Removal of Old Fabric Coverings Preparation of the Airframe Before Covering Removal of the old covering is the first step in replacing  an aircraft fabric covering. Cut away the old fabric from  the airframe with razor blades or utility knife. Care should  be taken to ensure that no damage is done to the airframe.  [Figure 3-16]  To use the old covering for templates in  transferring the location of inspection panels, cable guides,  and other features to the new covering, the old covering  should be removed in large sections. NOTE: any rib stitching  fasteners, if used to attach the fabric to the structure, should  be removed before the fabric is pulled free of the airframe. If  fasteners are left in place, damage to the structure may occur  during fabric removal.  Once the old fabric has been removed, the exposed airframe  structure must be thoroughly cleaned and inspected. The  IA collaborating on the job should be involved in this step  of the process. Details of the inspection should follow the  manufacturer’s guidelines, the STC, or AC 43.13-1. All  of the old adhesive must be completely removed from the  airframe with solvent, such as MEK. A thorough inspection  must be done and various components may be selected to be  removed for cleaning, inspection, and testing. Any repairs  that are required, including the removal and treatment of all  corrosion, must be done at this time. If the airframe is steel  tubing, many technicians take the opportunity to grit blast  the entire airframe at this stage. The leading edge of a wing is a critical area where airflow  diverges and begins its laminar flow over the wing’s surfaces,  which results in the generation of lift. It is beneficial to have  a smooth, regular surface in this area. Plywood leading edges  must be sanded until smooth, bare wood is exposed. If oil  or grease spots exist, they must be cleaned with naphtha or  other specified cleaners. If there are any chips, indentations,  or irregularities, approved filler may be spread into these  areas and sanded smooth. The entire leading edge should be  cleaned before beginning the fabric covering process.  To obtain a smooth finish on fabric-covered leading edges  of aluminum wings, a sheet of felt or polyester padding may  be applied before the fabric is installed. This should only be  done with the material specified in the STC under which  the technician is working. The approved padding ensures  compatibility with the adhesives and first coatings of the  covering process. When a leading edge pad is used, check the  STC process instructions for permission to make a cemented  fabric seam over the padding.  [Figure 3-17] When completely cleaned, inspected, and repaired, an  approved primer, or varnish if it is a wood structure, should  be applied to the airframe. This step is sometimes referred  Figure 3-16.  Old fabric coverings are cut off in large pieces to preserve them as templates for locating various airframe features. Sharp  blades and care must be used to avoid damaging the structure. 3-14 Gently roll the fabric back as the cut is made. Carefully cut away the fabric.