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 | 7-44. Close-Tolerance Bolts
9/8/98
AC 43.13-1B
TABLE 7-1. Recommended torque values (inch-pounds).
CAUTION
THE FOLLOWING TORQUE VALUES ARE DERIVED FROM OIL FREE CADMIUM PLATED THREADS.
Thread Size
TORQUE LIMITS RECOMMENDED FOR INSTAL-
LATION (BOLTS LOADED PRIMARILY IN SHEAR)
Tension type nuts
MS20365 and AN310
(40,000 psi in bolts)
Shear type nuts MS20364
and AN320 (24,000 psi in
bolts)
FINE THREAD SERIES
MAXIMUM ALLOWABLE
TORQUE LIMITS
TIGHTENING
Nuts MS20365 and
AN310 (90,000 psi in
bolts)
Nuts MS20364 and
AN320 (54,000 psi in
bolts)
8-36
10-32
1/4-28
5/16-24
3/8-24
7/16-20
1/2-20
9/16-18
5/8-18
3/4-16
7/8-14
1-14
1-1/8-12
1-1/4-12
12-15
20-25
50-70
100-140
160-190
450-500
480-690
800-1000
1100-1300
2300-2500
2500-3000
3700-5500
5000-7000
9000-11,000
7-9
12-15
30-40
60-85
95-110
270-300
290-410
480-600
600-780
1300-1500
1500-1800
2200-3300*
3000-4200*
5400-6600*
20
40
100
225
390
840
1100
1600
2400
5000
7000
10,000
15,000
25,000
12
25
60
140
240
500
660
960
1400
3000
4200
6000
9000
15,000
COARSE THREAD SERIES
8-32
10-24
1/4-20
5/16-18
3/8-16
7/16-14
1/2-13
9/16-12
5/8-11
3/4-10
7/8-9
12-15
20-25
40-50
80-90
160-185
235-255
400-480
500-700
700-900
1150-1600
2200-3000
7-9
12-15
25-30
48-55
95-100
140-155
240-290
300-420
420-540
700-950
1300-1800
20
35
75
160
275
475
880
1100
1500
2500
4600
12
21
45
100
170
280
520
650
900
1500
2700
The above torque values may be used for all cadmium-plated steel nuts of the fine or coarse thread series which
have approximately equal number of threads and equal face bearing areas.
* Estimated corresponding values.
7-44. CLOSE-TOLERANCE BOLTS.
Close-tolerance, hex head, machine bolts
(AN173 through AN186), 100-degree counter-
sunk head, close-tolerance, high-strength bolts
(NAS333 through NAS340), hex head, close-
tolerance, short thread, titanium alloy bolts
(NAS653 through NAS658), 100-degree
countersunk flathead, close-tolerance titanium
alloy bolts (NAS663 through NAS668), and
drilled hex head close-tolerance titanium alloy
bolts (NAS673 through NAS678), are used in
applications where two parts bolted together
are subject to severe load reversals and vibra-
tion. Because of the interference fit, this type
of bolt may require light tapping with a mallet
to set the bolt shank into the bolt hole.
NOTE: Elimination of friction in in-
terference fit applications may some-
times be attained by placing the bolt
in a freezer prior to installation.
When this procedure is used, the bolt
should be allowed to warm up to am-
bient temperature before torquing.
CAUTION: Caution must be exer-
cised in the use of close-tolerance bolts
for all critical applications, such as
Par 7-43
Page 7-9