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| MIL-S-8551O(AS)
elongation readings are not continuous, a reading shall be
taken specifically at the design load of 4,000 pounds. Loading
shall continue to failure. Pointers shall be affixed to the
webbing, as close as possible to the end fitting, and shall be
monitored during the test. Structural failure of any component
or elongation in excess of 10 percent at a load equal to or
less than 4,000 pounds design load shall be unacceptable.
Shoulder harness assembly test. The shoulder harness assembly
e.
shall be tested with the inertia reel in a "locked" position
and attached to a suitable fixture. The shoulder harness end
fittings shall be "plugged" into the buckle and the buckle
shall be attached to a movable fixture. The webbing lengths
shall be adjusted to fit a 95th-percentile occupant. The test
shall be started from an initial preload of 100 pounds The.
fixtures shall be separated at a rate of 2 in./min. The
elongation and applied load shall be measured continuously,
or at intervals not to exceed 0.5 inch of elongation. If
load-elongation readings are not continuous, a reading shall
be taken specifically at the total design load of 4,000 pounds.
Loading shall continue to failure. Load-elongation data shall
be recorded for both total elongation, including elongation of
webbing on the reel spool, and free webbing length exclusive
of elongation of webbing on the reel. Pointers shall be affixed
to the webbing, as close as possible to the reel spool and on the
movable fixture, and shall be monitored during the test.
Structural failure of any component or elongation in excess of
10 percent exclusive of elongation of webbing wrapped around the
reel spool at a load equal to or less than the 4,000 pound
design load shall be unacceptable. Elongation of the free length
of harness shall be computed by subtracting the elongation measured
within the reel from the total. In the event that an inertia
reel is not specified as a component of the shoulder harness
assembly, the test procedure shall be conducted with the appropri-
ate seat back/shoulder harness attachment fittings replacing the
inertia reel unit.
Aduster tests. Each different adjuster in the harness Each different adjuster in the harness
f.
assembly shall be tested as follows:
(1) Adjustment load. With no load other than the adjustment re-
action load, webbing shall be drawn through each adjuster at a
rate of 20 2 in./sec and the adjustment force measured. The
adjustment force shall not exceed 30 pounds. This test shall be
repeated 20 times.
(2) Abrasion test. With no load other than the adjustment reaction
load, webbing shall be cycled through its adjuster 5,000 times.
The webbing shall then be tested to demonstrate that it can
still withstand the design load stated in table 11, and that no
slippage of the webbing occurs at the adjuster due to abrasion.
The test shall be conducted for each different webbing/adjuster
combination.
g. Buckle tests. Cycle the buckle release with fitting insertions
5,000 times followed by test a and d above.
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