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|  MIL-P-70679 (AR)
4.4.5.5 Hydrotest. Projectile bodies shall be tested using
equipment capable of performing the test accurately and
consistently. During the test the pressure will be applied
gradually until the required minimum pressure is reached and held
for five (5) seconds, minimum. The equipment shall be calibrated
prior to the start of each day's operation and at intervals of not
over 4 hours of continuous operation. It shall also be calibrated
prior to restarting the operation after a lay-off of three hours or
more. If it has been found that the equipment is out of calibration
in such a direction that the pressure was actually lower than
required by the test, the bodies tested since the last satisfactory
calibration shall be retested after the calibration error has been
corrected. Projectile rupture, cracking, leakage or bulging during
the test shall be cause for rejection of the body. The test fixture
shall not restrict the projectile body from expanding longitudinally
or radially under pressure. Protective barriers should be installed
where applicable to shield operators and material from metal
fragments which may come from defective projectiles that fail the
test (see 4.4.3.3).
4.4.5.6 Maximum average pressure test. The metal parts
assemblies provided by Table I and 4.4.2.3 for this phase shall be
inert loaded to the service weight and assembled with dummy fuzes
into complete rounds. Firing tests will be conducted in a mortar
for which the round is standard, the tube of which will have a
minimum of 25 percent life remaining based on current mortar tube
condemnation criteria. The propelling charge will be adjusted to
obtain 109 to 117 percent of the maximum average pressure (10,080
psi) of the propellant when fired at 70F. See MIL-P-63194. The
test shall be performed at a Government proving ground in accordance
with applicable U.S. Army TECOM acceptance test procedures.
Photographic equipment will be set up near the gun muzzle to record
the flight of the projectile to determine compliance with 3.9 on the
initial production sample, on the first five production lot samples,
and on three (3) consecutive lots when a new mill heat of steel is
introduced into production. An attempt will be made to recover at
least 60 percent of the projectiles fired in this phase. The
recovered projectiles will be examined to determine compliance with
3.9.
5. PACKAGING
Packaging, packing and
5.1 Packaging, packing and marking.
marking shall be in accordance with requirements of dwg. 7548319.
6.
NOTES
6.1 Visual examination qualifications. When compliance with
the applicable classification of defect is in doubt as a result of
visual examination, this characteristic shall be measured or gaged
to determine acceptability.
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