Did the old timers primer the 4130 tubing?

W

way_up_north

Builder
I’m all for primer and protection...but I’m curious about this

From what I’ve heard Cessna didn’t put any primer at all on thier aluminum parts..don’t know about today...

even zenith today only primers at the joints only...

were the older planes built with 4130 tubing..primered back then?...just curious...
 
I'd have to think they were at least zinc chromate or similar at a minimum. Aluminum is more naturally corrosion resistant than steel. It oxidizes in a hurry if untreated.
 
I don't think I'd take anything Zenith has done in the past as guidance for anything. Not the greatest record on those.
The early Cessnas were not zinc chromated, and a lot of those don't exist anymore and the ones that do tend to have corrosion issues.
My 52 pacer had all the tubing painted. We're a bit wet were I live, but some other kits out there use steel bushings that are not protected, and it only takes about a month for those to be covered in spotty surface rust. Doesn't really inspire confidence in the long term.
 
People used to go to the barber shop to be bled, as a cure for ailments. Cars used to not have seatbelts. A great advantage of our airplanes over similarly-shaped old TC airplanes is that they are new, and that they are built with techniques that are the best we know, hopefully. We use synthetic fabric that is not removed frequently like the old cotton. Those tubes might be burried under expensive fabric and paint for 3 decades, which makes me want to give them the most durable treatment they can have.
 
jaredyates said:
People used to go to the barber shop to be bled, as a cure for ailments. Cars used to not have seatbelts. A great advantage of our airplanes over similarly-shaped old TC airplanes is that they are new, and that they are built with techniques that are the best we know, hopefully. We use synthetic fabric that is not removed frequently like the old cotton. Those tubes might be burried under expensive fabric and paint for 3 decades, which makes me want to give them the most durable treatment they can have.
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To that, I love powder coating until it's time to weld on it.
 
I didn't see powder coating as a better solution than an epoxy primer over sandblasted tubing, for this and several other reasons.
 
jaredyates said:
People used to go to the barber shop to be bled, as a cure for ailments. Cars used to not have seatbelts. A great advantage of our airplanes over similarly-shaped old TC airplanes is that they are new, and that they are built with techniques that are the best we know, hopefully. We use synthetic fabric that is not removed frequently like the old cotton. Those tubes might be burried under expensive fabric and paint for 3 decades, which makes me want to give them the most durable treatment they can have.
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Whats the general opinion on storage of the Bearhawk outside yearound?...can the fabric exterior standup?
I’m a complete noob to tube and fabric...
 
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Repeating what I have emphasized before, steel tubing not only needs a good primer, but also a topcoat, that is true for paint or powdercoat. To do anything less on a new steel tube fuselage would be ridiculous. All primers are porous. My 1977 Maule which I bought in 85 already had serious rust showing through the zinc chromate primer. By 91 I decided it had to be dealt with. Pulled all the otherwise good fabric off it, sandblasted, primed and top coated before recovering. That and a few mods took me nearly two years that I wasn't flying.
 
rodsmith said:
Repeating what I have emphasized before, steel tubing not only needs a good primer, but also a topcoat, that is true for paint or powdercoat. To do anything less on a new steel tube fuselage would be ridiculous. All primers are porous. My 1977 Maule which I bought in 85 already had serious rust showing through the zinc chromate primer. By 91 I decided it had to be dealt with. Pulled all the otherwise good fabric off it, sandblasted, primed and top coated before recovering. That and a few mods took me nearly two years that I wasn't flying.
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Is Epoxy primer a primer and top coat/sealer? Combined?
 
zkelley2 said:
Yes. Zinc chromate is generally not used anymore in favor of epoxy. It's one application.
Zinc chromate is also super toxic.
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This isn’t necessarily true. Almost every epoxy primer requires a top coat. I found a few that the specs said a top coat wasn’t required but when I called the manufacturer I found that it made very little sense to not top coat them. None of them were UV stable which means they would yellow and eventually breakdown enough that corrosion could start. And I really really wanted to not have to top coat.
 
Aeronca's had a primer on the tubes. Seaplane versions also oiled the inside of the tubes with boiled linseed oil. American Champion currently powder coats their fuselages. I am in favor of epoxy primer with a topcoat which preferably should be applied within 48 hours of priming for best bonding.
 
No it is just a primer, definitely a better primer than zinc chromate. For interior aluminum pieces it is all that is needed.
 
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The Polyfiber rep I spoke to convinced me not to top coat their EP-420 primer. Said it would not make any difference on interior parts. I was skeptical at first, but wanted to avoid top coat if possible. I sprayed more coats of primer then is typically recommend though.
 
There are two types of primers sealing & non sealing. Non sealing primers MUST have a top coat applied. I can not imagine going to all the trouble of building an airframe & not understanding how to protect it from corrosion. This subject is important. imho
 
I am using Endura EPC-2 sealing primer ! as well as a epoxy top coat ! To protect my fuselage externally.
The product is available in USA through Polyglass Coatings Limited.

Internal protection will be boiled linseed oil. As well as a vacuum applied on the entire fuselage. Monitored with a vacuum gauge in the cockpit.
No way I am going to all the trouble to building a awesome aircraft like BH & then have it screwed up because I never took the threat of corrosion seriously.
 
Protective coatings were an option on my 1977 Cessna. Mine did not have that option, however some of the major fittings in the gearbox and the wings were coated. The issue with any coating is using too much and adding weight. The major airframers go to extraordinary lengths to control film thickness'. On Boeings, we measured the film thickmesses in microns. Some parts looked like they had no coating at all but were well protected. What ever coating you use, be aware of how much your using. Primer is heavy. As for a Bearhawk sitting outside, mine will. The biggest issues for any airplane stored outside is drainage, venting and UV protection. Flying the airplane often to dry it out is vital. Lots of planes sitting outside here in Seattle with T hangers at $750-$1,500/mos.
Gerry
Patrol #30
 
I agree, BearHawks are as top of line bush aircraft as there is. After building my B wings. They are very much under valued imho
 
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