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Collimation, Post-Vibration/Post-Shock, daylight viewing area |
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|  MIL-H-48620(AR)
examination shall be made for missing or damaged parts. A tactile
examination shall be made for functioning of moving parts, for
irregularities of movement, friction or looseness. An audible
examination shall also be made of the head assembly for loose
internal optical and mechanical components. Any one of the possible
defects defined above shall be cause to consider a head assembly
defective. Head assemblies which have passed the above examinations
shall be subjected to the remaining tests specified in 4.6.3,
4.6.4.4 through 4.6.6 inclusive and 4.6.10 through 4.6.12 inclusive.
4.6.8 Collimation, Post-Vibration/Post-Shock, daylight viewing
area. - Perform this test utilizing the procedure in 4.6.4.1. Record
the collimation measurement. Any difference between the recorded
measurement obtained in this test and the recorded measurement
obtained in 4.6.4.1 shall not exceed the tolerance specified in 3.10
4.6.9 Collimation, Post-Vibration/Post-Shock passive viewi~
area. - Perform this test utilizing the procedure in 4.6.4.2. Record
the collimation measurement. Any differncece between the recorded
measurement obtained in this test and the recorded measurement
obtained in 4.6.4.2 shall not exceed the tolerance specified in 3.11
4.6.10 Sealing. - This portion of the test shall be performed
utilizing a pressure gage capable of reding between 0.25 and 0.50
pound per square inch gage (psig) and a dew point tester. The
following test sequence shall be adhered to. Check the internal
pressure of the head assembly utilizing the pressure gage specified
herein. Then, test the dew point of the interior atmosphere of the
head assembly by means of the dew point testers. Interior atmosphere
of the head assembly shall conform to the requirements of 3.12.
Upon satisfactory completion of this portion of the test, internal
pressurizing of the head assembly shall be performed with special
testing equipment conforming to 4.5.2.3.1. Pressurize the head
assembly with dry nitrogen gas, having a dew point at least as low
as -25F, to 5 0.10 psig in accordance with the procedure for
internal pressure testing on Drawing 8565556. Retain the applied
pressure in the head assembly for a minimum of 2 hours. During the
first hour, the input coupling shall be rotated throught one full
excursion of its articulation range. At the end of the 2 hour
period there shall be no evidence of leadage in excess of 0.2 psi as
indicated on the pressure gage of the testign equipment, to deter-
mine compliance with 3.12. Upon satisfactory completion of the
sealing test, the head assembly shall then be flushed with the dry
nitrogen gas specified herein. The interior atmosphere of the head
assembly shall be periodically sampled through the dew point tester
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