the ribs which will come in contact with fabric with two coats of the thinned adhesive. Note the edges of most fabric are thermally cut which leaves a bead along each edge; this bead must be removed before application. The first length of fabric must be oriented span-wise covering the surface (top or bottom). There must be a fabric overlap of 4 inches minimum at the leading edge and enough to wrap around the trailing edge. Leading edge seams must later be covered with a 2 inch surface tape minimum. Note the minimum fabric overlap for lapped joints other than leading edge is 2 inches. The fabric is secured at the trailing edge using the thinned UA 55 Rev.
1 adhesive by wrapping it around and cementing it to the structure. As the fabric is attached brush a thinned coat of adhesive on the fabric and work it in with the brush or other aid to reactivate the previously applied adhesive and remove any entrapped air. The goal is to totally saturate the fabric. The fabric must then be worked with adhesive toward the leading edge paying particular attention to the aileron bay and tip bows to ensure the fabric is getting full adhesion. The fabric must be kept smooth and straight during this process but not pulled too tight. When this panel is completely attached apply two coats of thinned (2/1) UA 55 Rev.
1 adhesive to all attachment areas and allow it to dry. This will provide a foundation of adhesive for the next fabric layer. Apply the next fabric panel in the same manner taking care to ensure the proper overlaps are maintained. Take great care with the adhesive to ensure there are no unsightly lumps and/or ridges. In areas where the fabric is cut to allow for control cable exit, attachment points etc. make sure the fabric is securely attached with adhesive. After fabric tautening install fabric doublers for greater reinforcement. If any doubt exists as to the strength in these areas it is OK to even apply a triple fabric thickness.
A point of notice is the aircraft manufacturer has precut acetate doublers for these areas to be installed after fabric tautening; consult manufacturer specifications and your parts manual. Option 2: Use of Three Span-wise Lengths of Fabric If one width of the fabric will not cover the wing it is easy to use three pieces of fabric oriented span-wise to complete the cover job. The procedure is the same as option 1 except three span-wise lengths are used rather than two. First, lay a length of fabric out span-wise onto the wing either top or bottom.
Starting at the trailing edge wrap the fabric around the trailing edge and permanently attach it to the trailing edge with fabric adhesive in the same manner as Option 1. Then work the fabric toward and over the leading edge forward of the spar no less than four inches. Repeat this procedure for the other surface of the wing. After top and bottom fabrics are both in place a span-wise length of fabric must be cut which will wrap around the leading edge from the top of the spar to the bottom. Before attaching the leading edge fabric, coat the entire leading edge including the 4 inch fabric laps with two coats of fabric adhesive thinned two to one and allow each to dry for 5 minutes.
The leading edge fabric installation can then be complete in the normal manner paying particular attention to fully saturating the fabric and removing any entrapped air. The fabric must be allowed to dry overnight before the shrinking or tautening process is started. Good planning will ensure the overnight cure is no problem to the flow of work.