Buck 1011C, Руководство по эксплуатации

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above 0
°
C, causing the deposit to melt. Prevent this by again switching to MAX COOL to
hold mirror below 0
°
C. This will insure that final reading will be in terms of frost point.
4.2.4 Low Frost Points
At very low frost points, it is good practice to allow the instrument to operate
continuously, to assure operation in the ice phase.
Performing a rebalance is not recommended, as it could take hours for the frost layer to
reform. If a balance check is done or the mirror is otherwise cleared of its frost layer, take
a reading just before clearing; allow sufficient time to reform a stable ice layer afterwards.
The MAX COOL switch allows the operator to determine whether there is adequate
cooling when the system is operating at very low frost points. Momentarily switch to
MAX COOL and observe the dew/frost point display. If the indicated temperature drops,
there is reserve cooling capability.
4.2.5 Pressure Effects
The 1011C system will display the Dew/Frost Point at the pressure that the sensor chamber
is exposed to. The location of the sensor probe on the aircraft can influence the pressure.
Attaching an altimeter and comparing it with the aircraft altimeter is a convenient way of
accomplishing this.
The dew point temperature is a function of the sample gas pressure. If the pressure of the
gas is increased or reduced from atmospheric pressure, the dew point is correspondingly
increased or decreased. It is general practice to assume, unless stated otherwise, that dew
point is with respect to atmospheric pressure. To calculate dew point error due to pressure
change, refer to Appendix 1.
4.2.6 Typical Response to Humidity Changes
In level flight the system should track the Dew/Frost Points very well. Typical responses
to step changes are shown in Figure 9. However, be cautious about readings under the
following conditions:
Icing conditions
Sudden transition from low to high dew points
Particularly with rise in ambient temperature
(typical on descent into warm moist air)
Under normal conditions, the 1011C will handle the transition without problem, but under
severe transitions the sensing cavity may collect excessive water. Refer to next section.
4.2.7 Mirror Flooding