TIP SHEETS Air-Tech Fabric Covering Process The following attempts to answer some of the most commonly asked questions concerning the Air-Tech process. Of course the procedures in the manual control the process but these can be additional help. We hope they help you be even more successful with our products and your aircraft projects. 1. Surface Preparation a. Aluminum – Please follow recommended procedures using acid etch cleaner, alodine and two part Air-Tech epoxy primer. Zinc chromate primer will not work. b. Steel – Sandblast or clean thoroughly and coat with two part Air-Tech epoxy primer. c. Wood – Use only catalyzed Air-Tech polyurethane varnish.
Do not use hardware store “Polyurethane” or Spar varnish as glues etc. will lift them. 2. Fabric a. Blanket versus Envelopes – This is the customer’s option. With the new fabrics 70 inches wide we use the blanket method almost exclusively. b. Fuselage Envelope? – For fuselages with permanent vertical fins we sometimes sew a blanket with the backbone or spine sewn in. However on fuselages we always put on the belly piece last; this is the first to be damaged and it can be easily replaced by using this approach. c. Weight of Fabric – We recommend the following: a. Spray planes or large planes (DC-3) use the 3.7 oz. b. Std. Cat; exp.; aerobat.; etc. – 2.7 oz. Or a combination ie. 3.7 oz.
On belly, elavator etc. c. Ultralights – 1.7 oz. Or a combination. The weight of the Air-Tech coating system is less than any other so heavier fabrics can be used with no comparative weight penalty. 3. Application of the fabric a. For new users always start with a small part i.e elevator to learn the process. b. One of the most common errors is the use of too much adhesive (UA 55 Rev. 1). Keep the glue thin by adding thinner (RA 4000 Rev. 3) to compensate for evaporation. Remember a thin bond is typically stronger than a thick one. c. Always coat all surfaces which will come in contact with fabric with two coats of thinned adhesive.
This especially includes leading edges , turtledecks, ribs etc. d. Be neat and tidy with the glue; this will make for a better finish job. 4. Shrinking the Fabric a. Follow procedures paying close attention to temperatures. b. Use only a clothing iron (1100 watts) for shrinking in open bay areas. Heat guns are too difficult to control. c. Use a small Teflon coated iron or heat gun to eliminate wrinkles or puckers around edges etc. d. Shrink the fabric as tight as the structure will allow. A good fabric job is a tight one. Also remember Air-Tech coatings have no tautening properties. 5. Mechanical Attachment a. Follow manufacturer’s specification and AC 43.13 when applicable. b.
For rib stitching use Air Tech’s FAA/PMA approved flat woven rib lacing. 6. Surface Tapes a. Apply the surface tapes using Air-Tech FAA/PMA approved UA 55 Rev. 1 Adhesive per the recommended procedure. b. Pay close attention to detail and cleanliness when applying the tapes. The idea is to have them on perfectly prior to the application of any coatings. Iron the tape edges per Air-Tech procedures to ensure that all edges are flat. Do not use too high a temperature as it will shrink the tape. c. Glue ridges or drops should be removed by wetting them with MEK until soft and wiping them off with a clean cotton cloth. They will show through if not dealt with.