During this phase of construction it was necessary to assemble the wings to the fuselage for a number of reasons including drilling the rear spar/center section attach, finishing the aileron and flap control mechanisms, installing the wing tank/fuselage attach brackets, fabricating and fitting fuel & vent lines, and installation of wing root fairings.
Before installing the wing, I marked on the W-704 the screw locations at each unused rivet space on the bottom flange of the W-710 root rib. I then marked a straight line from the hole location toward the wing tip and made a measured mark 3” outboard from the intended screw location. This allowed me to measure back to the same point on the overlapping F-776 fuselage skin.
Since my shop dimensions were such that the aileron pushrods could not be inserted from the tips of the wings, the W-716 pushrods had to be loosely placed in the wing lightening holes from the root before the wing panels were “plugged-in” to the fuselage.
Actual installation of the wing panels turned out to be very simple, as the spars had been fitted and drilled at the factory. It was helpful to file a slight bevel on the root ends of the spar to assist getting it started sliding through the slot in the fuselage bulkhead, and to prevent it from scratching and galling the bulkhead bars as it slid through. I supported the inboard ends of the wings when inserting to prevent the bottom of the spar from dragging along the inside of the fuselage bottom skin. As the wings were pushed in near center, I made sure that the fuselage center bottom skin (which overhangs the fuselage) didn’t catch on the wing skin. When bringing the spar into its exact position, lining up the bolt holes in the bulkhead and spar, it was helpful to use drift pins. These were made from hardware store bolts with the ends rounded and tapered on a grinder. Gently driving this lubricated pin into a nearly aligned hole centered the bulkhead/spar hole so that the bolts could be installed without excessive force. I followed the recommendation that 7/16” and ¼” hardware store bolts be used for test fitting to prevent damage to the holes and NAS bolts. I installed the bolts as called-out on DWG 11. For fitting purposes, it was only necessary to install four 7/16” bolts, one top and one bottom for each wing panel. Of course, when permanently installing the wings all the bolts called-out on DWG 11 must be installed.
NOTE: When installing the wing for the last time, I will lubricate the NAS bolts with LPS #2 (available in a spray can). I will not lubricate the threaded portion of the bolt as this would influence the torque wrench reading.
Time: 4 hours.
Leonard's RV-7A Build 