MIL-PRF-26611F
then the direction of rotation reversed and the generator rotated at 4,200 ± 10 rpm for 1 minute.
The generator shall be cooled to 75° ± 10°F, keeping the standard load connected, the drive
shaft shall be rotated at 4,200 ± 10 rpm in the normal direction and the output voltages measured
in accordance with 4.6.4. The voltages shall be 21 ± 2.
4.6.13 Short circuit. The generator shall be connected to the standard load and the drive shaft
rotated at 4,200 ± 5 rpm and the terminal voltages again measured. With the generator still
operating, all three generator terminals shall be short circuited five times at 1 second each time.
The generator shall be cooled to 75° ± 10°F, keeping the standard load connected, and the drive
shaft rotated at 4,200 ± 5 rpm. The output voltages shall again be measured and shall be between
19 and 21.5.
4.6.14 Humidity. At ambient temperature and humidity, the generator shall be mounted in the
test chamber with the shaft in a horizontal position with external connections simulating installed
conditions. The chamber temperature shall gradually be raised to 150°F and the humidity to 95%
over a 2 hour period. This temperature and humidity shall be maintained for 6 hours. After 6
hours, the humidity shall be maintained at a minimum of 85% and the test chamber temperature
shall be reduced from 150° to 85°F over a 16 hour period. The above temperature and humidity
cycle shall be repeated 10 times (240 hour test). Within 2 hours after removal from the test
chamber, the generator shall be subjected to the dielectric strength test in 4.6.5.
4.6.15 Fungus. The components of one generator, including any required lubricants, shall be
subjected to a fungus resistance test for a minimum of 28 days and a maximum of 84 days
depending on the degree of certainty required in determining the existence or effect of fungal
growth. The generator shall be configured as it would be during shipping, storage, and service.
The test temperature shall be between 75° and 90°F with 95% ± 5% relative humidity. At least
five different species of fungus shall be used. Additional fungi may be used based on prior
knowledge of specific material deterioration characteristics. Any trace of fungus, degradation,
corrosion, or mechanical failure constitutes a cause for rejection.
4.6.16 Salt fog. The generator shall be subjected to a 50 hour salt fog test. The test shall be
conducted using steam or distilled, demineralized, or deionized water. The salt solution
concentration shall be 5 ± 1% at 95°F with a pH between 6.5 and 7.2. The salt solution shall
consist of sodium chloride (NaC1) containing by weight not more than 0.1% sodium iodide
(NaI) and not more than 0.5% total impurities. The test item shall be configured as it would be
during service. Any evidence of corrosion or corrosion-caused damage shall constitute a cause
for rejection. After the 50 hour test, the generator shall be subjected to the tests in 4.6.1, 4.6.2
and 4.6.5.
4.6.17 Explosive atmosphere. An explosive atmosphere test shall be conducted after vibration
and temperature testing. Ignition of test fuel vapor and air environment constitutes a cause for
rejection.
4.6.18 Cumulative voltage error. After completion of all the preceding tests, the voltage test in
4.6.4 shall be performed on all units undergoing first article inspection. Any voltage less than 19
shall be cause for rejection of the items.
8
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business