Another point of discussion is priming. There is a wide range of opinions out there. Ex-Navy Air-framers will tell you to use Alodyne, then prime with chromate primer, or the airplane will fall out of the sky after a year of operation! Some very experienced airplane builders will tell you it is all a waste of time as 2024 alclad does not rust/corrode and the primer just adds a bunch of unnecessary weight. What is the truth? The debate rages on......
After a little research, I decided to split the middle! I would prime all areas where there is metal on metal contact. I used a gray metal etch primer made by SEM. It is widely considered a chromate suitable sub and looks better than the Mil-Spec chromate green. I will only use Alodyne in the most critical areas, such as the wing main spar. Using this method, I hope to only add 10 pounds to the airframe in primer, while providing adequate protection for 20 to 30 years of operation. I have heard horror stories of builders adding up to 50 lbs. of weight in primer. I most certainly want to avoid adding that amount of weight.
Process:
1. Abrade with Scotch-Brite pad. 2. De-grease with Prepsol (PPG Product) 3. Heavy primer on flanges (two coats) 4. Light pass on the rest (one coat)
