1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2009 SAE International All rights reserved. No part of this publication m
3、ay be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA)
4、 Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AIR5689A AEROSPACE INFORMATION REPORT AIR5689A Issued 2000-03 Revised 2009-11 Superseding AIR568
5、9 Light Transmitting Glass Covers for Exterior Aircraft Lighting RATIONALE The AIR has been revised to further clarify glass quality definitions and add dimesions to glass defects that are commonly present in glass lenses 1. SCOPE This SAE Aerospace Information Report (AIR) provides definitions of a
6、nd inspection criteria for defects commonly encountered in molded and finished glass covers for exterior aircraft lighting. 1.1 Purpose This document covers, but is not limited to, visual inspection and evaluation recommendations for molded glass covers used in exterior aircraft lighting application
7、s. The included definitions are for those defects most commonly encountered. The goal is to provide specific evaluation criteria in the following areas. a. Color b. Internal Quality c. External (Surface) Quality d. Dimension e. Coatings Inspection of glass covers shall be made at a typical reading d
8、istance with normal or corrected 20-20 vision under adequate lighting. Covers shall be free from defects which will prevent meeting intensity and beam distribution, strength, thermal shock, and other physical requirements. All covers shall be manufactured and finished using quality workmanship. 2. A
9、PPLICABLE DOCUMENTS The following publications form a part of this document to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other publications shall be the issue in effect on the date of the purchase order. In the event of conflict between th
10、e text of this document and references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. .Copyright SAE International Provided by IHS under license with SAENot for Res
11、aleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR5689A Page 2 of 5 2.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. AS25050 Col
12、ors, Aeronautical Lights and Lighting Equipment, General Requirements For 2.2 U.S. Government Publications Available from the Document Automation and Production Service (DAPS), Building 4/D, 700 Robbins Avenue, Philadelphia, PA 19111-5094, Tel: 215-697-6257, http:/assist.daps.dla.mil/quicksearch/. M
13、IL-DTL-7989B Covers, Light-Transmitting For Aeronautical Lights, General Specification For (INACTIVE FOR NEW DESIGN) MIL-G-174B Glass, Optical 3. RECOMMENDATIONS 3.1 Color 3.1.1 The color shall meet the specifications defined in the detailed item drawing. The drawing shall indicate the desired chrom
14、aticity in CIE 1931 coordinates, the applicable source, and the operating temperature of the lens. In the event that no color specifications are indicated, the item shall be produced to meet the requirement of specification AS25050 using a standard CIE Illuminant A (2856 K) source with a room temper
15、ature lens. 3.1.2 The color shall be homogeneous throughout the glassware. 3.1.3 Glass has the characteristic where the color will change with increased operating temperature. This effect is most apparent with sharp-cut yellow and red filter glass, but is also present to some degree in all colored g
16、lassware. The operating temperature of the lens shall be specified on the detailed drawing for all applications where chromaticity and photometric output are critical. 3.1.4 Clear uncoated glassware shall have no visible color when viewed through the optically effective surface 3.2 Internal Quality
17、3.2.1 A “check“ is a crack or fracture usually starting from an edge. A “crizzle“ is a series of fine checks occurring in one area near the surface. Cracks, checks, and crizzles are actual fractures in the glass and shall not be accepted. 3.2.2 An “inclusion“, or “stone“, is an opaque, non-glassy ma
18、terial within the bulk of the glass. A fractured inclusion has small cracks surrounding the area of the stone and leading into the glass. Fractured stones shall not be accepted. The maximum acceptable inclusion size is related to the overall dimension of the item and the magnitude of thermally induc
19、ed stress in the lens during operation. 3.2.3 “Knots“ are transparent areas of incompletely melted glass. The inspection criteria for knots are the same as those for inclusions in 3.2.2. 3.2.4 “Striae“, or “cords“, are apparent as lines or threads within the lens, and are caused by slight variations
20、 of the refractive index in the bulk of the glass. Cords not visible to the unaided eye and not detrimental to the output of a lens shall not be cause for rejection. Striae which are light and scattered when viewed perpendicular to the optically effective surface are acceptable so long as the output
21、 of the lens is not affected. Heavy cords which appear on the surface of the lens or degrade the physical integrity or photometric output of the lens are unacceptable. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without lice
22、nse from IHS-,-,-SAE AIR5689A Page 3 of 5 3.2.5 “Bubbles“ are pockets of gas trapped within the bulk of the glass. The specifications for bubble criteria are adapted from MIL-C-7989B (INACTIVE FOR NEW DESIGN). 3.2.5.1 Bubbles should not be so large in size or number that they affect the transmittanc
23、e of the part. The percentage of useful surface area of the lens obstructed by bubbles should not exceed one. The total number of bubbles shall not exceed the number shown in Table 1. TABLE 1 Effective Diameter of Bubbles in Inches Number of Bubbles per Effective Square Inch of Projected Area of Cov
24、er 0.050-0.060 3 0.040-0.050 4 0.030-0.040 6 0.020-0.030 11 0.015-0.020 25 0.010-0.015 44 0.005-0.010 100 3.2.5.2 Diffusing covers shall not be required to meet any bubble requirements. 3.2.5.3 “Blisters“ are bubbles which exceed 0.060 in. in diameter. The size and thickness of an item shall be cons
25、idered when determining the maximum allowable size of a blister. 3.3 External Quality 3.3.1 Elongated blisters which catch a fingernail on the lens shall not be accepted. Open surface blisters or blisters which can be punched open with a fingernail or pencil point shall be rejected. 3.3.1.1 Elongate
26、d seeds which catch a fingernail on the lens are acceptable providing they are less than 0.015 in. deep. 3.3.2 “Wrinkles“, or “chill marks“, are slight wavy areas on the surface of the lens caused by variations in mold temperature and glass cooling. Unless the surface deformation is great enough to
27、affect the output of the lens, wrinkles are cosmetic defects and shall be acceptable. 3.3.3 “Shear“ marks are caused by the slicing and cooling action of the shears used in cutting an individual gob of glass for manufacturing the part. Typically the glass gob is hot enough to smooth any roughness wh
28、ich may have been caused by the shearing action. After molding the shear mark should appear as a smooth, possibly irregularly shaped line on the surface. The glass within the shear mark should be well fused and not act as a concentration point for residual stress. Rough shear marks, characterized by
29、 a raised mark or abraded edges, shall be rejected. Although generally cosmetic defects, shear marks should be in locations which have minimal impact on the light output of the lens. 3.3.4 Chips and Flakes 3.3.4.1 “Flakes“ are small voids along an abraded or sliced edge. There shall be no cracked or
30、 residual glass remaining in the region of the flake. Flakes shall be acceptable so long as no cracks emanate from the flake into the bulk of the part. 3.3.4.2 “Chips“ are larger voids along a sharp edge which are caused by contact of the glass with a hard surface under sufficient force to break off
31、 a piece of the glass. There shall be no cracked or residual glass remaining in the region of the chip. Chips are acceptable if no crack protrudes from the site of the chip into the bulk of the glass. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or
32、networking permitted without license from IHS-,-,-SAE AIR5689A Page 4 of 5 3.3.4.3 The acceptable size of chips and flakes depends on the dimension of the part. Chips or flakes shall not be larger than 1/4 of the width of the bottom mounting flange of the part. Chips and flakes should not extend int
33、o the main body of the lens on either the inside or the outside. Chips and flakes should not extend for more than 0.060 in for lenses less than or equal to 4 in maximum dimension, or more than 0.125 in for lenses of greater than 4 in maximum dimension. 3.3.5 “Scratches“ are rough grooves on the glas
34、s surface caused by abrasive materials or contact with sharp metal or ceramic objects. Scratches can usually be seen in reflected or off-axis lighting or can be felt by rubbing a fingernail over the surface of the glass. Coarse or deep scratches will affect the physical integrity of the lens and are
35、 unacceptable. The combined length of a light scratch should not exceed 25% of the largest dimension of the lens. 3.3.6 “Laps“, or “folds“, are smooth ridges on the glass surface. Laps are caused by two regions of glass meeting at an interface but not being sufficiently hot enough to blend together.
36、 Laps are acceptable so long as they are cosmetically acceptable and do not affect the output of the lens. 3.3.7 “Scale“ is iron oxide appearing as a reddish brown discoloration on the surface of the glass. It can usually be removed by buffing without causing permanent damage to the glass surface. 3
37、.3.8 A “scuff“ is an abrasion of the glass surface creating a cloudy or hazy appearance. Scuffs are acceptable so long as they do not affect the output of the lens. 3.3.9 “Pits“ are small surface holes caused by bits of glass or dirt on the mold surface during forming. Pits are acceptable unless the
38、y are numerous, are unsightly, affect the light output, or are in regions of known high thermal stress. 3.3.10 Sharp edges remaining from molding or finishing operations can be sources of mechanical strength problems due to thermal shock or thermal stress. All sharp edges should be removed. 3.4 Dime
39、nsions 3.4.1 All lenses should meet the dimensions and contour specified in the detailed drawing. 3.5 Coating 3.5.1 Conductive Coatings 3.5.1.1 The intent of conductive coatings is to limit the amount of electromagnetic energy into or out of a light source. An undesired effect of the coating is to r
40、educe the amount of light transmitted through the lens. The coating should not decrease the output of the uncoated lens below desired photometric levels. 3.5.1.2 “Back coating“ occurs when a coating is deposited on the side opposite to that which is being coated. This effect generally results in a c
41、loudy or hazy film on the opposite surface. Back coating is not acceptable in cases where the output of the lens is decreased below acceptable intensity levels. 3.5.1.3 “Spatter“ is a surface mark caused by the deposit of large particles of coating material on the surface of the lens. Spatter marks
42、are unacceptable if they significantly reduce the light output of a lens or degrade the required conductive performance of the coating. 3.5.1.4 A “stain“ is the discoloration of the glass surface due to a reaction between the glass and the chemicals involved in the coating process. Stains are accept
43、able when no degradation in lens performance is determined. 3.5.1.5 “Voids“ are areas where no coating has been applied and are unacceptable. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR56
44、89A Page 5 of 5 3.5.2 Opaque Coatings 3.5.2.1 An opaque coating is generally a ceramic or enamel fired-on coating. The coating should be fully cured such that there is no powdery residue on the surface and the coating cannot easily be scratched off. 3.5.2.2 “Pin holes“ are small voids in the opaque
45、coating. Pin holes larger than 0.030 in in diameter are unacceptable. There shall be no more than 2 pin holes per square inch of surface. 4. NOTES 4.1 A change bar ( l ) located in the left margin is for the convenience of the user in locating areas where technical revisions, not editorial changes,
46、have been made to the previous issue of this document. An (R) symbol to the left of the document title indicates a complete revision of the document, including technical revisions. Change bars and (R) are not used in original publications, nor in documents that contain editorial changes only. PREPARED BY SAE SUBCOMMITTEE A-20B, EXTERIOR OF COMMITTEE A-20, AIRCRAFT LIGHTING Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
