MIL-DTL-27723F
seconds. Power shall then be removed and the probe subjected to -70°C for an additional 24
hours. After exposure, the resistance of the temperature-sensing element shall be determined at
0°C and 100°C. The probe shall meet the low temperature and power consumption requirements
of 3.6.13. No damage shall result from the test.
4.6.14 High temperature exposure. The probe shall be subjected consecutively to a
temperature of 250±10°C for a period of 7 hours and a temperature of 350±10°C for a period of 1
hour for a total of 80 hours (10 cycles). The probe shall meet the high temperature exposure
requirements of 3.6.14.
4.6.15 Temperature calibration. The resistance of the temperature-sensing element shall
be measured at 0°C, at 100°C, at a temperature between 250°C and 350°C, and at -40°C. The
resistance at each of these points shall meet the temperature resistance requirements of 3.5.2.1.
4.6.16 Vibration. The probe shall be subjected to a vibration test in accordance with
MIL-STD-810 method 514.3 at room temperature with rated load applied. No visible damage to
the probe shall result. After vibration, the resistance of the temperature-sensing element shall be
determined at 0°C and at 100°C and shall not differ by more than the equivalent 0.2°C from the
resistance values before vibration testing. The probe shall meet the vibration requirements of
3.6.
4.6.17 Heater power consumption. The deicing heater element shall be energized at
rated voltage with the housing submerged in agitated ice water (as an approximation to icing
conditions). The power consumption shall meet the requirements of 3.8.1.
4.6.18 Hermetic sealing. The probe shall be subjected to an immersion test in
accordance with method 512 of MIL-STD-810, using water as the immersion fluid. The probe
shall meet the sealing requirements of 3.5.2.2.
4.6.19 Recovery error. The recovery error of the temperature-sensing element shall be
determined at the sea level pressure and temperature and shall not exceed 0.005.
The recovery error can be defined by the following equation:
Where: T0 = true stagnation temperature in degrees Kelvin
TP = temperature of the probe in degrees Kelvin
N = recovery error
4.6.20 Self-heating. The probe shall be tested in air at room temperature and pressure in
an internal air flow of mach 0.3 for the self-heating effect of the temperature-sensing element.
Sufficient voltage shall be applied to produce a current of 50 ma through the temperature-sensing
element and the element shall meet the requirements of 3.6.4.
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