500 500 Window No. 5 Thermal Switch Installation
May 15/67 Figure 401 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 30-41-31 Page 401
C. Conductive Compound (Use only one of the compounds listed below):
(1)
A00062 Compound, Thermal Heat Sink - DC340
(2)
A00214 Compound, Potting - BMS 5-28, Type 3
(3)
A00323 Adhesive - BAC 501, Type 54
3. Remove Window Heat Thermal Switch
A. Open respective WINDOW ANTI-ICE No. 4 and 5 circuit breaker on circuit breaker panel P6-11 or P6-12.
B. Disconnect electrical leads from switch.
C. Remove switch by pulling back rat-trap spring, which holds switch against window.
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4. Install Window Heat Thermal Switch
NOTE: If new window pane has been fitted, thermal switch must be installed as closely as possible to arrow on window's lower edge, because this mark indicates best switch location for that individual window. To achieve this it may be necessary to install rattrap spring bracket on different pair of window frame bolts from those originally used. Elongated holes in bracket provide further adjustment. Trim royalite cover as required to accommodate new switch location.
A. Thoroughly clean face of switch and surface of window with solvent, BMS 3-2, Type I. Wipe off surplus solvent and allow both surfaces to dry.
B. Thermal switch must be installed with conductive compound as follows:
(1) If you use the two part or four part compounds, do these steps:
(a) Mix the compounds as instructed:
1) If you use Marco conductive compound (four part), prepare compound by thoroughly mixing ingredients in following order and proportions (by weight): Resin (100 parts), Aluminum powder (70 parts), Accelerator (2 parts), Catalyst (2 parts).
NOTE: At temperatures between 70°F and 90°F, compound must be used within approximately 30 minutes of mixing. Approximately 43.5 grams of the mixture should be sufficient to install switch on both No. 5 windows.
2) If you use two part compounds, mix and use in accordance with manufacturer’s instructions.
(b)
Apply CD-2 Mold Release B-2, or Permacel 422 Teflon Tape, to the switch surface facing the window.
(c)
Apply compound over mold release or tape on face of switch to be in contact with window. Compound should be slightly thicker at center of face than around its rim.
(2)
If you use DC-340 apply coating of heat sink compound to face of thermal switch.
CAUTION: EXCESS THICKNESS OF COMPOUND WILL AFFECT ITS THERMAL LAG, THEREFORE, AMOUNT USED SHOULD BE HELD TO THE MINIMUM REQUIRED FOR FILLING THE GAP.
(3)
Pull rattrap spring back and engage with locating slot across back of switch, whose terminal lugs should point toward spring hinge.
(4)
Allow spring to press switch against window and wipe off surplus compound, which exudes from joint.
(5)
Observe bond from outside window and check that no air bubbles larger than 3/32 inch in diameter are visible in compound and that total area of smaller bubbles does not exceed 10 percent of bonded area. If these requirements are not fulfilled, heat conductivity will be impaired and bond must be dissolved and made again.
(6)
If you used the two part or four part compounds, wait at least one hour for compound to cure. At temperatures below 50°F a longer time will be required. Curing can be regarded as complete when compound has become hard and brittle.
(7)
When compound is completely cured, use solvent to wipe off excess compound still remaining on window. Remove teflon tape from microswitch if used in step (2).
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CAUTION: TEFLON TAPE MUST BE REMOVED FROM FACE OF THERMAL SWITCH BEFORE TURNING ON WINDOW HEAT. THE TAPE ACTS AS AN INSULATOR AND WILL PREVENT SWITCH FROM PROTECTING WINDOW AGAINST OVERHEAT.
C. Connect electrical leads to switch terminal lugs.
D. Close circuit breaker opened in step 3.A.
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WINDSHIELD WIPER SYSTEM - DESCRIPTION AND OPERATION
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