MIL-DTL-18240F
e. Identification of product.
4.4.2 Torque test. For qualification testing 10 sample fasteners with self-locking elements
installed as specified in table IV shall be tested with the test nuts specified in tables VA and VB.
For quality conformance purposes, the bolts shall be as specified in the applicable document which
requires a self-locking element per MIL-DTL-18240 and the test nut shall be as specified in table
VA and VB for the correct thread type. The following test shall be performed:
NOTE: Parts that can not be seated shall be tested unseated.
a. Prior to the actual testing of self-locking screws and bolts, a test nut as
specified in table VA and table VB with the same thread form, class and pitch,
shall be gauged with a go and no go threaded plug gage. The test nut shall not
accept the no go gage for more than 1.5 turns and shall freely accept the go gage
for the entire length of the nut. The minor thread diameter shall also be checked
for conformance with table VA and VB.
b. A light lubricating oil shall be applied directly to the locking element prior to
torque testing, unless otherwise specified. ( see 6.4.1)
c. The torque shall be measured using a calibrated torque wrench in accordance
with GGG-W-686 or a digital torque sensor capable of measuring the torque
values encountered during the test. (see 6.4.2)
d. A self-locking fastener shall be assembled with hardened spacers, or washers as
necessary, and a test nut. The total thickness of the spacers and washers for the
test assembly shall be selected so that the locking element of the self-locking
fastener is fully engaged in the test nut. Set screws shall be tested in a blind hole.
If the self-locking fastener is turned, the restraining mechanism shall be such that it
imparts no radial load to the nut. For testing of self-locking fastener without
sufficient thread length for a locking element in accordance with table I or for
thread sizes not covered in table II only a positive indication of off prevailing
torque is required for five cycles. Sufficient thread length is eight threads (one
complete thread pitch, plus five complete thread pitches for the locking element,
plus two run-out pitches for ease of starting, for a total of eight threads minimum.)
Sufficient thread length may be calculated as follows:
7
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business