Submitted by Bob Buckihul
In preparation for wing closing, I scrubbed out the fuel tanks with water and Simple Green. After lots of scrubbing and suds, I turned the hose on and flushed everything out the drain holes in the center. About half an hour later when the surface moisture had dried, I was stunned at the amount of water still in puddles trapped behind baffles and in smaller irregularities created by MAT fibers where the main spar is attached to the lower skin.
My wing is being assembled under a patio cover in my back yard. Therefore, I have the luxury of hosing it out to remove debris. I have now smoothed the channel between the spar cap and lower skin and I have opened up the baffles so that they don’t block the channel. I have also re-contoured around the sump to create a channel for water flow.
For builders who can’t turn on the hose, a pint of water poured above the H rib and collected with a bucket under the sump drain is enough to check for water traps.