1.1 本规程为确定分散因素提供了指导，以确定安全寿命或检查阈值，以及将在维护手册的适航限制部分公布的检查间隔，从而保持持续的适航性。本文提供的基于循环试验、损伤容限试验、疲劳分析或损伤容限分析或其组合的合规性方法的指导材料。该材料是通过通用航空领域国际专家的公开共识开发的。该信息是通过关注1、2、3和4级普通类飞机创建的。内容可能更广泛地适用；申请人有责任证明更广泛的适用性作为一种具体的遵守手段。 1.2 打算将这些信息作为设计批准的合规手段的申请人必须就其可接受的使用和应用向其各自的监督机构寻求指导（例如，相关民航局或CAA发布的指导）。 有关哪些监督机构已接受本标准（全部或部分）作为符合其监管要求的可接受手段（以下简称“规则”）的信息，请参阅ASTM委员会F44网页（www.ASTM.org/Committee/F44.htm）。 1.3 单位-- 本文件可能以国际单位制、英语工程单位或两者兼有的形式提供信息；在每个系统中所述的值可能不是精确等效的。每个系统应独立使用；将两个系统的值结合起来可能会导致不符合标准。 1.4 本标准并不旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.5 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ====意义和用途====== 4.1 该实践提供了一种确定散射因子的方法，以确定飞机耐久性和损伤容限评估的安全寿命、检查阈值、重复检查间隔或其组合。此信息可与规范一起使用 F3115米/F3115米 . 4.1.1 本规程定义了分散系数或用于未系数试验或分析平均寿命或两者的系数，以确定系数寿命（即安全- 寿命、检查阈值或重复检查间隔，或其组合）。这些因素可能与其他因素有关，但不同于其他因素，如用于补偿长测试持续时间的负载增强因子和寿命因子。有关寿命和载荷增强系数的指导，请参阅DOT/FAA/AR-10/6或相关CAA。 4.1.2 非系数试验或分析平均寿命，或两者，必须在使用本标准实施规程之前确定（参见 4.5.1 ). 4.2 本文提供的材料来源于第节中列出的参考文献 2. . 4.3 可以为整个飞机确定安全寿命或检查阈值，也可以单独确定机翼、尾翼、起落架、控制面等部件的安全寿命或检测阈值。这些确定基于测试、与先前测试的相似性或测试支持的分析。 重复检查间隔通常在相同的基础上确定，但也可能得到在役数据的支持。 4.4 本规程中描述的分散系数适用于符合以下标准的循环试验数据: 4.4.1 循环试验品必须具有生产品的代表性。必须仔细考虑在金属结构测试之前或测试期间对试样进行的任何修改或更改，或两者兼而有之。 4.4.2 在完成全尺寸或部件疲劳/循环试验（不包括起落架）时，在确定安全寿命或检查阈值之前，必须证明残余强度能力。 4.5 以下不在本标准的范围内: 4.5.1 耐久性、损伤容限分析或试验方法，或其组合。 4.5.2 使用新型制造方法的结构，如搅拌摩擦焊接、增材制造和热塑性焊接。 4.5.3 结构连接（已证实的金属对金属连接等除外）；有关结构粘合的指导，请参阅AC 20-107B（或AMC 20-29）。 4.6 用于分析的有限元模型（FEM）必须根据相关CAA要求使用测试数据或其他独立分析方法进行验证。 4.7 使用本规程确定的检查间隔独立于其他过程定义的其他检查间隔，如维护指导小组（MSG）。

1.1 This practice provides guidance to determine scatter factors to establish either the safe-life, or inspection threshold, and inspection intervals to be published in the Airworthiness Limitation section of the maintenance manual in order to maintain continued airworthiness. The guidance materials presented herein for a means of compliance based on cyclic testing, damage tolerance testing, fatigue analysis, or damage tolerance analysis, or combinations thereof. The material was developed through open consensus of international experts in general aviation. The information was created by focusing on Levels 1, 2, 3 and 4 Normal Category aeroplanes. The content may be more broadly applicable; it is the responsibility of the applicant to substantiate broader applicability as a specific means of compliance. 1.2 An applicant intending to propose this information as Means of Compliance for a design approval must seek guidance from their respective oversight authority (for example, published guidance from applicable civil aviation authorities, or CAAs) concerning the acceptable use and application thereof. For information on which oversight authorities have accepted this standard (whole or in part) as an acceptable Means of Compliance to their regulatory requirements (hereinafter “the Rules”), refer to the ASTM Committee F44 web page (www.astm.org/COMMITTEE/F44.htm). 1.3 Units— This document may present information in either SI units, English Engineering units, or both; the values stated in each system may not be exact equivalents. Each system shall be used independently of the other; combining values from the two systems may result in nonconformance with the standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 4.1 This practice provides one means for determining the scatter factors to establish either the safe-life, or inspection threshold, or recurring inspection intervals, or combinations thereof, as a result of aeroplane durability and damage tolerance assessments. This information can be used in conjunction with Specification F3115/F3115M . 4.1.1 This practice defines scatter factors or factors to be used on the unfactored test or analytical mean lives, or both, for determining factored lives (that is, safe-life, inspection threshold, or recurring inspection intervals, or combinations thereof). These factors may be related to but are different from other factors such as load enhancement factor, and life factor that are used to compensate for long test duration. For guidance on life and load enhancement factors, refer to DOT/FAA/AR-10/6 or from relevant CAAs. 4.1.2 The unfactored test or analytical mean life, or both, must be determined prior to the usage of this standard practice (see 4.5.1 ). 4.2 The material presented herein is derived from the references listed in Section 2 . 4.3 Either the safe-life or inspection thresholds can be determined for the entire aeroplane or separately for components such as wing, empennage, landing gear, control surfaces, etc. Such determinations are based on test(s), similarity to previous test(s), or analysis supported by tests. Recurring inspection intervals are typically determined on the same basis but may also be supported by in-service data. 4.4 The scatter factors described in this practice are applicable to cyclic test data that meets the following criteria: 4.4.1 The cyclic test article must be representative of the production article. Careful consideration must be given for any modifications or alterations, or both, made to the test article prior to or during testing, or both, for metallic structures. 4.4.2 At the completion of full-scale or component fatigue/cyclic tests (excluding landing gear), the residual strength capability must be demonstrated before determining either the safe-life, or inspection threshold. 4.5 The following are not within the scope of this standard: 4.5.1 Methodologies of durability, damage tolerance analysis, or test, or combinations thereof. 4.5.2 Structures which use novel fabrication methods such as friction stir welding, additive manufacturing, and thermoplastic welding. 4.5.3 Structural bonding (except already proven metal-to-metal bonding, etc.); for guidance on structural bonding refer to AC 20-107B (or AMC 20-29). 4.6 The Finite Element Model (FEM) used for analysis must be validated with test data, or other independent analysis methods in accordance with relevant CAA requirements. 4.7 The inspection intervals determined using this practice are independent of other inspection intervals that are defined by other process, such as Maintenance Steering Group (MSG).