AMC No 2 to CS 25.603(a) Suitability and durability of materials -- Large glass items

• ED Decision 2021/015/R found in: CS-25 Amdt 27 - Large Aeroplanes (Jan 2023)

AMC No 2 to CS 25.603(a) Suitability and durability of materials — Large glass items ED Decision 2021/015/R 1. General This AMC defines acceptable minimum performance standards for the specific case of large glass items used as an interior material in passenger cabin installations whereby the glass items carry no other loads than those resulting from the mass of the glass itself, rapid depressurisation, or abuse loading. Large glass items should be shown not to be a hazard during events such as an emergency landing and cabin depressurisation. 1.1. A large glass item is defined as: (a) a glass item with a dimension that exceeds 51 cm (20 in.); (b) a glass panel with a surface area on one side that exceeds 0.12 m² (200 in.²); or (c) a glass item with a mass exceeding 4 kg. In case of multiple items in close proximity, the accumulated surface area of glass as well as the total mass should be considered (i.e. effects such as tiling should be considered). 1.2. A large glass item should meet the following requirements whenever installed in compartments that may be occupied during taxiing, take-off, and landing, or may be traversed during an emergency evacuation: (a) The glass item should be subjected to, and pass, ball impact testing (see paragraph 2 below). (b) The glass item should be subjected to, and pass, abuse load testing (see paragraph 3 below). (c) The glass item should meet the requirements outlined in CS 25.561(b)(3), (c) and (d). A safety factor of 2.0 should be applied to glass items to account for variability in the production of the material and for long-term degradation. (d) Cracking of glass should not produce a condition where the material may become hazardous to the occupants (e.g. sharp edges, splinters or separated pieces). This requires destructive testing. If any of the test conditions defined below (see paragraphs 2 and 3 below) do not result in a significant failure of the glass item, testing at a higher impact energy (ball impact test) or load (abuse load test) should be performed until destruction, or until an impact energy of 80 J or double the specified abuse load is reached. Tests should be performed for worst-case conditions (e.g. the largest glass item should be tested with the maximum engraving). Similarity justification may then be used for other items. These tests do not need to be performed for glass items that have traditionally been installed in large aeroplanes, provided that their installation method, location, etc. are not unusual (e.g. standard lavatory mirrors, light bulbs, light tubes, galley equipment). The instructions for continued airworthiness should reflect the fastening method used and should ensure the reliability of all methods used (e.g. life limit of adhesives, or scheduled check for security of a clamp connection). For example, inspection methods and intervals for an adhesive-based design should be defined in accordance with adhesion data from the manufacturer of the adhesive, or actual adhesion test data, as necessary. 2. Ball Impact Tests The test procedure(s) and pass/fail criteria of the Underwriters Laboratories standard UL 61965, Mechanical safety for cathode ray tubes, Edition 2, 27 July 2004, or former UL 1418, Standard for safety cathode ray tubes, Edition 5, 31 December 1992, or other equivalent approved method are the basis of the ball impact strength and no-hole tests described in this paragraph, combined with the impact energy in Section 5.12.2 of ANSI/SAE Z26.1, Safety glazing materials for glazing motor vehicles and motor vehicle equipment operating on land highways — safety standard, 1 December 1997. The glass samples should be installed in a test fixture representative of the actual installation in the cabin. 2.1. Strength Test The large glass item should be subjected to a single impact applied in accordance with the test conditions of paragraph 2.3 below. The impact energy should be 21 J, caused by a 51-mm diameter ball or, alternatively, by a 40-mm diameter ball, as specified in paragraph 2.3.2 below. The test is passed if the expulsion of glass within a 1-min period after the initial impact satisfies the following criteria: (a) there is no glass particle (a single piece of glass having a mass greater than 0.025 g) between the 0.90 and 1.50-m barriers (see paragraph 2.3.1) on either side (if appropriate); (b) the total mass of all pieces of glass between the 0.90 and 1.50-m barriers (see paragraph 2.3.1) does not exceed 0.1 g on either side (if appropriate); and (c) there is no glass expelled beyond the 1.50-m barrier (see paragraph 2.3.1) on either side (if appropriate). 2.2 No-Hole Test The large glass item should be subjected to a single impact applied in accordance with the test conditions of paragraph 2.3 below. The impact energy should be 3.5 J, caused by a 51-mm diameter ball as specified in paragraph 2.3.2 below. The test is passed if the large glass item does not develop any opening that may allow a 3 mm diameter rod to enter. *Note: If the large glass item does not develop any opening that would allow a 3 mm rod to enter when subjected to the strength test defined in paragraph 2.1 above, the no-hole test defined in this paragraph does not need to be performed.* 2.3 Test Conditions 2.3.1 Test Apparatus and Setup The large glass item should be mounted in a way representative of the aeroplane installation. The centre of the large glass item should be 1.00 ± 0.05 m above the floor. For the strength test (see paragraph 2.1 above), two barriers, each one made of material 10–20 mm thick, 250 mm high, and 2.00 m long, should be placed on the floor in front of the test item (or on both sides in case of a glass partition) at the specified location, measured horizontally from the front surface of the large glass item to the near surface of the barrier. The barriers may be less than 2.00 m long, provided that they extend to the walls of the test room. A non-skid surface such as a blanket or rug may be placed on the floor. A solid, smooth, steel ball of the size specified in paragraph 2.3.2 below should be suspended by suitable means such as a fine wire or chain and allowed to fall freely as a pendulum and strike the large glass item with the specified impact energy. The large glass item should be placed in a way that its surface is vertical and in the same vertical plane as the suspension point of the pendulum. A single impact should be applied to any point on the surface of the large glass item at a distance of at least 25 mm from the edge of the surface. 2.3.2 Impact Objects The 51-mm diameter steel ball, used as an impact object, should have a mass of approximately 0.5 kg and a minimum Scale C Rockwell Hardness of 60. The 40-mm diameter steel ball, used as an impact object, should have a mass of approximately 0.23 kg and a minimum Scale C Rockwell Hardness of 60. 3. Abuse Loads Tests The large glass item should withstand the abuse loads defined in paragraph 3.2 below when subjected to the test conditions defined in paragraph 3.1. The panel should remain attached to the fixture, and any failure should be shown to be non-hazardous (e.g. no sharp edges, no separation of pieces). 3.1 Test conditions Abuse loads should be applied: (a) at the points that would create the most critical loading conditions; and (b) at least at the geometrical centre, and at one point located along the perimeter. For the above-mentioned load applications, it is acceptable to use any loading pad with a shape and dimensions that fit into a 15.24-cm (6-in.) diameter circle. For all tests, the glass item should be mounted in a test fixture representative of the actual installation in the cabin. 3.2 Loads to be applied Abuse loads should be considered as ultimate loads, therefore, no additional factors (e.g. fitting factors, casting factors, etc.) need to be applied for abuse load analysis/testing. Unless it is justified that one or more abuse load cases are not applicable due to the shape/size/location of the glass item making it unlikely or impossible for persons to apply loads in the direction(s) concerned, the following abuse loads should be considered (see also Figure 1 below): 3.2.1 Pushing loads Pushing loads are 133 daN (300 lbf) from 0–1.5 m (60 in.) above the floor, reducing linearly to 44 daN (100 lbf) at 2 m (80 in.) above the floor level (see (1) in Figure 1 below). 3.2.2 Pulling loads One-hand pull loads (where it is not possible to grab with two hands) are 66 daN (150 lbf) from 0–1.5 m (60 in.) above the floor, reducing linearly to 22 daN (50 lbf) at 2 m (80 in.) above the floor level (see (3) in Figure 1 below). Two-hands pull loads are 133 daN (300 lbf) from 0–1.5 m (60 in.) above the floor, reducing linearly to 44 daN (100 lbf) at 2 m (80 in.) above the floor level (see (1) in Figure 1 below). 3.2.3 Up loads Up loads are 66 daN (150 lbf) from 0–1.5 m (60 in.) above the floor, reducing linearly to 22 daN (50 lbf) at 2 m (80 in.) above the floor level (see (2) in Figure 1 below). 3.2.4 Downloads Downloads are 133 daN (300 lbf) from 0-1.5 m (60 in.) above the floor, reducing linearly to 44 daN (100 lbf) at 2 m (80 in.) above the floor level (see (1) in Figure 1 below). 3.2.5 Stepping, Seating loads In the case of large glass items which may be stepped or sat on, a load of 222 daN (500 lbf) should be used. This load is to be applied at the most critical point, and on any relevant surface up to 1 m (38 in.) above the floor level (see (4) in Figure 1 below).  Figure 1 [Amdt No: 25/19] [Amdt No: 25/27]