Tuesday, May 8, 2012

Vans Aircraft RV-12 Build, Section 21: Mid Fuse Bibs & Bottom Skins (part 11)

Reference: page 21-17; 3 hours

In this entry we get to play with fuel tank sealant. I just purchased the one ounce container from Van's Aircraft as it does have a shelf life and I didn't want to use old sealant when it came time to build the fuel tank.This stuff can and will make a mess. So think through the process before mixing the sealant components together.

Step 1: Separate the F-1326 Step Attach Angles by removing the hatched areas as show in the RV-12 plans on page 21-17.

Step 2: Make the F-1236B-L & -R Outbd Step Attach Angles by trimming the flanges of two of the angles separated in step 1. (At this point these two parts are identical, but will become left and right once they art drilled in a later step.) The two, remaining, untrimmed angles seperated in Step 1 are designated F-1236A-L & -R Inbd Step Attach Angles.

Step 3: Separate the F-1251 Nutplates Bracket into individual parts by removing the hatched areas shown in figure 3 of Van's Aircraft plans.

Step 4: Machine countersink the F-1251-L & -R Nutplate Brackets for the attach rivets called out, then rivet the nutplates in place.

Step 5: Cleco the F-1236A-L Indb Step Attach Angel to the F-1212-R Step Rib and the F-1236B-L Outbd Step Attach Angle to the F-1212-L Step Rib as shown by Van's Aircraft in figure 4 of the RV-12 plans. Then match drill #30 the indicated holes of the F-1202F Bulkhead into the step attach angles. Cleco the holes, then repeat this step for the right side of the fuselage.

Step 6: Final-Drill 1/4 the hole in the F-1202F Bulkhead and the F-1236B-L Out bd Step Attach Angle that is indicated in figure 5 of the plans.

Builder's note: I completed each step on both sides of the fuselage rather than completeing one side and then going the the other.

Step 7: Temporarily bolt the WD-1233-L Step to the F-1202F Bulkhead and F-1236B-L Outbd Step Attach Angle.

Builder's note: As can be seen in the picture above I used a straight edge to level both steps before drilling them so they would be the same on each side of the RV-12.

Step 8: Make the pad of the WD-1233-L Step horizontal, however, the inbd, top corner of the step is to remain even with or below the beginning of the radius of the F-1202F Bulkhead. See figure 5 on page 21-17 of the RV-12 plans. Once the step is positioned, match-drill 1/4 the inboard hole of the step into the bulkhead and F-1236A-L Inbd Step Attach Angel. Remove the step.

Builder's note: I need to add two washers under the outside edge of the pad and the straight edge jig on both sides to get the upper corners below the radius of the bulkhead.

Step 9: Seal the opening in the WD-1233-L Step with fuel tank sealant.

Builder's note: First fuel tank sealant is sticky and will get over everything. Do wear gloves! It doesn't stick to polypropylene plastic (i.e.sandwich bags) so this can be used to cover the outer surface of the sealant as it cures. Then when it has sets up it will come right off. Also, I primed the inside of the steps with zinc chromate, and allowed it to dry, before sealing them up.

Step 10: Repeat Steps 6 - 9 for the right side of the fuselage. I did both side at the same time.

This completes page 21-17 of the RV-12 plans.