AN175 Close Tolerance Airframe Bolt, 5/16-24 Thread

AN175 bolts are a special close-tolerance version of the more common AN5 aircraft bolt. The nominal 5/16" shank diameter is precision-ground to be within a range of 0.0005" -- a diameter tolerance 6 times tighter than a standard AN5 bolt.

To realize the full benefit of these bolts, the hole must be drilled undersized (19/64" or N size drill) and finished with a reamer. An accurate 5/16" (0.3125") reamed hole will provide 0.0008" to 0.0013" clearance. If necessary for the application, a light press-fit can be achieved by using an undersized reamer.

AN175 bolts have 5/16-24 UNF-3A threads and a 5/16" diameter shank. All sizes of AN175 bolts have a 0.532 inch thread length (+.047 / -.032), regardless of grip length. This thread length has been designed specifically to accommodate a full-height nut and one AN960-516 washer. Sold individually; nuts and washers sold separately.

Grip Length refers to the length of the unthreaded portion of the shank. Grip lengths are available in 1/8" increments to match the thickness of the materials being bolted together (the threaded portion should never be positioned inside the hole). If your assembly is between sizes, select the next longer bolt and use additional AN960-516 and/or AN960-516L washers to take up the slack.

A or no A? AN bolts were originally designed to be used with a castle nut and cotter pin, so the base part number indicates a drilled shank. The addition of an "A" at the end (for example, AN175-13A) indicates an undrilled shank for use with a self-locking nut.

UHL: Under Head Length (also known as Full Shank Length or Overall Length not including bolt head)

AN bolt nomenclature can be confusing. Please take a look at our page on Identifying AN Bolt Sizes.