ASTM_F_3115_-_F_3115M_-_15.pdf

Designation:F3115/F3115M15Standard Specification forStructural Durability for Small Airplanes1This standard is issued under the fixed designation F3115/F3115M;the number immediately following the designation indicates the yearof original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This specification addresses the airworthiness require-ments related to structural durability for the design of smallairplanes.1.2 This specification was originally conceived for smallairplanes as defined in the F44 terminology standard but mayfind broader applicability.Use of the term aircraft throughoutthis specification is intended to allow the relevant CAA(s)toaccept this standard as a means of compliance as theydetermine it to be appropriate,whether for small airplanes orfor other types of aircraft.1.3 The applicant for a design approval must seek individualguidance from their respective CAA body concerning the useof this standard as part of a certification plan.For informationon which CAA regulatory bodies have accepted this standard(in whole or in part)as a means of compliance to their SmallAirplane Airworthiness Rules(hereinafter referred to as“theRules”),refer to ASTM F44 webpage(www.ASTM.org/COMMITTEE/F44.htm)which includes CAA website links.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalues from the two systems may result in non-conformancewith the standard.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2F3060 Terminology for Aircraft2.2 Federal Aviation Regulations:314 CFR Part 23 Amendment 62,23.571 through 23.575,23.6272.3 EASA Requirements:CS 23,23.571 through 23.575CS-VLA3.Terminology3.1 The following are a selection of relevant terms.SeeTerminology F3060 for more definitions and abbreviations.3.2 Definitions:3.2.1 fatiguethe process of progressive localized perma-nent structural change occurring in a material subjected toconditions that produce fluctuating stresses and strains at somepoint or points,which may result in cracks or complete fractureafter a sufficient number of fluctuations.3.2.2 safe lifethe safe-life of a structure is that number ofevents,such as flights,landings,or flight hours,during whichthere is a low probability that the strength will degrade belowits design ultimate value due to fatigue cracking.3.2.3 S-N or-NStress-Life(S-N)or Strain-Life(-N)curves depict the magnitude of applied stress(S)or strain()necessary to develop a fatigue crack in a specimen at a givenlife(N),where N is expressed in the number of cyclicapplications of stress or strain.3.2.4 scatter factorthe scatter factor,or life reductionfactor,is a statistically derived divisor applied to fatigue testresults to account for the variation in fatigue performance ofbuilt-up or monolithic structures and usage variability.Ascatter factor can also be used in a fatigue analysis to addressthe uncertainties inherent in a fatigue analysis.3.2.5 fail safefail-safe is the attribute of the structure thatpermits it to retain its required residual strength for a period ofunrepaired use after the failure or partial failure of a principalstructural element.3.2.6 damage tolerancedamage tolerance is the attributeof the structure that permits it to retain its required residual1This specification is under the jurisdiction ofASTM Committee F44 on GeneralAviation Aircraft and is the direct responsibility of Subcommittee F44.30 onStructures.Current edition approved June 1,2015.Published September 2015.DOI:10.1520/F3115_F3115M-15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from U.S.Government Printing Office Superintendent of Documents,732 N.Capitol St.,NW,Mail Stop:SDE,Washington,DC 20401,http:/www.access.gpo.gov.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 strength for a period of use after the structure has sustained agiven level of fatigue,corrosion,accidental,or discrete sourcedamage.3.2.7 residual strengththe strength capability of a struc-ture after the structure has been damaged due to fatigue,corrosion,or discrete source damage.The residual strengthcapability includes consideration of static strength,fracture,and stiffness.4.Metallic Structure4.1 The s