MIL-DTL-5790H
4.6.20 Shock. The transmitter shall be subjected to a shock of 20g for 11 milliseconds
while electrically connected to the MIL-I-7087 indicator with power applied. The transmitter shall
be subjected to the scale error and friction error tests. The tolerances shall not exceed those
specified in tables I and II.
4.6.21 Humidity. The transmitter shall be subjected to the humidity test in accordance
with category B of RTCA DO-160 while electrically connected to the MIL-I-7087 indicator with
power applied. Immediately upon completion of the test, the transmitter shall be externally dried
and subjected to scale error, friction error, and dielectric strength. The tolerances shall not exceed
those specified in section 3.
4.6.22 Fungus. The transmitter shall be subjected to the fungus test in RTCA DO-160.
4.6.23 Reliability test plan and report. Prior to starting the reliability test, the manufacturer
shall submit a detailed reliability test plan for formal approval by the procuring activity. The
manufacturer may refer to the requirements specified in Test Plan I-D of MIL-HDBK-781 as a guide
for the reliability test plan. The manufacturer shall prepare a final report that summarizes the
achieved reliability of the test samples. The report shall also contain test procedures, details of any
malfunctions, and applicable charts and graphs showing failures/MTBF plotted against test time and
other pertinent test data. The manufacturer may refer to the guidelines outlined in MIL-HDBK-831
for preparing the report.
4.6.23.1 Reliability test. The seven transmitters shall each accumulate 2,000 hours of test
time by being subjected to a series of environmental test cycles. The transmitters shall be checked
every 25 test cycles (250 hours) for scale error. The scale error shall not exceed 150 percent of the
room temperature tolerances specified in table I. Each test cycle is approximately 10 hours in
duration and shall meet the following requirements:
a. The test cycle shall begin when rated power (26 ± 2 Vac at 400 ± 5 Hz) is applied to the
transmitter and the temperature is at -67 °F. The temperature shall be cycled as follows: 4 hours at -67 °F,
increase temperature to 250 °F at a rate of 9 °F per minute; 4 hours at 250 °F, lower temperature to -67 °F
at a rate of 9 °F per minute, and repeat cycle. Prior to the temperature changing from low to high and high
to low the power shall be turned off for a period of 10 minutes during each 10-hour cycle.
b. Oil pressure shall be applied to the transmitter at a rate of 3 to 4 cpm from 0 to
85 ± 5 percent of full scale and return to 0 for the duration of the 2,000 hours of testing.
c. The transmitter shall be vibrated in accordance with 4.6.9 for 10 minutes out of every
hour of power "ON" time.
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