FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 7. Aircraft Hardware, Control Cables, and Turnbuckles | 3. Bolts | 7-50. Clevis Bolts
AC 43.13-1B
landing gear, control systems, and
helicopter rotary controls. Do not
substitute for close-tolerance fasteners
without specific instructions from the
aircraft manufacturer or the FAA.
9/8/98
MS9039), and drilled twelve point head ma-
chine bolts (MS9088 through MS9094), are
similar to the (NAS624 through NAS644); but
are made from different steel alloys, and their
shanks have larger tolerances.
7-45. INTERNAL WRENCHING BOLTS
(NAS144 THROUGH NAS158 AND NAS172
THROUGH NAS176). These are high-
strength bolts used primarily in tension appli-
cations. Use a special heat-treated washer
(NAS143C) under the head to prevent the
large radius of the shank from contacting only
the sharp edge of the hole. Use a special heat-
treated washer (NAS143) under the nut.
7-46. INTERNAL WRENCHING BOLTS
(MS20004 THROUGH MS20024) AND SIX
HOLE, DRILLED SOCKET HEAD BOLTS
(AN148551 THROUGH AN149350). These
are very similar to the bolts in paragraph 7-45,
except these bolts are made from different al-
loys. The NAS144 through NAS158 and
NAS172 through NAS176 are interchangeable
with MS20004 through MS20024 in the same
thread configuration and grip lengths. The
AN148551 through AN149350 have been su-
perseded by MS9088 through MS9094 with
the exception of AN149251 through 149350,
which has no superseding MS standard.
7-47. TWELVE POINT, EXTERNAL
WRENCHING BOLTS, (NAS624
THROUGH NAS644). These bolts are used
primarily in high-tensile, high-fatigue strength
applications. The twelve point head, heat-
resistant machine bolts (MS9033 through
7-48. CLOSE-TOLERANCE SHEAR
BOLTS (NAS464). These bolts are designed
for use where stresses normally are in shear
only. These bolts have a shorter thread than
bolts designed for torquing.
7-49. NAS6200 SERIES BOLTS. These
are close tolerance bolts and are available in
two oversized diameters to fit slightly elon-
gated holes. These bolts can be ordered with
an “X” or “Y” after the length, to designate the
oversized grip portion of the bolt (i.e.,
NAS6204-6X for a 1/4 inch bolt with a
1/64 inch larger diameter). The elongated hole
may have to be reamed to insure a good fit.
7-50. CLEVIS
BOLTS
(AN21
THROUGH AN36). These bolts are only
used in applications subject to shear stress, and
are often used as mechanical pins in control
systems.
7-51. EYEBOLTS (AN42 THROUGH
AN49). These bolts are used in applications
where external tension loads are to be applied.
The head of this bolt is specially designed for
the attachment of a turnbuckle, a clevis, or a
cable shackle. The threaded shank may or may
not be drilled for safetying.
7-52.7-62. [RESERVED.]
Page 7-10
Par 7-44