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Bottoms Up! The false spars are installed with the wing bottom facing up. It is the easiest way in which to start the installation and helps assure a good job. The wing would be placed on a good set of saw horses that are reasonably level and support the wing assembly on the front and rear spars. It is a good idea to lay out each false spar in its appropriate position insuring that each is of adequate length to properly lap when joined, and that the lap joint is on a rib. It is possible to start with the wrong piece and not have the overlap fall on a rib. There are normally two false spars per wing. The J-3 wood spar and J-3 metal spar are different lengths because the wood spar wing has one less rib causing the lap joint to be in a different location. The metal spar J-3, PA-11 and PA-18-95 thru 135 are the same. These models utilized the "cove" style false spar as shown in Fig. 10. It is attached to the rib tails and false spar supports as per Fig. 1 and Fig. 2. The false spars are end notched as detailed on Fig. 10 to fit the rib profile at the attach point, and can be used on either right or left wing assemblies. The aileron hinge cut-out shown in Fig. 10, will have to be made which allows the aileron hinge to pass through. The PA-14 and PA-18-135 thru 150 are again different because a flap false spar had been added ahead of the flap assembly. The PA-12 and PA-14 have the "flat" style false spars, Fig. 11, and are similar to that of the PA-18 flap area. They are installed onto the rib tails as per Fig. 6. It should be noted that while #4PK screws were used to secure the false spars in the aileron areas, the flap false spars are secured with #6 machine screws as indicated in Fig. 6. The inboard tank bay false spars used on the PA-14 and PA-18 were the "full wrap" style, Fig. 12, and extend up to and attached to the inside face of the top cap on the rear spar. Figures 3, 4, and 5 show how the aileron flap hinges extend through the false spars. Note on Fig. 5 that a reinforcement must be added to the inside surface at the inboard flap hinge. This reinforcement, DC12028 is riveted in place and reinforces the double holes at the flap bellcrank detailed in Fig. 11. Figure 8 shows the correct location of the PK screws with respect to the rib cap strip, and Fig. 9 shows how the false spar needs to be flattened where the offset bend intersects the rib. Figure 7 demonstrates how the aileron or flap hinges can be aligned with a straight edge before the hinge clamp rivet holes are drilled. Double check - double check - triple check to make sure all screws are tight, rivets are properly set, and all components are in their proper place! |
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