Does A320 require bolts or cap screws to have heavy hex heads?
Your page says A320 requires bolts or cap screws to have heavy hex heads. I have the 2003 edition of A320 and can’t find that requirement. Where is that requirement stated?
The ASTM A320 specification does not specifically address the physical dimensions of headed bolts. However, it does refer you to ASTM A962 for some of the physical characteristics of fasteners manufactured to the A320 specification. These specifications read as follows:
4.1 Bolting supplied to this specification shall conform to the requirements of Specification A962/A962M. These requirements include test methods, finish, thread dimensions, macroetch (carbon and alloy steels only) marking, certification, optional supplementary requirements, and others. Failure to comply with the requirements of Specification A962/A962M constitutes nonconformance with this specification.
Where “others” would refer to head dimensions.
ASTM A962/A96aM – 03
12.3.1 Hex Bolts – Unless otherwise specified in the purchase order heads shall be in accordance with the dimensions of ANSI B18.2.1 or B188.8.131.52M and the Heavy Hex screw series, should be used, except the maximum body diameter and radius of fillets may be the same as for the heavy hex bolts series.