AMC1 to ASTM F2245-12d Sub-chapter 6.2 Materials
ED Decision 2013/015/R
Parts of Structure Critical to Safety
(a) 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:
|
Material used |
Allowable
normal stress level of maximum limit load |
|
—
Glass rovings in epoxy resin —
Carbon fibre rovings in epoxy resin —
Wood —
Aluminium Alloy —
Steel
Alloy |
25 daN/mm2 40 daN/mm2 According to ANC-18* Half of rupture tensile strength Half of rupture tensile strength |
(b) Higher stress levels need further fatigue investigation using one or a combination of the following methods:
(1) By a fatigue test, based on a realistic operating spectrum.
(2) 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).
Material Strength Properties and Design
Values (Interpretative material)
Material specifications should be those contained in documents accepted either specifically by the Agency or by having been prepared by an organisation or person that the Agency accepts has the necessary capabilities. In defining design properties these material specification values should be modified and/or extended as necessary by the constructor to take account of manufacturing practices (for example method of construction, forming, machining and subsequent heat treatment).
[Amdt LSA/1]
EASA LSA regulations outline acceptable stress levels for aircraft structural materials like glass, carbon fiber, wood, aluminum, and steel alloys to ensure safety. Higher stress requires fatigue testing or calculations. Material specifications must be agency-approved, considering manufacturing impacts on design properties for light sport aeroplanes.
* Summary by Aviation.Bot - Always consult the original document for the most accurate information.
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