AMC VLA 572(b) Parts of structure critical to safety (Interpretative Material and Acceptable Means of Compliance)

• ED Decision 2003/18/RM found in: CS-VLA Amdt 1 - Very Light Aeroplanes (Mar 2009)

AMC VLA 572(b) Parts of structure critical to safety (Interpretative Material and Acceptable Means of Compliance) ED Decision 2003/18/RM 1 The use of the following stress levels may be taken as sufficient evidence, in conjunction with good design practices to eliminate stress concentrations, that structural items have adequate safe lives: <table border="0" cellpadding="0" cellspacing="0" width="568"><tr><td valign="top" width="238"><p>Material used </p></td><td valign="top" width="331"><p>Allowable normal stress level of maximum limit load </p></td></tr><tr><td valign="top" width="238"><p>– Glass rovings in epoxy resin </p></td><td valign="top" width="331"><p>25 daN/mm²</p></td></tr><tr><td valign="top" width="238"><p>– Carbon fibre rovings in epoxy resin </p></td><td valign="top" width="331"><p>40 daN/mm²</p></td></tr><tr><td valign="top" width="238"><p>– Wood </p></td><td valign="top" width="331"><p>According to ANC-18* </p></td></tr><tr><td valign="top" width="238"><p>– Aluminium Alloy </p></td><td valign="top" width="331"><p>Half of rupture tensile strength </p></td></tr><tr><td valign="top" width="238"><p>– Steel Alloy </p></td><td valign="top" width="331"><p>Half of rupture tensile strength </p></td></tr></table> 2 Higher stress levels need further fatigue investigation using one or a combination of the following methods: a. By a fatigue test, based on a realistic operating spectrum. b. By a fatigue calculation using strength values which have been proved to be sufficient by fatigue tests of specimens or components. \*ANC-18 is the ANC Bulletin 'Design of wood aircraft structures'; issued June 1944 by the Army-Navy-Civil Committee on Aircraft Design Criteria (USA).