The International Cessna 170 Association

Can I use later 172 door hinges on the 170B?

My upper hinge is bent where the pin goes, I have a 172 hinge that matches the rivet pattern on the door but it is shorter then the 170 hinge.

Wondering if we just need to replace the hinge on the frame or if we would have to replace the bottom one as well?

Hinges are made out of steel and can be backyard fixed in many fashions. When you say bent, you’ve had a unfortunate incident with the door.? Note a small bend is normal (factory) for most 170B upper hinges. Hinges can be bought new from Mcfarlane https://www.mcfarlaneaviation.com/produ ... 0511280-6/.
Yes expensive but the upper aft hinge portion is a pain to replace. likely you only want to do it once.

Yes, a friend was taking off the door, he let go of the door with only the top pin in and where the pin goes bent open and the door fell.

Already have the old hinge off, was hoping to find one I guess it looks like the McFarlane one for $500 is the only option?

It’s hard to visualize your problem without a picture but the steel door hinges are fully repairable no matter what is wrong short of totally destroyed. A good tig welder and probably even a good gas welder can replace the worn/damaged hinge segments. The upper hinge on the door side (the long one) can be repaired on the door but the fuselage side and lower door side hinge should be removed for repair.

7mm steel brake line available at your auto supply is the correct size for the hinge segments and hinge pins. Remove the worn/damaged hinge segments completely but leave enough undisturbed to make sure and maintain the hinge segment orientation. Weld the 7mm brake line onto the hinge plate then carefully remove the material where the matching hinge segments go. Remove a little at a time until the fit is perfect. The “new” hinge will last for years. The short segments can be extended some to provide more support area if you choose.

Be advised the upper hinge half that is attached to the door does have a slight bend in it at about half-way down its length. Looking down the side of the plane, there is a slight angle between the plane of the door and the forward fuselage and the slight bend in the upper hinge takes this into account. Don’t try to straighten it out.

172 hinges are different because they set up a different geometry with the way the door opens. Remember a 172 is not ina 3 point attitude on the ground. If you convert a 172 to a tail dragger or simply push the tail to the ground, then open the door, the door will be heavy and want to close on you. The 170 hinge allows the door to swing open more level and not want to swing closed on you.

alaskan9974 wrote:Can I use later 172 door hinges on the 170B? ...

You kinda have to provide a little more info than that.... What do you mean “later 172”?
Are you referring to the part that attaches to the door? Or the doorpost?
Is it the left or right?

Here’s a pic of a ‘62 172 right door hinge area...with a 170B doorpost hinge sitting above it.... Does that answer your question?

Later 172, like a 56. I found a 170b hinge at the salvage yard. The part where it curls over snapped off.

alaskan9974 wrote:Later 172, like a 56. I found a 170b hinge at the salvage yard. The part where it curls over snapped off.

1956 170 and 172 top hinges are the same but different than any other model year 170.

My iPad is being replaced otherwise I could take a few pictures of how to repair your hinge. But what I did 15 plus years ago was rivet the same profile aileron hinge into where the tabs are broken off. trim off the broken part, drill out the rivets, fit it together so the door alines properly, drill new holes in the aileron hinge and rivet it together. I can't remember if the the hinge I used was piper hinge. it has been working fine and takes no time and no welding involved. tracking says my new iPad is on its way so if you can wait I will post some pictures of the repair. If not call me at 250-638- 183zero. cheers Bill

alaskan9974 wrote:Later 172, like a 56. I found a 170b hinge at the salvage yard. The part where it curls over snapped off.

A ‘56 172 is not a “later” 172. It’s an “early” 172... it’s the first 172 produced. Bruce has given the answer....

The ‘56 170 and ‘56 172 came down the same assembly -line. The story given is that the ‘56 172 were so similar the 172 actually had DUAL gear-boxes so that the main gear could be postioned at the front doorpost (a la 170) or at the rear doorpost for a tricycle gear installation. (I’ve not personally confirmed the story by actual observation, but it is a persistent one.). Anyway, it’s best to obtain a copy of the IPC for the 170B and the 172 and compare the PN’s to determine there’s any likelihood of interchangeability. In this case, the PNs for the upper door hinge assy’s are different, which may not be conclusive but is indicative they are not the same.

The 170B (all the way thru the ‘56 model) upper hinge assy (L) is 0511106-106 And the ‘56 172 (SNs 28000-46754) is 0511280-1... quite different numbers.

Going from memory when I did this research. First from personal observation of an actual 1956 170, both the left and right top hinges are the same but different than earlier 170s. A search of the IPC confirms this. The part numbers are the same for a 172 how ever the IPC has another mistake in it. It only has the later number for either the right or left hinge, I can not recall which.

This all was hashed over here 4-5 years ago when I first realized the top hinges were different while viewing a '56 at the 2013 Bardstown, KY Convention.

McFarlane Aviation now has new PMA door hinges and pins. They fit and work great!!
https://www.mcfarlaneaviation.com/produ ... CDHP-KT-1/


John

GAHorn wrote:

alaskan9974 wrote:Later 172, like a 56. I found a 170b hinge at the salvage yard. The part where it curls over snapped off.

A ‘56 172 is not a “later” 172. It’s an “early” 172... it’s the first 172 produced. Bruce has given the answer....

The ‘56 170 and ‘56 172 came down the same assembly -line. The story given is that the ‘56 172 were so similar the 172 actually had DUAL gear-boxes so that the main gear could be postioned at the front doorpost (a la 170) or at the rear doorpost for a tricycle gear installation. (I’ve not personally confirmed the story by actual observation, but it is a persistent one.). Anyway, it’s best to obtain a copy of the IPC for the 170B and the 172 and compare the PN’s to determine there’s any likelihood of interchangeability. In this case, the PNs for the upper door hinge assy’s are different, which may not be conclusive but is indicative they are not the same.

The 170B (all the way thru the ‘56 model) upper hinge assy (L) is 0511106-106 And the ‘56 172 (SNs 28000-46754) is 0511280-1... quite different numbers.

(I’ve not personally confirmed the story by actual observation, but it is a persistent one.) It's true, I helped a friend convert his '56 172 to a taildragger and both sets of gearboxes were there.

Joe
4518C

A couple of months ago I was on the verge of fabricating new hinge pins from a couple of stainless rods (I still had the temporary pins I made from brazing rods in the hinges, from our interior refresh a few years ago, and was getting worried about the softer brass starting to wear), but instead decided to purchase the McFarlane hinge pin set. A little expensive but they are beautifully constructed and fit precisely. Slightly difference sizes for the upper vs. lower hinges so there is zero slop. I don't regret that purchase in the least - highly recommended if you can accommodate the cost.

brian.olson wrote:A couple of months ago I was on the verge of fabricating new hinge pins from a couple of stainless rods (I still had the temporary pins I made from brazing rods in the hinges, from our interior refresh a few years ago, and was getting worried about the softer brass starting to wear), but instead decided to purchase the McFarlane hinge pin set. A little expensive but they are beautifully constructed and fit precisely. Slightly difference sizes for the upper vs. lower hinges so there is zero slop. I don't regret that purchase in the least - highly recommended if you can accommodate the cost.

About 20 years ago I noticed the doors on the 170 had a bit more “play” in the hinges than I liked... sufficient to make it “iffy” for the “hatch latch” to mate properly. I went to TSC Airmotive and found a selection of hinge pins of various wire gauges.... and found the combination of upper/lower that got rid of that slop.

(TSC is Tractor Supply Co.)