TM 55-1520-240-23-1
1-7.
AUTHORITY FOR SUBSTITUTION
Substitution or interchange of items or material for maintenance of Department of the Army aircraft shall not be
authorized, nor shall orders be issued for shipment. Substitution or interchangeability shall be only by US Army
Aviation and Missile Command.
1-8.
CALIBRATION
Within the scope of this manual there are no helicopter components, accessories, or instruments that require
calibration. Special tools and test equipment shall be calibrated as specified in TB 750-25, Army Metrology and
Calibration System.
1-9.
EXPLANATION OF CHANGE SYMBOLS
Changes, except as noted below, to the text and table and including new material on added pages, are indicated
by a vertical line in the outer margin extending close to the entire area of the material affected. An exception
is that pages with emergency markings, which consists of black diagonal lines around three edges, may have the
vertical line or change symbol placed along the inner margins. Symbols show current pages only. A miniature
pointing hand symbol is used to denote a change to an illustration. However, a vertical line in the outer margin,
rather than miniature pointing hands, is used if the illustration is new, or when there have been extensive changes
made. Change symbols are not used to indicate changes in the following:
a.
Introductory material.
b.
Indexes and tabular data where the changes cannot be identified.
c.
Blank space resulting from the deletion of text, an illustration, or a table.
d.
Correction of minor inaccuracies, such as spelling, punctuation, relocation of material, etc. unless such
correction changes the meaning of instructive information and procedures.
1-9.1. AIRCRAFT MODIFICATION (ECP/MWO) RETROFIT INFORMATION
Throughout this manual, black squares containing white numerals are used to distinguish information relating to
helicopters modified by an MWO or ECP. Refer to Helicopter Configuration Legend on the following pages for
specific modifications and effectivities relating to each numeral. A list of delivered helicopters serial numbers is
included with the legend.
Information pertaining only to unmodified helicopters is identified by the appropriate effectivity symbol preceded by
WITHOUT. For example, (WITHOUT 4 ) indicates that the information that follows is applicable only to helicopters
not modified by ECP D018. Information pertaining only to helicopters that have been modified by ECP D018 is
preceded by (WITH 4 ). All information not preceded by an effectivity symbol is common to all helicopters.
The following helicopter Designation Legend pages are solely for user convenience. They have no official status.
DELIVERED HELICOPTER SERIAL NUMBERS
81-23382
through
81-23389
82-23762
through
82-23780
83-24102
through
83-24125
84-24152
through
84-24187
85-24322
through
85-24336
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