[aarvig]

We just sold our house and are planning on building a new one. Unfortunately, the airplane project is going to get put on hold for at least a year while this process gets settled out. I have built the tail section and the rear spars for the wings. The main spar and ribs have all been drilled and countersunk. I am primarily concerned about corrosion on the main spar where it has been countersunk and drilled. Do you recommend just coating the spar with my standard Napa 7220 to safeguard against corrosion or should I alodine it with an alodine pen? Any thoughts as to the effectiveness of those pens? I know they are expensive but it is the wing spar. Thanks for your help.

 

[fixnflyguy]

Spar preservation

It wouldnt hurt to use a Q-tip and prime the spar "drill holes" and countersinks. In fact, unless you have a Phlogiston spar (anodized) it wouldnt hurt to prime the whole thing. I primed every piece,every side, and all the holes during spar build. Use some good epoxy primer and never worry about it again. The extrusions are not tolerant of moisture,and should be 100% primed. I stored mine for almost 5 years in a garage with no problems.

 

[Dbro172]

Epoxy primer

If I were moth balling my spar I would prime each bit of bare aluminum (countersinks through the anodized) with an epoxy primer such as Akzo Noble, and a Q-Tip. Unfortunately it will cost you about $200 for a two gallon kit, which could do the innards of your entire empennage and wing kits. I wouldn't buy anything from Napa to build my airplane. Der is no shortage of moisture or humidity up der in Minnesota, eh!