Originally published January 1997
Why doesn't Aircraft Spruce (or anyone else) stock an AN3-18A bolt? No, it's not an error or a lack of demand. And don't try calling Charleen Beam trying to special order one.
If you think you know why, see your friendly Newsletter Editor to check your answer.
Hi, I just received the January Newsletter (I know the mail is slow), and wanted to answer your hardware quiz.
The numbers of an AN bolt indicate both the diameter and the length of the bolt. The number immediately after the AN and before the "-" represents the bolt's diameter in sixteenths of an inch, (i.e. AN3 bolts are 3/16" in diameter. The number following the "-" indicates the bolt's length. The units digit providing the fractional size in eighths of an inch, and the tens digits showing the whole inch size, (i.e."-6" is 6/8 inch long, while "-16" is 1-6/8 inches long). The AN3-18A would be a bolt with a diameter of 3/16 of an inch, with a length of 1 and 8/8 inches. In other words, 2 inches long, so this bolt would be properly identified as AN3-20A. (By the way the "A" at the end indicates an undrilled shank). If you look at the listings for AN bolts you will not see any ending in a "8." They go from "-#7" to "-#0".
I hope this passed the quiz. Bye for now, I have to brave the black ice, and American drivers on English roads (bad combination).
RAF Mildenhall, UK
(Good job Dan--I couldn't have written a better answer myself!--ed)
Contents of The Leading Edge and these web pages are the viewpoints of the authors. No claim is made and no liability is assumed, expressed or implied as to the technical accuracy or safety of the material presented. The viewpoints expressed are not necessarily those of Chapter 1000 or the Experimental Aircraft Association.
Revised -- 9 September 1997