MIL-DTL-48557B
4.4 Environmental.
4.4.1 Storage temperature. The mount shall be placed in the test chamber and the
temperature of the chamber reduced gradually to -60 ± 5°F and shall remain at this
temperature for a minimum of 4 hours. At the completion of this 4 hour period, the mount
shall be removed from the environmental chamber and inspected for signs of physical
failure or damage. The mount shall be placed back in the environmental chamber and the
temperature shall then be gradually raised to +160 ± 5°F and the mount shall remain at this
temperature for a minimum of 4 hours. At the completion of this 4 hour period, the mount
shall be removed from the environmental chamber and inspected for signs of physical
failure or damage. The mount shall be placed back in the environmental chamber and the
temperature of the test chamber shall be gradually reduced to room ambient temperature
(+60°F to +90°F) at which time the mount shall be removed from the test chamber. The
mount shall then meet the requirements of 3.5 through 3.11 inclusive. (See 6.6)
4.4.2 Operating temperature. The mount shall be placed in the environmental
chamber and the temperature of the chamber reduced gradually to -50 ± 5°F. The mount
shall remain at this temperature for a minimum of 4 hours. At the completion of this 4
hour period, and while at -50 ± 5°F, the mount shall meet low temperature requirement
listed in 3.9. Upon completion of this portion of the test, the mount shall then be placed
back in the environmental chamber and the temperature shall be raised gradually to +145 ±
5°F. The mount shall remain at this temperature for a period of 4 hours. At the completion
of this 4 hour period, and while at +145 ± 5°F the mount shall meet the high temperature
requirement listed in 3.9. Upon completion of this test, the mount shall be returned to the
environmental chamber and the temperature shall be gradually reduced to room ambient
temperature (+60°F to +90°F) at which time the mount shall be removed from the test
chamber and shall meet the requirements as specified in 3.5 through 3.11 inclusive. (See
6.6)
4.4.3 Shock. The M171A1 mount shall be mounted to the test equipment utilizing
the keyway and four mounting bolts torqued to 85-90 foot-pounds, a M17A1 quadrant,
13005101, and a M137A2 telescope, 12984713, or equivalent weight and center of gravity
simulators shall be mounted to it in the designated locations, and then it shall be subjected
to the shock requirements in accordance with 3.4.3. Fixture 11747196 may be used to
adapt the mount to the shock test equipment. Upon completion of the shock test, the mount
shall be examined and inspected to meet the requirements of 3.5 through 3.11 inclusive.
4.4.4 Vibration "A". The mount shall be mounted utilizing the keyway and four
mounting bolts torqued to 85-90 foot-pounds and then subjected to the vibration
requirements in accordance with 3.4.4. Fixture 11747196 may be used to adapt the mount
to the vibration test equipment. Upon completion of the vibration test, the mount shall be
examined and inspected to meet the requirements of 3.5 through 3.11 inclusive.
4.4.5 Vibration "B". The mount shall be mounted utilizing the keyway and four
mounting bolts torqued to 85-90 foot-pounds and then subjected to the vibration
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