TM 55-6610-247-40
SECTION V
DIFFERENCE DATA SHEETS
reading shall be taken at 500. 1.500 and 3.000 feet in
5-1.Overhaul instructions for the types included in this
addition to the other test points.
section are the same as the procedures for the specified
type covered in the preceding sections of this manual.
except for the differences noted herein.
15 minutes after altimeter has been first subjected to
5-2. Difference Data For Sensitive Altimeter, Part
pressure corresponding to upper limit of scale in scale
Numbers 1845X403, 1845X403D, and 1845X403DF.
error at room temperature test, pressure shall be
The instructions contained in the preceding sections
increased at a rate corresponding to a decrease in
of this technical manual apply except for the differences
altitude of approximately 3,000 feet per minute until
noted in this data sheet.
pressure corresponding to first test point given in table 5-
a. Leading Particulars. Leading particulars are the
2 is reached Altimeter shall remain at this pressure for at
same as for part number 671CPX403TDF, except for the
least 5 minutes but not more than 15 minutes. before test
omission of inner and outer setting markers.
reading is taken. After reading has been taken, pressure
b. Disassembly. Disassembly is the same as for part
shall be further increased at specified rate until pressure
corresponding to second test point given in table 5-2 is
number 671CPX4037DF, except for the omission of
reached. Altimeter shall remain at this pressure for at
inner and outer markers.
c. Modification Criteria. Modification criteria is the
least 1 minute but not more than 10 minutes before test
reading is taken. After reading has been taken, pressure
same as for part number 671CPX4-037 except the part
shall be further increased at specified rate until
numbers are reidentified as follows:
atmospheric pressure is reached. Reading of altimeter at
1815X403 to 1845X403DF
either of two test points shall not differ from reading of
184SX403D to 1845X403DF
altimeter for corresponding altitude in scale error test, by
d. Testing. Testing is the same as for part number
more than tolerance given in table 5-2. Not less than I
671CPX4-037DF except as follows:
minute and not more than 5 minutes after completion of
(1) Zero Setting Test. Altimeter shall be subjected
hysteresis test, pointers shall have returned to their
to atmospheric pressure. Pressure scale shall be set,
original reading, corrected for any change in atmospheric
successively, at values listed in table 5-1. Altimeter shall
pressure. within tolerance given in table 5-2 as third test
be tapped or vibrated lightly and pointer indication noted.
point.
After series of readings has been recorded. difference
Table 5-1. Zero Setting .Mechanism
between readings at setting of 29.92 and each other
1845X403DF
setting shall be found. These differences shall be
recorded and compared with values in CORRECT
SETTING
CORRECT
DIFFERENCES column. Recorded values shall not differ
PRESSURE SCALE
DIFFERENCES
from correct differences by more than 25 feet at any
28.5
1,340
setting.
23.92
0
(2) Scale Error Test. The room temperature scale
30.9
893
error test is the same except that
Table 5-2. Hysteresis--1845X4-03DF
EQUIVALENT
STANDARD
ATMOSPHERIC
PERMISSIBLE
TEST POINTS
ALTITUDE
PRESSURE
VARIATION
First point
25,000
11.10
150
Second point
20,000
13.75
150
Third point
Ground level
60
5-1
