ESP47
Well-Known Member
Hey bud what method did you use for prepping the trunk with all its nooks and crannies? Looks great.
Freds 73 Scamp restore on a budget
- Thread starter Frodee
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Hey bud what method did you use for prepping the trunk with all its nooks and crannies? Looks great.
Well after taking the under coating off with oven cleaner and a razor blade I used this for most of it.
Pictures are worth a 1,000 words. I used a sharp chisel to remove the seam sealer and sanded the tight areas with 80 grit by hand. Fingers still sore. lol
txstang84
Well-Known Member
man, I know they are!
Doing the fenders now will post some pics soon I hope.
I will use cavity wax on the inside frame rails and any other concealed spot best I can.
Every plane part we build is painted with DEFT brand paint, it is a mil spec paint, if I remember tomorrow I can get the mil spec numbers.
It is pretty much industry standard, lightweight paint, that holds up to elements and corrosion.
Sounds good thanks, not much of a plane painter at all.
I know the paint is super thin, it takes alot of coats to cover anything.
I was given 7 gallons of primer at work that had expired.
I used a little out of one can to prime the door hinges on my duster, I must have put a dozen coats on to cover them.
Gave the rest of the paint away, it was not worth effort.
Also most are water based now, so dry time is slow.
moparmat2000
Well-Known Member
Akzo noble 512x310 high solids impact resistant urethane compatible light grey epoxy primer is what I get out of date from work. Its an Aircraft primer with a 1 to 1 mix. Clean your paint gun out with MEK quickly afterwards. This stuff drys like ******* concrete. Covers well in 3 coats. Is also sandable to put a high build blocking primer over it.
I have know idea why paint has to be so light weight on a plane.
My idea was to strip the paint on the plane with chemical stripper then clean the aluminum with a scratch pad and prep solvent then epoxy prime and single stage paint.
I know to stay away from sanding on rivets from the little that I know but what do you guys think does that sound right? And will check on paint from the local PPG rep.
My idea was to strip the paint on the plane with chemical stripper then clean the aluminum with a scratch pad and prep solvent then epoxy prime and single stage paint.
I know to stay away from sanding on rivets from the little that I know but what do you guys think does that sound right? And will check on paint from the local PPG rep.
moparmat2000
Well-Known Member
It's pretty simple actually. Everything has weight savings on an aircraft. The more it weighs total, the less useful load weight it can carry. Think about the weight of a gallon of paint and a gallon of primer, times however many gallons of paint and primer just to paint an aircraft. That's the main reason they strip them to bare metal when repainting them.
The main reason American Airlines had polished silver jets and just had the wings painted grey and of course the red, white, blue stripes on the fuselage. It saved weight having polished skin instead of paint.
Imagine how many gallons of paint and primer to paint an entire Boeing 747 400 series. Now imagine the weight of all that paint and primer.
Some aircraft when fully loaded with people, baggage, and full tanks of fuel, exceed their landing weight until enough fuel is burned off while flying. These aircraft are equipped to jettison fuel overboard in the event of a major issue requiring them to land right after takeoff. So they dump fuel to get the weight down within landing limit so they can do an emergency landing.
The main reason American Airlines had polished silver jets and just had the wings painted grey and of course the red, white, blue stripes on the fuselage. It saved weight having polished skin instead of paint.
Imagine how many gallons of paint and primer to paint an entire Boeing 747 400 series. Now imagine the weight of all that paint and primer.
Some aircraft when fully loaded with people, baggage, and full tanks of fuel, exceed their landing weight until enough fuel is burned off while flying. These aircraft are equipped to jettison fuel overboard in the event of a major issue requiring them to land right after takeoff. So they dump fuel to get the weight down within landing limit so they can do an emergency landing.
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moparmat2000
Well-Known Member
After you clean the aluminum. Before you primer it, you need to etch and seal the aluminum with a chemical conversion coating. Either Alodine, or PreKote. Then add your primer and topcoats. Yes, stay away from the button head rivets. Guys like me hate having to drill em out and replace them when painters sand em flat with a DA sander.
Would guess on a small plane that would make the same amount of difference.
Good point.
So if I use the Alodine or preKote I don't need epoxy primer just regular primer? or will sealer work instead of primer?
Sorry for all the questions but I really like knowing what to do before I screw up.
moparmat2000
Well-Known Member
Yep, and even more critical on little aircraft like 2 seat prop trainers like cessna 150s and piper Cubs etc. since theres less wing surface and less fwd thrust to create wing lift.
moparmat2000
Well-Known Member
Still use the epoxy primer. All the alodine does is create a thin anodizing etch to the metal. But it does have chromates in it. Kinda toxic to work with , and has to be rinsed with water, adding to the toxic hazard.
The industry is now going with a non toxic product called PreKote to replace alodine. You basically spray it on the bare aluminum, and lightly scrub it with a fine scotch brite pad to agitate it for about 10 minutes, then rinse with water, and reapply a second time. After the second application of Prekote, sufficient dwell time and a thorough water rinse, you do a water break test. The water will try to pull away from a prekote treated surface. Not like water beading up on paint, much more subtle, but the water does try to pull away. This means the aluminum part is coated. This product is as strong as Alodine in preventing surface corrosion on aircraft skin, and is not toxic. You still want to epoxy primer over it to protect the metal well.
Also make sure your chemical paint stripper is thoroughly neutralized before even messing with anything else.
We had a fleet of SAAB 340B airliners that a paint shop contracted to do mtx on. They neglected to fully neutralize the chemical stripper on 2 aircraft but didnt remember which ones. The stripper kept eating the aluminum under the new paint. We had to bring in every one of em several different aircraft each day, and strip squares of paint in key locations on each aircraft inspecting the skins until we found the 2 aircraft in question. We ended up stripping them of useful parts and scrapping them.
The industry is now going with a non toxic product called PreKote to replace alodine. You basically spray it on the bare aluminum, and lightly scrub it with a fine scotch brite pad to agitate it for about 10 minutes, then rinse with water, and reapply a second time. After the second application of Prekote, sufficient dwell time and a thorough water rinse, you do a water break test. The water will try to pull away from a prekote treated surface. Not like water beading up on paint, much more subtle, but the water does try to pull away. This means the aluminum part is coated. This product is as strong as Alodine in preventing surface corrosion on aircraft skin, and is not toxic. You still want to epoxy primer over it to protect the metal well.
Also make sure your chemical paint stripper is thoroughly neutralized before even messing with anything else.
We had a fleet of SAAB 340B airliners that a paint shop contracted to do mtx on. They neglected to fully neutralize the chemical stripper on 2 aircraft but didnt remember which ones. The stripper kept eating the aluminum under the new paint. We had to bring in every one of em several different aircraft each day, and strip squares of paint in key locations on each aircraft inspecting the skins until we found the 2 aircraft in question. We ended up stripping them of useful parts and scrapping them.
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Thank you you've been a big help in what I need to do on painting the plane.
Better go buy some of the chemical stripper now Fred (if you can) they took the good stuff out (methylene chloride) because It was draining the gene pool of idiots that didn't read the directions. I haven't found anything to replace it yet. I think the magic date is Sept 15 it cant be on the shelves for consumers.
Ho **** I will BP heading to buy some now. I don't know any better way to strip a plane.
Thanks for the info.
Picked up 2 gallons of stripper, not cheap 42 bucks a gallon but cheaper than sand paper and filling down a pile of rivets. Thanks again BP.
In addition to total weight, there's also a balance issue for all aircraft.
I spent a lot of years in the aerospace industry and the final few years were spent in sales and marketing of portable electronic aircraft scales.
All aircraft have to be weighed every few years to verify the center of gravity (CG) is still within the specified envelope. Every change made to the aircraft can effect the CG - seating layouts, re-engine, paint, instrumentation, weapon loads, etc.
For instance, the CG of an F-16 has to be within a 16"-long envelope along the centerline of the aircraft. Helicopters are also especially critical.
moparmat2000
Well-Known Member
We jack and level the ones we work on after heavy check. Theres a spot to tie off a plumb bob to the inside from the ceiling, then it gets jacked and leveled to a specific spot location on the structure. When the plumb Bob points dead center on that specified spot, the aircraft is then level. Then we take and record the readings from the load cells at all 3 jacks. Theres a left weight, s right weight, a nose weight, and a total weight.
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