Who Did not Prime Internal Parts

First post, getting -10 Tail in August. I have read a lot about primers the last few weeks. Just want to get the input from those who have not primed internal parts and like me do not live near salt water. No regrets? Regrets? How is your airplane now?

My 1955 C180 is unprimed and has little corrosion. It spent most of its life in arid climates. The light corrosion that I can find came from 6 months when it was tied down near Philadelphia.

The key here is the arid climate. Another factor is resale. As a result, I'm priming my RV-3B throughout, even though while I own it, it'll live in the arid Colorado area in an insulated hangar.

Dave

To prime or not to prime.....

FletcherLynd said:

First post, getting -10 Tail in August. I have read a lot about primers the last few weeks. Just want to get the input from those who have not primed internal parts and like me do not live near salt water. No regrets? Regrets? How is your airplane now?

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I worked as an aircraft mechanic in Montana for years and we saw many aircraft (factory-made) with the "snow" of corrosion. Montana is also arid and corrosion not much of a problem there. Most of the aircraft we saw with problems were from humid states. I had seen enough that it prompted me to prime the interior of SuzieQ with no regrets. I am also in Colorado where she lives in an unheated hangar. It is refreshing to look inside her and see primer. It doesn't need to be a thick coat. I am +1 for priming the interior..... I guess I would say: "why not?"

Photo: interior of SuzieQ (where I recently have spent some time working....this is a picture of my Feline Assistant!). This is an 'RV Grin' of another kind.....

I did not prime the interior of my RV-14 as I have plans to keep it for a long time and my hangar is heated. If you plan to leave it outside, I would prime. My float plane will see water so I primed that one. I chose not to prime for the weight savings. A little weight here and a little weight there add up quickly.

Years ago Scott McDaniel did a “under the outside stairs” primer test at Vans.
He put unprimed Alclad and Alclad primed with P60G wash primer under the stairs and left them there for a while. The unprimed pieces corroded, the P60G held up well.
SW doesn’t suggest P60G as a good corrosion inhibitor and recommends top coating. However, it seems to do very well on Alclad.

I primed all interior pieces with P60G. I didn’t prime baffles. My airplane has always been hangared, 15 years inland and the last three on the Coast. My interior looks like new, as I just witnessed scoping the HS for SB. The bare unprimed baffles always showed a bit of mild corrosion, not much but a few light spots here and there.

P60G weighs almost nothing. I would consider it a minimum amount of protection and it has done well for me. You don’t necessarily need to top coat with a two part epoxy unless you feel you need the ultimate in protection.

Test

No dog in this hunt because I primed the interior with P60G2 and alodined the exterior.

I do have three test parts outside. They've been outside for years. It's a test of vinyl, but none have corrosion.
One is bare Alclad. One is Alodined. One is P60G2.
All three have been exposed to Colorado sun, rain, snow and even bouncing down the gravel driveway due to our crazy wind.
Someday, the plan is to trim off a strip to see results.
-will it come of
-difficulty
-condition of the metal underneath

No primer war..but I'm all about priming

43 years in the aircraft overhaul and maintenance, mostly heavy jet, where there is no bare metal, period. I built my RV-4 with 100% prime from the beginning, all BAC spec 2 part fluid resistant green. Its impervious to near everything and almost impossible to remove. For the skin internal surface I overthinned it and rolled it on with a smooth foam roller. All the frames and such are sprayed. I even swabbed all the holes for bolts with Q-tips during assembly. I spent 10 years in the Boeing/Airline aging aircraft and corrosion protection steering group, so I became obsessed you might say. I'm also an AP/IA in he GA world an have seen my fair share of corrosion and bare innards..nothing against it in the right environment, I'm just a "primer advocate".

There's no one-size-fits-all answer. I looked at an RV-8 at the weekend that was built in Texas 15 years ago and has been in England for the last 6. But it lives away from the coast in a hangar. No prime on the alclad and no corrosion. I've seen others that live in damp hangars that have corroded.

Does anybody have experience using a corrosion inhibitor like Corrosion X on a plane that didn’t have the internal parts primed during construction?

rv9builder said:

Does anybody have experience using a corrosion inhibitor like Corrosion X on an a plane that didn’t have the internal parts primed during construction?

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CorrosionX is a great product…HOWEVER…do not use it if you intend to paint the parts later.

My Dad built his RV8 in 1998-1999. He didn't prime it because in his words "it will outlast me." I had to reskin the rudder a few years ago due to some ground damage, and found corrosion underneath the stringers. Airplane has always lived in a hanger in Wisconsin.

Turns out Dad was correct ( he passed in 2019) but it likely won't outlast me. I would prime everything if I was building one.