Aircraft technical Basics: TM 1-413, Aircraft Instruments, 1942: 7. De-Icing Pressure Gages
TM 1-413, TECHNICAL MANUAL, AIRCRAFT INSTRUMENTS, Prepared under direction of the Chief of the Air Corps, WAR DEPARTMENT, WASHINGTON February 2, 1942. (This manual supersedes TM 1-413, November 7, 1940)
SECTION VII - DE-ICING PRESSURE GAGES
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Paragraph |
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Purpose and use |
26 |
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Description |
27 |
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Operation |
28 |
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Installation |
29 |
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Maintenance |
30 |
26. Purpose and use.-a. The de-icing system pressure gage measures and indicates the differential air pressure in the airplane de-icing system when this system is in operation.
b. The specific uses are to
(1) Show if there is sufficient pressure to operate the rubber expansion cells on the wings and stabilizers of the airplane.
(2) Provide a means of measurement when setting the relief valve and regulator in the de-icing pressure system.
27. Description. -a. The de-icing system pressure gage (fig. 11) consists of a bakelite case containing a Bourdon tube and a sector gear with pinion for amplifying the motion of the tube and transferring it to the pointer. A vent at the bottom of the case keeps the inside at atmospheric pressure and also provides a drain for any accumulated moisture. The system pressure enters the Bourdon tube through a connection at the back of the case.
b. The range of the scale is from 0 to 20 pounds per square inch with graduations in increments of 2 pounds per square inch. The pointer, numerals, and main graduations are painted with luminous material. Individual lighting is provided by a small lamp inserted in the corner of the case.
28. Operation.-When installed on the airplane and connected into the de-icing pressure system, the gage reading will remain zero at all times except when the de-icing system is operating. Due to periodic inflation and deflation of the cells, the pointer of the gage will fluctuate from approximately 0 to 8 pounds per square inch. This is a normal fluctuation and should not be confused with pointer oscillation which is not a normal condition in any airplane gage and which, if present, must be corrected.
29. Installation.-See section III.
30. Maintenance. See section II.
FIGURE 11.- De-icing pressure gage
