This Technical Bulletin (TB) prescribes the aircraft components, sub-components, modules and/or parts for which a requirement has been established to
maintain and collect maintenance and historical data. This bulletin supersedes the previous TB 1-1500-341-01, dated Jun 2004, and incorporates up to
and including Change 52 to the Unit Level Logistics System-Aviation (ULLS-A) Master Files.
All activities, maintaining, stocking, storing, issuing, modifying, repairing and/or overhauling aircraft, aircraft components or assemblies assigned to the
Department of the Army will comply with the provisions of this TB. This is to include all military activities, active U.S. Army units, U.S. Army National Guard
units, U.S. Army Reserve units, depots and commercial contractors.
a. End Item. A final combination of end products, components, parts, and/or materials that is ready for its intended use (e.g., Aircraft).
b. Major/Higher Component. A combination of subassemblies, assemblies, components, modules, and parts connected in such a manner as to be a self-
contained unit which, although part of an end item, is capable of operating independently of the end item (e.g., Engine T-53).
c. Component/Module. A combination of two or more sub-components or parts, mounted together in manufacture, that may be tested, replaced or repaired
as a unit (e.g., starter, generator, fuel pump, line replaceable unit (LRU), printed circuit board). The term "module" is normally associated with electronic
equipment and/or engines.
d. Sub-component (Subassembly). A combination of two or more parts that function together as a portion of a complete component (e.g., Fuel Control
e. Part. An item which cannot be disassembled or is of such design that disassembly is impractical,(e.g., Gear, Bolt).
f. Retirement Change ("RC") Item. An item that has been assigned a safe Maximum Allowable Operating Time (MAOT) since new, that it can safely be
operated before it must be removed from service, mutilated, and lost to the Army inventory. This item can be repaired prior to reaching its MAOT, but normally
will not be overhauled. The item must be removed from service when the MAOT is reached.
g. Time Change ("TC") Item. An item that has a fixed operating Time Between Overhauls (TBO). The time is based on safety and/or design limitations.
The item must be replaced with a new or overhauled item after the specified time. The item will then be overhauled at a depot level facility.