TM 55-4920-431-23P
Section I. INTRODUCTION
1. Scope.
This manual lists repair parts, special tools, special test, measurement, and diagnostic equipment (TMDE), and other
special support equipment required for performance of aviation unit maintenance (AVUM) and aviation intermediate
maintenance (AVIM) of the Auxiliary Power Unit Electronic Sequence Unit Multi-Purpose Test Set. It authorizes the
requisitioning and issue of repair parts as indicated by the source and maintenance codes.
2. General.
This Repair Parts and Special Tools List is divided into the following sections:
a. Section II. Repair Parts List. A list of repair parts authorized for use in the performance of maintenance. The
list also includes parts which must be removed for replacement of authorized parts. Parts lists are composed of
functional groups in numeric sequence with the parts in each group listed in figure and item number sequence. Bulk
materials are listed in NSN sequence.
b. Section III. Special Tools List. A list of special tools, special TMDE, and other special support equipment
authorized for the performance of maintenance.
c. Section IV. National Stock Number and Part Number Index. A list in National item identification number (NIIN)
sequence, of all National stock numbers (NSN) appearing in the listings, followed by a list in alphanumeric sequence of
all part numbers appearing in the listings. National stock numbers and part numbers are cross-referenced to each
illustration figure and item number appearance.
3. Explanation of Columns.
a. Illustration. This column is divided as follows:
(1) Figure Number. Indicates the figure number of the illustration on which the item is shown.
(2) Item Number. The number used to identify item called out in the illustration.
b. Source, Maintenance, and Recoverability (SMR) Codes.
(1) Source Code. Source codes indicate the manner of acquiring support items for maintenance, repair,
or overhaul of end items. Source codes are entered in the first and second positions of the Uniform SMR Code format
as follows:
1
