painting the wings, UV, etc.

[jim cooper]

question to all paint gurus: When the fellow painted the wings on my airplane, he used very little silver block. So.....when you take off an inspection cover and peer in, you can see lots of creme colored paint! I discussed this with the builder....he said quote", I put silver on but sanded it quite a bit. Its ceconite and dope with lots of dope (creme color) so Its fine. Remember that it was ALWAYS in the hanger! (unquote.) So... you opinions please. (I keep it in the hangar always but it may sit out during a day if I'm flying alot.) I think possibly that he forgot to put silver on at all, or to save money and WEIGHT decided to put extra creme color on instead. The paint job is superb. JC

[Ray36048]

Re: painting the wings, UV, etc.

Sun light is about the only thing that will destroy modern fabrics. If you can see through it from the inside, the sun light is getting to the fabric. The Poly Fiber manual says something about fabric deteriorating in about 6 mos when exposed to sun light. The fabric job was not done correctly.

[jim cooper]

Re: painting the wings, UV, etc.

Its flown 600 hours since it was rebuilt. This tranlates into approx. 75 hours of being in the sun provided all these days were brite sun, alot of them probably were not. He further stated :" I read alot about the covering before I did it. If you punch test it it will show perfect." unquote. I shall punch it when I annual it in April. The covering is tight and looks very good! JC

[Ray36048]

Re: painting the wings, UV, etc.

Is this your first annual since you bought it? If your IA knows fabric, he may not sign it off.

[jim cooper]

Re: painting the wings, UV, etc.

He's 83 years old and has been around fabric aircraft forever. He said if it punches, it passes. He also thinks it will prove OK. Incidentally, I bought a 7ECA from a person near you several years ago that was totally misrepresented. It had had a prop strike. The engine had to be redone. The owner lied. JC

[Ray36048]

Re: painting the wings, UV, etc.

Sent you a PM....

[M Towsley]

Re: painting the wings, UV, etc.

From what I have read, and only read, one does not punch test Ceconite. Just my opinion from what I have read, sooooo.....????? Any other thoughts regarding this. I am curious.

[ajfriz]

Re: painting the wings, UV, etc.

Punch test doesn't apply to ceconite.

[Larry Lyons]

Re: painting the wings, UV, etc.

Ladies and gentlemen why are we discussing this. I am sure there is/are empirical data out there, either from the fabric manufacture or the FAA, as ceconite had to be certified. I am sorry as I have no idea where to start this investigation but I firmly believe the info is out there.
L

By the way I have a 30 year old ultralight that the fabric still tests acceptable because it is always hangared and I have more then one parachute that is well over 30 years old. The fabric still checks out "OK" because the chute is always hangared. (packed of course) By the way neither of these have a single coat of paint!

[M Towsley]

Re: painting the wings, UV, etc.

Larry,

I think it was Jim who asked for everyones opinion as to their knowledge regarding Ceconite and the use of sun blocking silver, or not, and the possible damage that may be involved to his airplane he is attempting to sell.

By discussing it he has so far learned that punch tests may not be a valid test, though his 83 year old A&P believes it may be. I took the time and researched that information again before posting so I would provide that part as possible empirical data as you suggested. I am sure there is more good information to come and look forward to it. My restoration is an older one and the paint and cover look almost new but I am always concerned about aged covering.

[Hank Jarrett]

Re: painting the wings, UV, etc.

Guys,
A punch test actually is testing bearing strength of the fabric while the main load seen is in tension. The reason it has been the standard for decades is the bearing strength of cotton and linen is proportional to its tensile strength and a punch test is non-destructive while a tension test isn’t. I don’t know if the same holds true for synthetic fabric.
When I bough my plane I was unsure of the fabric. It had passed a punch test, but I wasn’t sure if the test actually meant anything and my IA and A&P said it wasn’t needed. I guess you guys know me well enough by now to know I did my own test.
Understand, this test means NOTHING to the FAA. It is not called for or recognized by them, but it made me feel secure that MY fabric was good. My worry was that I have seen synthetic fabric that had deteriorated from UV to the point that I could put my finger through it. I wanted to know if my plane was safe, not if the FAA thought it was safe. There is nothing in the regs that says you can’t inspect anything you want IN EXCESS of the requirements.
Here is what I did.
I cut out some of the unused inspection covers from the top of my plane. There are two rectangular covers over the aileron linkage and one over the trim mechanism on the stab. IF they aren’t cut out, you should be asking how the owners (maybe YOU) have been doing the lubrication of those parts, but that is a different question. You just want the fabric. If you HAVE been lubing your plane, check the access cover over the trim handle. That one is rarely cut out.
Remove the fabric circle and cut it into a few 1.5” wide strips along the strands. If you cut the fabric on the bias you WILL fail the test. You need to test only the TOP layer of fabric, that is the one that will show the most UV damage.
Wind and glue both ends of the fabric around a wood or steel rod so you can grip it to pull the fabric.
Trim the area between the rods so that the fabric is only 1” wide with smooth arcs. Make absolutely sure there is 1” of uncut strands across the test section!
AC 43.13 Para 2-33 says “Fabric installed on aircraft with a wing loading less than 9 lb. per square foot (psf), and a Vne less than 160 mph, will be considered unairworthy when the breaking strength has deteriorated below 46 lb. per inch width, regardless of the fabric grade.” Notice it says FABRIC, not what type of fabric.
Apply the load SLOWLY and evenly across the test secton! This is a tensile test, not a tear test. If you pull one side harder than the other it will tear across the section. If you pull test the sample, and it holds at 46#, the fabric has not deteriorated to the point of being un-airworthy.

Remember. THIS IS NOT A RECOGNIZED OFFICIAL TEST! This is to make YOU feel comfortable that your fabric is still safe. It means NOTHING to the FAA. I just don’t like it when the feds tell me to do a test that doesn’t really tell you anything. I DO their test because I have to, but I develop MY OWN tests to convince myself the plane is safe. There is NO REGULATION against doing MORE tests than required. We had to comply with the ultrasonic tests of the struts even though they DID NOT demonstrate they were good or bad (ultrasonic tests for CRACKS, NOT CORROSION). The FAA STILL has not recognized that a visual, followed by a pull test is less expensive and a better test of our struts. I want to do both. One to make me legal, and one to know my struts are safe.
Hank

By the way, my fabric was still good well beyond 50#.

[M Towsley]

Re: painting the wings, UV, etc.

Hi Hank,

I would take it you used some kind of pull scale to arrive at the actual numbers? Thanks!

[1938BF50]

Re: painting the wings, UV, etc.

Lot's of data available to properly do this test. When my upper wing surfaces barely passed the punch test, I built a fixture to do the pull test. It was purely a curiosity thing for both myself and my IA. I built the lower clamp to accept a 5 gallon bucket. In use the bucket was a couple inches off the ground and we very slowly filled it with water. The 1" wide BARE fabric specimen failed at 31 pounds(combinded weight of the lower clamp, the bucket and the water). I got my jackknife out and slit the wings in several places to easily resolve the covering question. I may have pics of that fixture somewhere on another drive.

[N96337]

Re: painting the wings, UV, etc.

Read the Ceconite manual....not the one you have that's dated 1953 or whatever, but the current Ceconite manual, and it will give you detailed and approved inspection data.
While the punch test is not considered a final "make/break" test, it's an indicator of wether you need to go further. The bare fabric pull test is the accepted standard, and that, along with the other criteria spelled out in the current STC manual is what you base the decision of airworthiness on.
Personally, I've turned down aircraft, on the buying end of things, when they had an "expert" fabric job such as was described at the start of this thread. I've also HIGHLY recommended to others NOT to buy them. Recovering is a big job, and it's hardly ever reflected properly in the price, when done incorrectly.
The fabric on this airplane may last a long time if kept in a hangar and taken care of....but just think of how long it would've lasted if it had been done properly in the first place!! Dope doesn't block the UV rays.
Too many people (mechanics as well as owners) think that a fabric job should be rated top quality if you can't see the weave and tapes, and it's really a nice looking, shiny paint job.... instead of looking at the "foundation" for a properly done job. It's too bad. I've seen jobs that had bad looking topcoats, that outlast the slick looking stuff by ten times. I just shake my head when I see these jobs come through the shop.
In my opinion, the STC wasn't followed properly in the first place... so the fabric is not being properly protected from UV rays. I'd have to sit down and read the inspection criteria closely again in the current manual, to make a decision of wether it's technically airworthy. (I'm at my house right now, and my manuals are in the hangar) If the approved data supports it being an "on condition" thing, I'd first punch it, look at the other conditions spelled out, then go from there.
John

[Pearson]

Re: painting the wings, UV, etc.

Is it permissible to sand the paint down and apply a couple of coats of silver over what is left of the paint, then refinish?