MIL-STD-1798 Mechanical Equipment And Subsystems Integrity ProgramThe purpose of this standard is to describe the general process to achieve and maintain the physical and functional integrity of the mechanical elements of aircraft systems. The goal of this integrity program is to achieve the desired level of safety and aircraft availability at the most economic cost across the life cycle of the weapon system. This standard allows the process to be tailored in a competitive environment to meet specific equipment, subsystem, and/or system requirements. The Mechanical Equipment and Subsystems Integrity Program MECSIP is implemented in the planning process and continued until retirement of the system.

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MIL-STD-1798C

3.61  Time Change.

Time Change is the replacement of a component at a specified service I time interval. Time

Change is also referred to as "hard time task" in RCM.

3.62  Time Change Item (TCI).

Items designated as TCI are replaced at specified intervals.  The primary objective of a time change is to achieve maximum utilization of components consistent with the economic operation of the weapon system, support systems, and equipment without jeopardizing flight or

operational safety.  Time Change Item identifiers are only prescribed for those items that have a measured service life expectancy and display an age-related failure pattern.

3.63  Up-rating.

Up-rating is the process of operating an electrical component outsideIbeyond the manufacturer recommended operating range. This is usually done to minimize design cost or weight or prevent obsolescence. It may have detrimental impacts on component useful life and requires careful analysis of its application. Example: If the manufacturer specs a diode to operate at 1OV and 5 Amps and it is used in an environment of 13V and 7 Amps, it is said to have been up- rated for that application.  Uprating is not limited to electric components, but frequently is

applied to electric components.

3.64  Usage.

Usage is defined as the operational parameters critical to function, performance, and service-life of the system and equipment (e.g., missions, duty cycles, loading, environments, etc.).

3.65  Work Unit Code (WUC) Manual.

The WUC Manual is a manual which identifies the code assigned to each commonly-performed maintenance task, allows maintenance on specific components to be tracked, and causes for not mission capable time, maintenance man-hours, etc., to be recorded.

3.66  Acronyms.

AC                Advisory Circular

ACI               Analytical Condition Inspection

AMARG       Aerospace Maintenance and Regeneration Group

ATP              Acceptance Test Procedures

ATSRAC      Aging Transport Systems Rulemaking Advisory Committee

AWP            Awaiting Parts

BIT               Built-in Test

CAI               Critical Application Item

CANN          Cannibalization

CEI               Configured End Item

CP                Conductive Path

CSI               Critical Safety Item

DCM            Defense Contract Management

DR               Digital Radiography

EAPAS         Enhanced Airworthiness Program for Airplane System

ECS             Environmental Control System

ES                Equipment Specialist

ESA             Engineering Service Authority

EWIS           Electrical Wiring Interconnect System

EWISIP        Electrical Wiring Interconnect System Integrity Program

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