MIL-PRF-81975C
threads shall not be used.
3.7.2.1 Locking of threaded parts. All threaded parts shall be positively locked by safety
wiring, self-locking nuts, or other approved methods. Safety wiring shall conform to
NASM20995 and shall be installed in accordance with NASM33540. Self-locking nuts shall
conform to NASM25027 and shall be used in accordance with NASM33588. The use of lock
washers, set screws, cotter pins, or staking shall not be permitted unless specifically approved by
the qualifying activity.
3.7.3 Weight. Maximum weight of the couplings without the fairing shall be as follows:
a. MA-2 couplings shall not weigh more than 18 pounds.
b. MA-3 couplings shall not weigh more than 18 pounds.
c. MA-4 couplings shall not weigh more than 22 pounds.
3.7.4 Finishes. The coupling finish shall be smooth and free from sharp edges. Surface
roughness, indicated on figure l, sheet 1 of 3, shall be as specified in accordance with ASME-
B46.1.
3.7.5 Reliability. The coupling shall be designed and constructed in a manner that will
ensure the highest degree of operational reliability under all service conditions when operating
with any qualified nozzle.
3.7.6 Maintainability. The coupling shall have the minimum number of parts consistent
with reliability. It shall permit easy assembly, disassembly, and location of trouble sources. It
shall be maintained with tools and equipment normally available commercially by service
maintenance personnel with a minimum of training.
3.7.7 Interchangeability. All parts having the same manufacturer's part number shall be
functionally and dimensionally interchangeable in accordance with MIL-I-8500. The item
identification and part number requirements of ASME-14.100 shall govern the manufacturer's
part numbers and changes thereto.
3.7.8 Dimensions. MA-2 coupling dimensions shall be in accordance with MS24355.
Coupling dimensions for MA-3 and MA-4 couplings shall be in accordance with figure 1.
3.7.9 Lubrication. The coupling shall operate satisfactorily without requiring lubrication,
other than the fluid being transferred.
3.7.10 Identification of product. Equipment, assemblies, and parts shall be marked for
identification in accordance with MIL-STD-130. The identification shall be permanent and shall
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