Want to re-fabric metalized 170

[ROCKY]

What needs to be done to go back to fabric on a 48-170. Do the ribs need to be replaced? has anyone on this board done this or know someone that has. I've asked other A&P/IA types and get a wide range of answers, but no one knows of anyone that did it, or how they did it. ANYONE?

[Bruce Fenstermacher]

Rocky I'd say it depends on what was done to metalize them. The worst case you remove all the metalizing mods which means replacing parts that were modified. You might be able to leave modified parts if their modification will have no effect on the airworthiness of the plane. You asked about the ribs. Were they drilled out to rivet metal to them? Will they still hold the clips which is the approved method of attaching the skins? Here in lies the rub. Who's going to decide something is airworthy that has been modified.


Of course you will also have to re-install any parts that were removed. I'm thinking drag wires but the metalized example I've seen still had them.

[FredM]

Consider this, when your wings were metalized, it required an STC and was considered a major alteration. Returning it to fabric will also be a major alteration. It will also require approved data that addresses the issues bruce brought up, what to do with the drilled ribs etc. This seems like an enormous undertaking to me. The only simple way to do it that I can see is simply replace the wings. This would probably be the least expensive option as well.

[Fearless Tower]

Not sure about the least expensive.....but replacing the wings is the only right way to do it because of the drilled out ribs from the metalization.

If you really wanted to convert it back to a rag wing.....your best bet is to call Univair and see about buying the brand new (uncovered) wings:

Wing for 1948 C-170, uncovered,
without flaps and ailerons,
RH ..............................0520002-15 ....$7,184.44
LH ..............................0520002-16 ....$7,184.44

No idea how long it would take to get them (I am sure it is a special order), but you'd be able to go back to a ragwing. But once it is all said and done, it will cost you WAY more than the whole airplane is worth.

You could probably do it cheaper buy finding salvage wings, but that could be problematic finding a parted out 170 with wings in good condition.

All said, in the current market, it would be much cheaper to find another '48 for sale that is in good condition and still has the fabric wings.

[GAHorn]

It may be possible to return the aircraft to fabric, but it will entail some close study. If the fabric can be re-attached by by stitching and by using old/or drilling new holes say, a half-inch from existing holes....
The problem is complicated by the questions around how the metal as attached, and how the new fabric will be attached (Martin clips? PK screws? Stitching?) ...and if all the old/original structure is still present.

It's gonna be a detail-challenging project.

[ROCKY]

It may be possible to return the aircraft to fabric, but it will entail some close study. If the fabric can be re-attached by by stitching and by using old/or drilling new holes say, a half-inch from existing holes....
The problem is complicated by the questions around how the metal as attached, and how the new fabric will be attached (Martin clips? PK screws? Stitching?) ...and if all the old/original structure is still present.

It's gonna be a detail-challenging project.

All the original structure is there, i'm going to re-fab the leading edge metal, and clean up some minor defects, my concern is the fact that the ribs all have the extra holes from being metalized.... I'm going to Stitch and apply seam tape to the ribs, the ribs are in good shape other than the extra holes. Is there anything preventing me from leaving the extra holes in the ribs and putting the fabric back on the wings.

[GAHorn]

Using reinforcing/seam tape on the ribs might be the only economical answer. If you can discern that the ribs are not compromised by the other holes, then I can see no reason it wouldn't work just fine. (I'm not the most experienced fabric guy here, tho'. I'm sure others can make a more useful contribution.)

[ROCKY]

Using reinforcing/seam tape on the ribs might be the only economical answer. If you can discern that the ribs are not compromised by the other holes, then I can see no reason it wouldn't work just fine. (I'm not the most experienced fabric guy here, tho'. I'm sure others can make a more useful contribution.)

Thanks ..... This is the reason I've come here for feed back. you guys have seen it done or know someone who has when it comes to the 170. as far as the ribs go I think they are good to go, but would like others to give some input, and maybe point out something i may be overlooking.

[FredMa]

Since this is a major repair and you are going to have an IA, you are going to have something in writing to show that the drokked out holes are acceptable as is. The trouble is I don't think you are going to find any such reference. I believe your best bet and cheapest would be to advertise your wings for sale and find someone that has a ragwing that wants to go to metalized wings, Trade wings and go from there.

[FredMa]

Sorry, (DRILLED) out holes.

[GAHorn]

Fred, there are many many instances of ribs with excess, unused holes being recovered in fabric and not utilizing excess holes. That situation does not in itself make the entire wing, or even individual ribs, unairworthy or past the point of being recoverable.
Martin or Cessna clips often damage holes that are ignored, taped over, and new holes drilled nearby for PK screws or other clips. And many wings are recovered using good old rib stitches and reinforcing tape and ignoring hundreds of previously existing, no longer used holes.
This is more than likely going to have to be a subjective decision made on the scene by the owner and his inspector. IMO

[Bruce Fenstermacher]

You can not stitch the fabric to the wings like a Cub. This is not the approved method for the Cessna. The clips are the approved method. If you can not use the clips you need to get approval for some other attach method ie stitching.

[GAHorn]

We were simultaneously typing, Bruce.
The instructions accompanying the STC for Polyfiber allow for clips, PKs, or stitching according to the documentation provided with their products. Have I missed something?

[n2582d]

If restoring your wings doesn't work out you might consider making a deal with this guy in Spokane.

[Bruce Fenstermacher]

We were simultaneously typing, Bruce.
The instructions accompanying the STC for Polyfiber allow for clips, PKs, or stitching according to the documentation provided with their products. Have I missed something?

I'll review that document George. I had never considered changing the method of attachment from that used originally so I never looked that close but assumed the STC allowed any attachment method that was originally approved by the manufacturer.

For example on a Piper Cub the rib stitching is an integral part of the wing system structure. Using any other method would compromise the system.

The devil is in the details. We'll have to inspect the STC more careful to confirm the correct answer.