same for reference). I'm not going to label them and see if you guys can guess which one is which :wink: .
What is the smart move here?

Thank everyone who is still wading into this long and winding post.
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ghostflyer
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Re: 1948 170 Rebuild

Post by ghostflyer »

The one on ebay does it have the same part number . It might “look” the same BUT ,does it have the same thickness and aluminium type . Many people assume 2024 T3 is used every where But surprising it does not . One would question the condition of the ebay part and it’s aluminium condition under the hat sections also as the top side has been clean rigorously . What does the cessna 100 series structural repair manual say? .This is an area of the wing where I would be seeking “expert” advice if you were going to creat an owner produced part. “PLEASE” do not glue felt to the top of the hat sections . Use only closed cell foam rubber on top of the hat sections .
PS. I hate the use of Ebay parts . To me it’s a place where the owners are trying to off load rubbish .
Stick.Back.Aviation
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Re: 1948 170 Rebuild

Post by Stick.Back.Aviation »

ghostflyer wrote:The one on ebay does it have the same part number . It might “look” the same BUT ,does it have the same thickness and aluminium type . Many people assume 2024 T3 is used every where But surprising it does not . One would question the condition of the ebay part and it’s aluminium condition under the hat sections also as the top side has been clean rigorously . What does the cessna 100 series structural repair manual say? .This is an area of the wing where I would be seeking “expert” advice if you were going to creat an owner produced part. “PLEASE” do not glue felt to the top of the hat sections . Use only closed cell foam rubber on top of the hat sections .
PS. I hate the use of Ebay parts . To me it’s a place where the owners are trying to off load rubbish .
I appreciate the response. It was included for reference only. The listing has ended and I have no intent of using an ebay 120/140 part anywhere on my plane. Especially from a listing that did not have any part number listed at all. The metal is Clad 24ST which the internet told me is the old school name for 2024. I asked some of my aviation mentors and the consensus was bending hat channels to the correct height and riveting them on to a piece of sheet metal would be an acceptable alternative. The existing channels are 1 inch wide which might be too narrow to do on a brake. I have to try it tomorrow. I was told widening the channels to the minimum I could fabricate on a brake would be alright.
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GAHorn
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Re: 1948 170 Rebuild

Post by GAHorn »

While not “original”….There are structural adhesives which can likely be used in lieu of spot-weld or riveting those hat-sections.
Our Member Del Lehman in Mena has experience with these products and might be a good advisor to visit.
'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. ;)
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cessnut
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Re: 1948 170 Rebuild

Post by cessnut »

If you have trouble with the brake, you might check around for a local fab shop with a press brake that could accurately bend those hat sections to the correct dimensions and radius. Riveting is fine. Standalone structural adhesives scare me. I have seen bonding and corrosion issues from improper surface prep. Not worth the hassle for the time it would take to drill, dimple and rivet. Just don't consider welding again. Spot welding 2024 requires equipment not accessible to most of us.
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GAHorn
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Re: 1948 170 Rebuild

Post by GAHorn »

Almost every Boeing or Airbus one might ride in today is put together at least in portions using structural adhesives.

These hat sections are not structural load-bearing surfaces…they are supportive of fuel tanks almost as “spacers” for fitment.
'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. ;)
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