Cleaning and Painting the Engine Mount
When I was restoring my Alon, I removed and either rebuilt or replaced everything forward of the firewall. The engine mount was originally painted with the factory green primer, and had been touched up with various other colors of green primer over the years.
Engine mount prior to removal from airframe.
Engine mount removed from airframe.
I sand blasted the entire engine mount and put two good coats of Poly Fiber green epoxy primer on it. The engine mount looked great when it was done, and eventually it came time to reinstall it on the plane and reinstall the nose gear strut.
Engine mount after spraying it with green epoxy primer.
The plane sat in the hangar that way, without the engine for several months. Then I started seeing a very slight amount of rust starting to show through the primer in just a few places. Further inspection showed that in several hard to get at places, the primer was way too thin, and the steel was rusting through the very light coat of primer.
This problem had two causes (aside from the obvious fact that I didn't do a good paint job!). One was that it is very difficult to get a spray gun in around all sides of every tube that makes up the engine mount. You can spray over and over and think you have it all covered, and continually miss the same areas. Those round tubes have lots of "sides" and coating them all evenly is a real challenge. The second cause is that once you spray the first coat of any color on, you really can't tell where you have sprayed adequately and where you haven't when you put on a second coat of the same color. The new paint looks just like the first coat and you really can't tell what you are doing because the colors are the same.
Needless to say, the nose strut was removed, the engine mount came back off the airplane and the whole thing got sand blasted down to bare metal again. Then I applied a good coat of green epoxy primer, followed by a coat of the same brand of primer in white, and then coated it again in green. By applying a white coat on top of the green coat, it was easy to see where the white coat was thin, because in the thin areas, the green showed through. When everything was a good solid white color, I shot green over it, and again, it was easy to see where the green primer was thin because the white showed through. This resulted in at least two good coats with 100% coverage.
Engine mount reinstalled. Getting ready to hang the engine.
Of course, you need to follow the manufacturers recommendations concerning how long to wait between respraying.
The mount has been on the plane for several years now, and has shown no indications of any rust anywhere.
Disclaimer: Please understand that this info is being offered as food for thought only. I am not a licensed mechanic or an aeronautical engineer and I am not in any way qualified to give technical advice in regard to aircraft maintenance. Please consult a licensed mechanic or aviation professional before using any information that I might provide. (How's that for a disclaimer?)
Hope this info is of some use to someone out there!
''Wayne DelRossi Alon N5618F''