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Review of FAA Material Specification Guidelines Document. John Adelmann – August, 2002. General Comments Comments on Specific Sections. General Comments. Material specifications have 2 major functions:. Material Definition / Description
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Review ofFAA Material SpecificationGuidelines Document John Adelmann – August, 2002 • General Comments • Comments on Specific Sections FAA / NASA Workshop, Chicago, IL – August 6-8, 2002
General Comments Material specifications have 2 major functions: • Material Definition / Description • Describe material completely enough so it is clear what is to be procured • Define the requirements for qualification to the specification • Material Control • Provide requirements and procedures that assure that material procured over time does not significantly deviate from the material that was originally qualified Other information in specifications is secondary FAA / NASA Workshop, Chicago, IL – August 6-8, 2002
General Comments • MIL-HDBK-17 / SAE AMS Activity • Tentative ground rules established • AMS Spec. format adopted • FAA and MIL-17 / SAE should be consistent • DoD (Military) Applications • Standardizing FAA procedure covers only part of the aircraft / aerospace composites usage • Should have discussions with DoD to get buy-in to FAA process FAA / NASA Workshop, Chicago, IL – August 6-8, 2002
Specific Comments • Section 3 • Need to decide what goes in the base spec. and what goes on slash sheets (MIL-17 / SAE has already set preliminary guidelines for this) • Type, Form, Grade, and Class need better definition • Need to think ahead to specs. for other materials and forms and maintain some consistency • Must be careful not to include slash sheet items in the Type, Form, Grade, or Class definitions (Class defines a specific fiber in proposed FAA definitions) FAA / NASA Workshop, Chicago, IL – August 6-8, 2002
Specific Comments • Section 6 • Second paragraph in 6.1 not in agreement with scope that spec. covers multiple materials (on different slash sheets) • Table 4 – Glass transition should be “ambient” or “wet,” but should not state “RT” or “hot” since Tg is a temperature. • Section 6 should specify what, when, how, and how many to test. Numerical requirements are on slash sheets. Draft Section 6 appears to do this. FAA / NASA Workshop, Chicago, IL – August 6-8, 2002
Specific Comments • Section 7 • Section 7.1 recommends values for alpha for equivalency and batch acceptance. Alpha values are still under review within MIL-HDBK-17. • Question the need for a maximum average requirement for strength properties • Section 7.2 – Good idea to develop batch acceptance requirements with more than first 3 batches, but caution is needed if values will be revised over time (how does this affect basis values?). FAA / NASA Workshop, Chicago, IL – August 6-8, 2002
Specific Comments • Section 9 • Section 9.4.2 requires FAA approval to change supplier testing level for mature processes. Need provisions based on history of conformance that allow reduced testing without need for FAA involvement each time. FAA / NASA Workshop, Chicago, IL – August 6-8, 2002