MIL-DTL-5498G
4.6.7.4 Fluid leakage test for conformance tests. This test shall be conducted in a manner
similar to that described in 4.6.7.2 except that pressure shall be applied for a period of
3 minutes only.
4.6.8 Seizing of parts. All accumulators shall be tested for seizing of parts throughout
the temperature range of 275 °F to -65 °F. Operation of the unit during this test can be
accomplished by removing the seals from the piston and then manually sliding the piston through
its entire stroke by use of suitable push rods through the oil and air ports. If fluid is used to
accomplish the cycling, the entire amount of fluid used shall have reached the proper stabilized
temperature. The method used shall be recorded in the test report. The assembly shall be
maintained at a temperature not less than 275 °F for at least 6 hours, after which two cycles of
operation shall be made. The assembly shall then be rapidly cooled to a temperature not greater
than -65ºF. The sliding parts shall be operated at least 10 full cycles of operation spaced
throughout the cooling period and at least two complete cycles after the 24-hour period. The
assembly shall then be rapidly warmed up to room temperature and operated at least 10 full
cycles of operation spaced throughout the warming period. There shall be no evidence of
malfunctioning or seizing of parts caused by thermal contraction or expansion of the parts.
4.6.9 Non-destructive inspection. All parts made of ferrous materials shall be subjected
to magnetic inspection in accordance with ASTM E 1444. All aluminum parts shall be penetrant
inspected in accordance with ASTM E 1417. These tests shall reveal no cracks or other injurious
defects.
4.6.10 Burst pressure. The burst test shall be conducted on only one of the two
qualification test units. The piston shall be in approximate mid-position and the gas chamber
shall be filled with fluid. With the fluid and unit temperature stabilizing at a minimum
temperature of 275 °F, the pressure shall be applied at the fluid port from a maximum pressure
source of 25,000 psi until a pressure of 12,000 psi is obtained. The accumulator shall not rupture.
4.6.11 Fragmentation. Resistance to fragmentation should be evaluated by test. This test
shall be conducted on only one of the two qualification test units. For accumulators three inches or
less in diameter, the ammunition should be .30-caliber M-2 armor piercing. For all other sizes, the
ammunition should be .50-caliber M-2 armor piercing. The accumulator shall be pre-charged to
1,200 psi gas pressure, charged to 3,000 psi fluid pressure. and shall be hit with a .50 caliber
projectile fired at a range of 25 yards to 50 yards. The projectile shall have a muzzle velocity of
2,700 feet per second to 2,900 feet per second. The projectile shall be tumbled so that the .30-
caliber shell produces an "in" hole at least 0.25 inch wide by 0.625 inch long, and the .50-caliber
shell should produce an "in" hole at least 0.50 inch wide by 1.50 inches long. The accumulator
shall be supported in a manner similar to a typical aircraft mounting. Attached to the fluid port
shall be a length of tubing with a shutoff valve located 3 feet from the port. The projectile shall
be directed so that it will hit the fluid side of the accumulator approximately midway between the
piston and the mounting strap. The accumulator, when struck by gun fire as specified, shall
remain in one piece and the greatest dimension of the opening (cut and tear) created by the
projectile shall not exceed the dimensions of the hole (cut) created by the projectile by more than
3 inches in any one direction. Cutting shall be considered as the actual section of the accumulator
cut by contact with the projectile and a tear shall be considered as an extension beyond the cut.
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