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|  MIL-T-45688D(MU)
of MIL-F-13926 and the conditions of 3.5.2. The telescope shall be ex-
posed to each temperature extreme specified in 3.5.2 for a period of five
hours. At the end of each five hour period, and while still at the temp-
erature extreme, the telescope shall be subjected to the applicable test
of 4.6.12 through 4.6.14 inclusive. The telescope shall conform to the re-
quirements of 3.5.2. Caution shall be exercised during this test to avoid
subjecting the telescope to thermal shock.
4.6.3 Vibration.- Vibrating equipment capable of providing the ampli-
tude and frequency specified in 3.5.3 shall be utilized for this test. The
vibrating equipment shall also be capable of vibrating the telescope along
three mutually perpendicular axes while the telescope is maintained in a
horizontal position as depicted in the lower view on sheets 1 and 2 of
Drawing F8574700. The telescope shall be hortizontally mounted on the vi-
bration table by means of an adapter. This adapter shall immobilze the
objective tube assembly, and the offset tube assembly, so that the articu-
lating joint assembly is immobilized in its midpoint of the articulating
range. The telescope shall be vibrated in accordance with Procedure IX,
Part I of MIL-STD-81O, except that the frequency, frequency cycling, and
amplitude of the vibration shall be as specified in 3.5.3. Upon comple-
tion of the vibration cycling the telescope shall be subjected to the
tests specified in 4.6.4.
4.6.4 Examination.- Subsequent to vibration the telescope shall be
thoroughly examined for physical defects resulting from poor workmanship
and materials to determine conformance with 3.5.3, prior to being subjected
to the remaining tests specified herein. A visual examination shall be made
for missing or damaged parts. A tactile examination shall also be conducted
to determine looseness or improper functioning of moving parts such as the
articulated joint, diopter adjustment, reticle transfer lever, etc.
An audible examination shall be made of the telescope by shaking it and
listening for loose internal parts or broken optical components, such as
lenses, prisms, retitles, etc. Any one of the possible defects defined
above shall be cause to consider a telescope defective. Telescopes which
have passed the above examinations shall be subjected to the tests specified
in 4.6.4 through 4.6.15 inclusive to determine overall compliance with 3.5.3.
4.6.5 Sealing.- The internal pressurizing of the telescope to test
sealing shall be performed with special testing equipment conforming to
4.5.2.3.1. The pressure shall be applied through the Valve Assembly.
Pressurize the telescope with dry nitrogen gas to 5.0 0.10 psig in accord-
ance with the procedure for internal pressure testing on Sheet 1 of Drawing
F8565556. The dry nitrogen gas shall have a dew point at least as low as
minus 25F. The applied pressure shall be retained for a minimum of 2 hours.
Within the first 60 minutes of this 2 hour time period, the telescope eye-
piece housing assembly shall be elevated through a minimum of 3 full excur-
sions of the articulated joint assembly, the reticle transfer lever shall be
repositioned a minimum of 3 times and the diopter adjustment shall be rotated
through a minimum of 3 full excursions (CW stop-to ccw stop-to cw stop), of
its rotational range. Any evidence of leakage in the telescope at the end
of the 2 hour time period, shall not exceed the tolerance specified in 3.6,
as measured on the pressure gauge of the testing equipment.
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