determined by the applicable Mission Essential
Subsystem Matrix, because of organizational or
intermediate maintenance requirements.
(2) Not Mission Capable Supply
(NMCS)The material condition of an aircraft
or training device that indicates it is not capable
of performing any of its assigned missions because
maintenance required to clear a discrepancy
cannot continue due to a supply shortage.
METER READINGMeter readings, as used
in this manual, apply to only those items that have
a clock/meter installed. Readings will be in time,
cycles, starts, etc., to the nearest whole number.
Recording of meter readings on source documents
will be prefixed with the letter A4.
MISHAP, AIRCRAFTA naval aircraft
mishap is an unplanned event, or series of events,
directly involving naval aircraft that results in
(1) ten thousand dollars or greater cumulative
damage to naval aircraft, other DOD or non-
DOD aircraft, and property. Property damage
includes costs to repair or replace facilities,
equipment, or material; or (2) an injury as defined
in the latest edition of OPNAVINST 3750.6.
MISSION ESSENTIALThose functions
and equipment authorized and assigned to
approved combat and combat support forces that
would be immediately employed (1) to wage war
and (2) to provide immediate support combat
MISSION ESSENTIAL SUBSYSTEM(S)
Those subsystems of an aircraft or training device
required to perform the designated missions as
determined by use of the applicable Mission
Essential Subsystem Matrix. See the latest edition
of OPNAVINST 5442.4.
MISSION ESSENTIAL SUBSYSTEMS
MATRICES (MESMs)Issued by the latest
edition of OPNAVINST 5442.4. This instruction
lists, for each model, the equipment systems/
subsystems that must be on board and in working
order before an aircraft can qualify as mission
NAVAL AVIATION MAINTENANCE
DISCREPANCY REPORTING PROGRAM
(NAMDRP)A program by which all hazardous
deficiencies in material, publications, substandard
workmanship, and improper quality assurance
procedures are reported.
NAVAL AERONAUTIC PUBLICATIONS
INDEX (NAPI)A six-section index of all
aeronautic publications, changes, technical
directives, and forms under the cognizance of
NON-RFISee READY FOR ISSUE (RFI).
NOTICESDirectives of a one-time nature
or those applicable for a brief period of time.
Each notice contains provisions for its own
cancellation. Notices employ a subject classi-
fication numbering system and are part of the
Navy Directive System.
OFF-EQUIPMENT WORKAll mainte-
nance actions performed on removed, repairable
components, usually at the IMA.
ON-EQUIPMENT WORKThose mainte-
nance actions accomplished on complete end
items; for example, aircraft, SE, and removed
OPERATING AIRCRAFTIncludes those
aircraft in operating status in operating command
custody. An aircraft is in an operating status
whenever it is filling an authorized operating
allowance. An aircraft reported in any of the
A-status codes is in an operating status. Operating
status aircraft are always in the reporting and
physical custody of the operating unit to which
assigned. An aircraft that moves to a rework
facility for purposes of rework will leave operating
status, although it may remain in the reporting
custody of the operating unit.
OPERATIONAL SERVICE AGEThe
number of operational service months an aircraft
has completed. See OPERATIONAL SERVICE
OPERATIONAL SERVICE LIFEThe
planned total life of an aircraft is always measured
in terms of operational service months. The latest
edition of OPNAVINST 3110.11 contains opera-
tional service life factors for each model aircraft.
OPERATIONAL SERVICE MONTHOne
monthly increment of operational service life;
aircraft age is programmed in terms of operational
service months. An aircraft completes operational
service life upon the accumulation of the number
of operational service months prescribed by the
latest edition of OPNAVINST 3110.11. Each of