AIA/NAS 9800-2008 pdf download HEAD PROTRUSION GAGING, 100° FLUSH HEAD FASTENERS, GAGE BLOCK, GAGE DIAMETERS AND STYLUS
1 . SCOPE
1 .1 This specification defines the inspection criteria and requirements in inches for gaging the head protrusion values for 1 00º flush head threaded fasteners;
Type A – Rivets (i.e. NAS525).
Type B – Externally threaded 1 00º Full Flush Head fasteners (i.e. NAS1 580).
Type C – Externally threaded 1 00º Reduced Flush Head fasteners (i.e. NAS1 581 ).
1 .2 This specification includes the individual flush head protrusion gage block diameters, the method for determining applicable individual gage block diameters and acceptable gage diameter wear factors.
1 .3 Recommendations for improvement and/or corrections to this standard practice document should be directed to an NASC Representative or to the National Aerospace Standards Committee.
1 .4 Specifications herein, of issue in effect on date of price inquiry, are a part of this specification to the extent indicated. In the case of conflict, the requirements herein shall take precedence.
1 .5 This Standard Practice takes precedence over documents referenced herein.
2. REFERENCED DOCUMENTS
2.1 ASME International
ASME B46.1 – Surface Texture (Surface Roughness, Waviness, and Lay)
ASME Y1 4.5M-1 994 – Dimensioning and Tolerancing.
ASME Y1 4.36M-1 996 – Surface Texture Symbols
2.2 American Society for Testing & Material Specifications
ASTM E 1 40 – Standard Hardness Conversion Table for Metals
2.3 Aerospace Industries Association
NAS525 – Rivet, 1 00 Degree Countersunk Head
NAS1 580 – Bolt, 1 00 Degree Flush Head, 95 KSI Fsu
NAS1 581 – Bolt, 1 00 Degree Reduced Flush Head, 95 KSI Fsu
2.4 SAE International
ARP901 3 – Statistical Product Acceptance Requirements
3. DEFINITIONS
4. GENERAL REQUIREMENTS
4.1 HEAD PROTRUSION
4.2 Fastener head protrusion characteristic “H”, measured in accordance with FIGURE 1 , shall meet the requirements tabulated in TABLE I. The fastener protrusion values tabulated in TABLE I may be corrected to allow for acceptable gage block “A” diameter wear in accordance with Section 5.
The fastener head protrusion “H” shall be measured with an indicating gage calibrated to .0005 inch, fitted with astylus and mounted in a fixture to assure proper alignment. The indicating base of the fixture shall be capable ofmaintaining perpendicularity between the stylus axis (Datum A) and the fixture base.
The head angle, head cocking, and the head to shank fillet radi shall be checked by means of an opticalcomparator or by equivalent methods.
Flush head protrusion values defined in the part standard or the procurement specification shall take precedenceover the values listed herein.
The inspection sampling plan for head protrusion shall be in accordance with ARP9013, 98% IRR or higher, orTABLE IV. No rejectable conditions permitted within sample. lf one rejectable condition is found, the entire lotshall be rejected.

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