Significance and Use
4.1 This standard practice provides one means for determining fatigue load spectra for aeroplane durability assessments. This information can be used in conjunction with Specification F3115/F3115M, Section 5, Load Considerations.
4.1.1 Users of this practice may propose alternate spectra, subject to the approval of their CAA.
4.2 The methods are applicable to the durability evaluation of wings of small aeroplanes. Additional calculation (such as methods noted in ACE-100-01) are needed to properly develop load spectra for fatigue evaluation of empennage and/or configurations with canards (or forward wings) and/or winglets (or tip fins), fuselage, and potentially other components, with approval from appropriate regulatory agency.
4.3 Much of the material presented herein is directly taken from AC 23-13A. The FAA developed the flight load spectra, presented herein, based on a statistical analysis of the data presented in DOT/FAA/CT-91/20. The ground load spectra are directly from AFS-120-73-2.
4.4 The flight load spectra, presented in Section 7, includes an adjustment (1.5 standard deviations) to the average measured load frequency. The adjustment accounts for the variability in the loading spectra experienced by individual aeroplanes, as well as across aeroplane types. The magnitude of the adjustment was selected to maintain the probability that a component will reach its safe-life without a detectable fatigue crack established by scatter factor (see paragraph 2–15 of AC 23-13A).
Scope
1.1 This practice provides data to develop simplified loading spectra that can be used to perform structural durability analysis for aeroplanes, specifically for wings of small aeroplanes. The material was developed through open consensus of international experts in general aviation. The information was created by focusing on Level 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 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this 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.
