TM
55-6680-234-40
SECTION IV
FINAL TEST PROCEDURES
ble 9. In event of failure of test, refer to
14. Test Conditions
paragraph 13m of Section III, Reassembly.
Conduct the following tests at atmospheric
pressure (approximately 29.92 in. Hg.) and at
room temperature (approximate 25C ).
for friction error as follows: Adjust genera-
tor to set the engine pointer at the 1000,
3000, and 6300 RPM indications. At each in-
15. Tests
dication, take twO readings, the first before
Perform the following tests:
and the second after the indicator is vibrated
a. Starting. Connect an indicator generator
or lightly tapped. The difference between the
MS25038-4 each receptacle of the indicator
two readings represents friction error which
under test. Increase the indicator generator
shall not exceed 70, 30, and 30 RPM, respec-
shaft speed from 0 to 150 RPM. Each pointer
tively, at the three test points specified. The
must move from its zero calibration mark in-
error can be determined by observing the dif-
dicating that its motor has started. The indi-
ference in generator RPM required to pro-
cator may be vibrated or lightly tapped during
duce these changes in indication (20 RPM of
the test. In event of failure of test, refer to
generator is equal to 30 engine RPM). In a
paragraph 13k of Section III, Reassembly.
similar manner, check the rotor pointer for
b. Scale Error. With an indicator generator
friction at the 40, 200, and 310 RPM indica-
connected to each receptacle of the indicator,
tions. Friction errors at these test points shall
energize the indicator generators, one at a
not exceed 3.5, 1.5, and 1.5 RPM, respective-
time, to check the scale error of each pointer
ly. This error also can be determined by ob-
at the test points specified in the calibration
serving the difference in generator RPM re-
quired to produce these changes in indication
(20 RPM of generator is equal to 1.5 rotor
the tests with speeds increasing and then with
decreasing speed. Determine errors either
RPM).
by setting the generator at a nominal speed
e. Pointer Oscillation. Maintain the indica-
and observing the indicator pointer reading or
tor generator driving the engine pointer at
by setting the indicator pointer at a graduation
any constant speed above 800 RPM indi-
mark and observing the generator speed. The
cated. The engine pointer shall not oscillate
friction error test of d below can be con-
over a range greater than 50 RPM. Now
ducted simultaneously with this test. In event
maintain the generator driving the rotor point-
of failure of test, refer to paragraph 13m of
er at any constant speed above 40 RPM indi-
Section III, Reassembly.
cated. The rotor pointer shall not oscillate
c. Pointer Alignment. Connect an indicator
over a range greater than 2.0 RPM.
generator to each receptacle of the indicator.
f. Position Error. Operate the indicator at
Operate the generators simultaneously; set
an indicated engine speed of 6200 RPM and
them at the test points specified in table 9.
at an indicated rotor speed of 304 RPM. The
The difference between the readings of the
change in these indications, caused by rotat-
two pointers of the indicator shall not exceed
ing the indicator from the normal position to
the pointer alignment tolerance as noted in ta-
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