This section deals with the materials and procedures to be used in repairing reinforced plastic and sandwich construction components. The procedures discussed are general in nature. When actually repairing reinforced plastic and/or sandwich construction components, refer to the applicable maintenance instruction manual or structural repair manual.

The repair of any damaged component made of reinforced plastic requires the use of identical materials, whenever they are available, or of approved substitutes for rebuilding the damaged portion. Abrupt changes in cross-sectional areas must be avoided by tapering joints, by making small patches round or oval instead of rectangular, and by rounding the corners of all large repairs. Uniformity of thickness of core and facings is exceedingly important in the repair of radomes. Repairs of punctured facings and fractured cores necessitate removal of all the damaged material, followed by

During installation of the panel, remove each screw from the cardboard and reinstall it in the same hole from which it was removed until all of the screws are reinstalled. If any screws or other fasteners are damaged during removal or reinstallation, the part replaced must be the same part number as the damaged part. Some fasteners are required to be of nonmagnetic material because of their location near compasses and other instruments. The specific part number for each fastener can be found in the IPB for the aircraft.

This section deals with the materials and procedures to be used in repairing reinforced plastic and sandwich construction components. The procedures discussed are general in nature. When actually repairing reinforced plastic and/or sandwich construction components, refer to the applicable maintenance instruction manual or structural repair manual.

The repair of any damaged component made of reinforced plastic requires the use of identical materials, whenever they are available, or of approved substitutes for rebuilding the damaged portion. Abrupt changes in cross-sectional areas must be avoided by tapering joints, by making small patches round or oval instead of rectangular, and by rounding the corners of all large repairs. Uniformity of thickness of core and facings is exceedingly important in the repair of radomes. Repairs of punctured facings and fractured cores necessitate removal of all the damaged material, followed by replacement with the same type of material and in the same thickness as the original. All repairs to components housing radar or radio gear must be made in accordance with the manufacturers recom-mendations.

This information may be found in the aircraft structural repair manual or in drawings and specifications.

Before a thorough inspection of the damage can be made, the area should be cleaned with a cloth saturated with methyl ethyl ketone (MEK). After drying, the paint should be removed by sanding lightly with No. 280 grit sandpaper, and then clean the sanded area with MEK. The extent of damage can then be determined by tapping the suspected areas with a blunt instrument. You could use a coin as a blunt instrument, such as a quarter, to perform the tap test. This is referred to as the "coin tap" method. You should never use a hammer as a blunt instrument. The damaged areas will have a dull or dead sound, while the undamaged areas will have a clear metallic sound. Damages are divided into four general classes: surface damage, facing and core damage, puncture damage (both facings and core), and damage requiring replacement.