MIL-DTL-18240F
2.3 Order of precedence. In the event of a conflict between the text of this document and
the references cited herein (except for related associated specifications or specification sheets), the
text of this document shall take precedence. Nothing in this document, however, supersedes
applicable laws and regulations unless a specific exemption has been obtained.
3. REQUIREMENTS
3.1 Qualification. The self-locking elements furnished under this specification shall be
products which are authorized by the qualifying activity for listing on the applicable qualified
products list (QPL) before contract award (see 4.2 and 6.3).
3.1.1 Extent of qualification. Qualification approval of external self-locking element in UNF
or UNJC external thread constitutes approval of external self-locking element in UNC, UNJC,
UNF, UNJF, UNRC, or UNRF external thread of the same diameter.
3.2 Design. The self-locking element design shall conform to the types illustrated on
figure 1 and MS15981.
3.2.1 Dimensions. The self-locking element dimensions shall be as specified in table I,
table IA, and figure 1. In cases of dimensional conflict, the dimensions of table I, table IA and
figure 1 shall take precedence over those identified in MS15981.
3.3 Performance characteristics.
3.3.1 Torque. The self-locking fastener shall conform to the torque test as specified in 4.4.2.
3.3.2 High temperature torque. The self-locking fastener shall conform to the high
temperature torque test in 4.4.3.
3.3.3 Off prevailing torque at maximum temperature. The self-locking fastener shall meet
the off minimum prevailing torque values specified in table II at maximum temperature when
tested in accordance with 4.4.4.
3.3.4 Vibration. The self-locking fastener shall be subjected to and pass the vibration test
for 30,000 cycles as specified in 4.4.5. For qualification purposes, the activity responsible for
qualification may waive the vibration requirement for thread sizes greater than .500 inch provided
the .500 inch thread size having the same type locking element has passed the vibration test. The
vibration test is not required for thread sizes below .190.
3.4 Reusability. The self- locking fastener shall be capable of 5 seated cycles without
damage to either the nut or bolt threads (see 4.4.2d through f and 4.4.6).
3.5 Identification.
4
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business