When the urgency of the situation dictates,
operational commanders may extend the short-cycle
An assembly-level item is a component that
maintenance period for mines afloat. However, three
consists of one or more parts that are designed to
factors must be considered in this extension:
function as an end item in a mine assembly.
1. The expected life of the mine
Class-B criteria must be performed on
2. The resistor plug installed in the sterilizer
assembly-level items. Visual inspections, parts
3. The storage time of the batteries
class-B criteria. The required intervals for these
c r i t e r i a a r e d e t a i l e d i n NAV S E A S W 5 5 0 - F O -
To calculate the extended stowage time for a mine,
PMS-010. At such times, however, whether the job
apply these factors to the following formula:
sheet for an assembly-level item contains only one,
(X-Y) Z = Extended stowage time X= Y= Z=
two, or all three of the criteria, it must be verified that
such items meet the job sheet specifications if they are
to be accepted into service use.
(X-Y) ) Extended stowage time
Tw o s p e c i f i c t e r m s a r e a p p l i c a b l e t o t h e
X = Expected life (in months) of the mine
performance of these criteria:
Functional test: The technician uses test
Y = Value (in months) of the resistor plug
i n s t r u m e n t s t o ve r i f y s p e c i fi c o p e r a t i n g
stalled in the mine
Z = Effective stowage time of the mine
Visual inspection: Testing is performed by sight,
feel, or manipulation, without the use of the test
NOTE: If the result is less than 1, no extended
time is allowed.
A c c o r d i n g t o t h e p r o v i s i o n s o f NAV S E A
SW550-FO-PMS-010, assembly-level components
are divided into four groups, commensurate with the
maintenance necessary to ensure reliable operability.
Long-cycle maintenance is performed to confirm
NAVSEA SW550-AA-MMI-010 provides a listing of
the operability of designated assembly-level items
all assembly-level components and assigns each to one
of four groups, indicating the maintenance
installed in mines stowed in assembly configurations
requirements for each.
A, B, C, D, and E. This maintenance must be
performed periodically according to table 3-2 of
Accordingly, an assembly-level component is
assigned to a particular maintenance group based on
NAVSEA SW550-FO-PMS-010. These items are
the following factors:
listed in Mine Components, Description and Class-B
Design characteristics of the component
Criteria, NAVSEA SW550-AA-MMI-010.
Function of the component
Shelf life of the material used in its manufacture
A 10 percent random sample of explosive sections
Service history (as determined by fleet-
of Mine Mk 56 assembled to configurations D and E
originated data reports)
need only be subjected to class-B criteria every 6 years.
However, if the 10 percent sample contains a reject, the
lot from which the reject was taken must be subjected
cycle of the weapon in which the component is
to 100 percent inspection. On the other hand, if all
items in the sample meet the inspection criteria, the
Assembly-level items in the four maintenance
maintenance cycle can be extended for 6 additional
groups designed or maintained as spares must receive
years. These items are identified in the maintenance
the same maintenance as items in assembled mines.
tables of NAVSEA SW550-AA-MMI-010.
Maintenance of spares may be performed anytime