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Permalink Reply by Dan Hill on August 26, 2020 at 6:57pm

Hi Mark:You are going to have to help me out here because I am just some idiot who thinks he can build an airplane, what is fay sealing? for etch primer I use Duplo self etch primer in an aerosol can because I can get it at my local O'Reileys auto parts store where they normally have 2 cans in stock, (they began stocking 3 when I bought 2 at a time) and with that rotation I feel that I always have fresh stock, it is reddily available and I never have to wait for it to arrive altho now I see spruce is selling it. I use it between mating surfaces and along rivet lines. this is all I do as it offers the protection I feel I need and will be a satisfactory base for later sealer and topcoat. some are using cortec sourced from Zenith and some are doing nothing. 

definition of expert-- ex is a has been spert is a drip under pressure. Dan. 

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Permalink Reply by Mark Gregory on August 26, 2020 at 11:18pm

Hi Dan. Thank you for your input. I have learned a lot from you guys in a shot time.

Fay sealing is using sealant (chalking) between the mating surfaces. The sealant prevent condensation, dirt, and electrolytes from getting in-between the mating surfaces; causing corrosion. The sealant also acts as an adhesive and provides shear stability of the structure. The sealant that I plan on using is PS870-C12 (PPG product). I guess I've worked in the aircraft business too long and old habits are hard to break. 

For the primer, I'll properly just use a spray can like you did on the mating surfaces. Not sure if I'll cover all of the surfaces but definitely all inside lower surfaces. I'm open to suggestions.

Best,

Mark

KRYN Tucson, AZ

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Permalink Reply by Dan Hill on August 27, 2020 at 6:43am

Thank you Mark: I assumed it was something similar to that but had not heard the term and wasn't sure. primers are normally a hot topic that gets beatten to death so I was surprised that you hadn't gotten 7 different opinions about what the proper product was and I think most who would have given their opinion weren't sure what the term was.

My opinion is that for the Zenith application it is not necessary to use any further sealants or protection between the mating surfaces. I feel that the etch primer will provide enough protection on 6061 and will prevent any galvanic action which may occur and is not necessary for structural integrity. cortec is being used by many between mating surfaces and is being considered somewhat of an adhesive if assembled while still wet.  Dan

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Permalink Reply by Mark Gregory on August 26, 2020 at 11:16pm

Best,

Mark

KRYN Tucson, AZ

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Permalink Reply by Keith Thomas on August 28, 2020 at 11:58am

Really the only fay surface sealing Id worry about it between steel and aluminum, we are not building 600 mph fighter lol. Even the corporate jets I worked on didn't have faying surface sealing except between steel and aluminum. And on the grounding terminal strips. the only thing I am using between aluminum mating surfaces is the cortec primer we can get for Zenith. I am going to use Pro Seal Fuel tank seal P/S 890 B2 pint can

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Permalink Reply by Mark Gregory on August 28, 2020 at 10:13pm

Thanks for your feedback Keith. I come of the commercial MRO world and everything get sealed in place. Like I said, old habits are hard to break. I was really surprised at the cost of this stuff. C type is especially hard to come by. 

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Permalink Reply by Keith Thomas on August 29, 2020 at 8:18am

I used to work on Lockheeds Stealth and it was 100% sealed as well. and All rivets and fasteners were installed wet.

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