(2) Replacement Factor (column 3b).
National Stock Numbered maintenance
This column reflects the replacement factor assigned to each
repair part on its first appearance in the publication. The
replacement factor, expressed as a decimal, indicates the average rate at which the type of item so cod-
ed has been used by Marine Corps field units or the rate at which design engineers anticipate the item
will fail, wear out, or otherwise require replacement. All computations are based on a replacement
period of one year. Therefcre, a replacement factor of 0.08, applied to an item in this stock list, indicates
that eight out of every one hundred of such items used in the end item of equipment to which this
publication pertains, is predicted to need replacement in one year. Likewise, 0.004 reflects that four out
of every thousand in use are predicted to require replacement in one year, while 2.0 shows that every one
in use is predicted to be replaced twice during each year.
(a) Initial authorized stockage levels of consumable and salvageable items for an organization are
to be computed for predicted consumption based on the number of items employed and/or supported by
an organization within the number of days for which stockage is authorized. In computing Garrison
Operating Stock or Mount-Out, authorized levels can be determined by the requiring Marine Corps unit
by multiplying the replacement factor times the quantity used per equipment, times the number of end
items employed by the using organization, or supported by the service organization, times the autho-
rized day level expressed in months and divided by 12. Specific formulas and examples are provided in
Marine Corps Order, MCO P4400.79.
The replacement factors used in initial stockage computations, should be revised, if warranted, after
significant usage is experienced in accordance with the guidelines of MCO 4400.32A. The following for-
mula replacement factor, X represents actual usage experience (1 year), A represents the applica-
tion per equipment, and B represents the number of equipments supported.
(b) Initial allowances for maintenance float items (recoverability codes R and D) for the FMF
and appropriate posts and stations are as furnished by Initial Issue Actions.
Changes to maintenance replacement rates resulting from actual usage may require recomputation
of maintenance float allowances by holding units. Any required recomputation of maintenance float
allowances will be made in accordance with MCO 4000.6.
(c) The replacement factor for same as (S/A) items is indicated upon the first appearance of the
item in the major combination, component or assembly.
d. (ALL) National Stock Number (Column 4). Indicates the National Stock Number assigned to the
item and will be used for requisitioning purposes.