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|  MIL-T-18847C(AS)
4.6.8.3 Impregnated roving placement. Continuous in-process inspection
and final inspection shall ensure that the impregnated filament wound roving
placement does comply with the requirements of 3.14.8.1.2 through 3.14.8.1.6.
4.6.8.4 Composite construction testing. Materials testing shall be
conducted on samples of the filament wound composite in accordance with the
requirements of 3.14.8.1.7. These tests shall include resin content, Barcol
hardness, and lap shear testing. The lap shear test (see 4.6.8.4.3) shall be
run on the test specimens made in accordance with 4.6.8.1 and to the following
criteria.
4.6.8.4.1 Resin content, An unused section of the tank, such as a door
opening, shall be used to determine the resin content of the cured filament
winding by burning out the resin and weighing the filament that remains. The
resin content shall not vary by more than 5 percent from the original
design.
4.6.8.4.2 Barcol hardness testing. Barcol hardness testing shall be
performed on four areas of each tank. Two tests will be made; one each within
5 Inch radius of each attach lug, and one each within a 10 inch radius of the
access door or fill cap opening of both nose and tail compartments. This test
shall be in accordance with ASTM-D2583 to a minimum Barcol hardness of 40. To
minimize the possibility of skin penetration, the contractor shall conduct
this test to the structural core reinforced areas of the tank.
4.6.8.4.3 Lap shear testing. To ensure a bond between the filament wound
fibers and the tank surface has been achieved, bonding samples of the same
material and thickness, and cleaned by the same process as the tank, shall be
bonded to two groups of impregnated fiberglass fabric. These specimens shall
be used for lap shear testing in accordance with ASTM-D1002 to the requirements
of 3.14.7. There shall be no evidence of failure below the test value.
Sections of the composite shell that are removed for the door cutouts may be
used as alternate test samples for determining the Integrity of the liner bond.
4.6.8.5 Composite sandwich core. The composite sandwich core tanks shall
be inspected before and during application for compliance with the requirements
of paragraph 3.14.8.2.
4.6.8.6 Structural composite curing. Continuous composite curing on all
tanks shall be monitored by observation of processes and controls, and by
process curing control devices with accompanying recorders. Curing control
records shall be maintained as part of the quality control.
4.6.9 Assembled tank weight. The gross weight of the complete fuel tank
dry shall be checked for conformance with the requirements of 3.5.1.4.
4.6.10 Center of gravity. The center of gravity location shall be checked
for conformance with the requirements of 3.5.1.4.1.
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