Technical data

13773-001
20-70
Page 8 30 Nov 2000
Note: Observe torque values and the installation of the recommended safetying device for
every fastener. The end of a flat end bolt or screw shall extend through the nut or nut-
plate at least 1/32”, or the end of a round or chamfered end bolt or screw shall extend
through the nut or nutplate the full round or chamfer. Do not use MS17826 nuts for ten-
sion applications. The aforementioned nuts can be used on standard and high strength
bolts.
(1) Restrictions of self-locking nuts
(a) Do not use reworked or reprocessed self-locking nuts for any application.
(b) Do not use at joints in a control system for singular attachment points.
(c) Do not use on externally threaded parts that serve as an axle of rotation for another part
where tensional (torque) loads can cause nut to loosen and/or become separated. Exam-
ples are pulleys, levers linkages, and cam followers.
Note: Self-locking nuts can be used when threaded parts are held by a positive
locking device that requires shearing or rupture before torsional loads can
act on threaded parts.
(d) Do not use where a loose nut, bolt, or screw, could fall or be drawn into an area that would
impede or damage or otherwise distort operation.
(e) Do not use for access panels, doors or to assemble components that are routinely disas-
sembled or removed for access and servicing.
(f) Do not use a self-locking nut where the loss of a bolt will affect the safety of flight.
(g) Bolts, studs, or screws, excluding Hi-Locks, must extend 1/32-inch through self-locking
nuts, for a length equivalent of approximately two threaded pitches. This length includes
chamfer.
(h) Self-locking nuts which are attached to the structure shall be attached in a positive man-
ner to eliminate possibility of their rotation or misalignment when tightening is to be
accomplished by rotating bolts to structure, and permit replacement of nuts.
Minimum Prevailing Drag Torque for Reused Self-locking Nuts
Fine Thread Course Thread
7/16 - 20
8 inch-pounds
7/16 - 14
8 inch-pounds
1/2 - 20
10 inch-pounds
1/2 - 13
10 inch-pounds
9/16 - 18
13 inch-pounds
9/16 - 12
14 inch-pounds
5/8 - 18
18 inch-pounds
5/8 - 11
20 inch-pounds
3/4 - 16
27 inch-pounds
3/4 - 10
27 inch-pounds
7/8 - 14
40 inch-pounds
7/8 - 9
40 inch-pounds
1 - 14
55 inch-pounds
1 - 8
51 inch-pounds
1 - 1/8 -12
73 inch-pounds
1 - 1/8 -8
68 inch-pounds
1 - 1/4 -12
94 inch-pounds
1 - 1/4 -8
88 inch-pounds