The International Cessna^® 170 Association

when a fabric wing is metalized with a 337 field approval, what does that involved? I mean, what is the process of a wing made for fabric being converted to metal?
thanks...albert

good luck with a field approval.

This queston is more complex than you may realize.

The "field approval" process is one in which an authorized inspector approves a modification to an airplane that has been inspected and determined to meet existing airworthiness standards, or their equivalent, for a specific airframe. It can be thought of as a "one airframe STC" that was authorized by the inspector. The inspector assumes a great deal of responsibility for that signature, and although once frequently encountered, in todays legal and regulatory environment, it's become much more difficult.

The metalizing of fabric wings refers to a process that removes the fabric, inspects/repairs/alters the underlying structure, and then replaces the fabric with sheet metal which is attached to the original structure, usually with rivets, screws, or clips. The intent is to add durability/longevity to the skin, however with modern fabric processes it has less desireability than it did in the past. (It also makes it difficult to inspect the interior wing structure as thoroughly as is possible with fabric.)

Most metalized wings are so-altered in accordance with STC's, which have blanket approval for the airplanes named in the STC.

Thank you for the insight. The 170 I am considering is a metalized wing which had a field approval around the early 50's. I didn't know if the wing itself needed to be altered. A rag wing Luscombe cannot be metalized because the wings were built differently with different washout, ect. I knew that Stinson 108 Voyager's had wings metalized at the factory and in the field. I am just a real newbie with the 170's.

If I were considering the 170 you are looking at I would inspect the wings very closely for workmanship and what information you have as to how it was done.

Chances are you will have no information available as to the actual process and therefor there will always be a question. Is it right? How do I repair it if need be?

In my opinion there is little advantage today of metal over fabric and being a conversion detracts from the value of the plane.

Doesn't mean it's not a good plane just not as good in my judgement as an otherwise duplicate original finished example.

N9149A wrote:...Doesn't mean it's not a good plane just not as good in my judgement as an otherwise duplicate original finished example.

I knew he'd eventually cross over to my side!

gahorn wrote:[q I knew he'd eventually cross over to my side!

Yet by cutting large gaping holes in the leading edge of your right wing and left side of your fuselage you have gone the other direction. Oh how the pendulum swings.

I've been terribly despondent since our own guru of originalty, "for all the right reasons", fell off the wagon with such a grand splash. If he winds up buying a set of C-180 landing gear legs, I'm going to put my head in the oven.


Wait! Oh hell, Iforgot. I have an electric stove.

blueldr wrote:...guru of originality "for all the right reasons", ....

OK, now...you've at least got to get my motto right! It's NOT that!

Oh BL how you make me laugh.

George I haven't crossed over to anyones side. I still own two very modified aircraft.

I have always recognized that depending on the mod, how the mod is accomplished both on paper and mechanically, and how reversible the mod is will vary the value of that aircraft differently in many peoples opinion. Depending on your view point of the mod itself, will change your value of the aircraft. The modified space shuttle 747 has very little value to anyone but the space shuttle program. Doesn't make it a bad plane.

People new to aircraft need to understand this relationship so they can so that they can develop an educated viewpoint and buy a plane they will be happy with.

I know even being from Texas, you feel the same way.

I was only kidding, of course.... we both recognize, I am sure, that the reason I am fond of originality is that it usually carries a premium value for knowlegeable aircraft purchasers. Highly modified (especially one-off mods) aircraft have narrow market-appeal for most potential purchasers. Therefore I usually recommend that aircraft be kept as original as possible, within reason, commensureate with the intended purpose/use of the aircraft.

My motto is purely as a gentle reminder of that generality. (A ragwing with a Franklin 220, vortex generators, 185 landing gear and 206 seats and metallized wings.... is going to have a very narrow market-appeal when it comes time for the owner/modifier to sell it hoping to retrieve his investment.) That's all I'm saying.

And I was just appreciating the humor in your obvious parallel. (plus it was a great time to show the fantastic emoticon I've been waiting for the opportunity to use.)