3.1 This guide is intended for use by material suppliers, aircraft transparent enclosure fabricators, air-frame manufacturers, government agencies, and others that may become involved in the testing of transparency components. These test methods provide data on both individual materials and material combinations commonly utilized in the fabrications of aerospace transparent enclosures comprised of monolithic plastic, coated monolithic plastic or laminated constructions containing plastics.

3.2 Primary properties and their long term stability are critical to the performance of aerospace transparent enclosures. Property measurement tests define as-manufactured material properties of these materials. Aging procedures provide for exposure of parts or representative sections to environments that may induce changes in material properties as determined in property measurement tests. Property measurement tests performed before and after aging exposure provide a means of estimating the potential usable life span of a transparency or to compare the durability of one material with another.

3.3 When employing these test methods for comparison of materials for weathering effects the user should be aware that the many factors influencing degradation due to weathering vary from one location to another. For direct weathering comparisons, all material(s) should undergo exposure conditions and property measurements testing at the same time.

3.4 The test methods listed include those considered critical to the performance of aircraft transparent enclosures. Other test methods to evaluate materials may also be performed. Additional test methods are in preparation and will be incorporated. The user is advised to employ the latest revision of any test method.

3.5 The dominant component of all transparent enclosures is one, or more, rigid transparent sheet(s). The sheet(s) must permit the necessary visibility while providing structural integrity and protecting the aircraft interior from external environments as required by the specific aircraft design.

3.6 In its most simple form, the rigid transparent sheet may be the only component of a transparent enclosure.

3.7 When more than one rigid transparent sheet is employed, the sheets are laminated with a controlled thickness with either an air gap or with a transparent adhesive known as an interlayer.

3.8 Transparent enclosure designs may use multiple rigid transparent sheets to take advantage of specific properties of different materials. In this instance, there will be functions required of one of the sheets but not the other.

3.9 The test methods, practices and guides listed are a summary of the available test methods applicable to plastic transparent enclosures. They are presented in this format to simplify the search and to enable the user to determine if a method applicable to his requirements is available.