MIL-DTL-18240F
1
X8
Sufficient Thread Length =
P
Where P = Thread Pitch
EXAMPLE: .250-28 Thread
1
X 8 =.286in
Sufficient Thread Length =
28
e. First cycle test: During the first tightening of the assembly, the 1st cycle ON
PREVAILING TORQUE (see 6.5) shall be measured and recorded.. Tightening
shall be continued until the required SEATING TORQUE (see 6.5) as specified in
table II for the applicable thread size and pitch is developed. The axial clamp load
shall be reduced to zero by backing the self-locking fastener or test nut off, until
the spacers are free to rotate. Following the removal of the axial clamp load, the
1st cycle OFF PREVAILING TORQUE (see 6.5) shall be measured during the
next 360 degrees of rotation and recorded. The self-locking fastener and test nut
shall be disassembled until the locking element is disengaged. The driving speed
shall not exceed 30 RPM.
f. Second through fifth cycle tests: The self-locking fastener and test nut shall be
reassembled, seated, and disassembled four more times following the same
procedure as the 1st cycle test. The ON and OFF PREVAILING TORQUE shall
be measured and recorded for each cycle. Sufficient time shall elapse between
torquing cycles to prevent overheating of the test assembly. During the torque test
the temperature shall not be grater than 75°F above the starting temperature.
g. For qualification testing any torque value determined to be in excess of the
limitations of table II constitutes failure of this test. For quality conformance
testing determine whether the lot passes or fails in accordance with table IX
or table X.
4.4.3 High temperature torque.
a. Assemble ten new fasteners as tested in 4.4.2, steps a through d and the on cycle of
step e.
b. Bake the assemblies to 250°F ±10° for 3 hours.
c. Air cool the assemblies to room temperature for a minimum of 1 hour.
8
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business