RIBBON HEATERS - REMOVAL/INSTALLATION
1. General
A. Ribbon heater tapes are used to prevent ice formation on some potable water supply lines and drain lines. The heaters are wrapped around and secured to the lines with flame-resistant adhesive tape.
2. Equipment and Materials
A. Flame-resistant adhesive tape (Ref 20-30-51)
3. Remove Ribbon Heater
A. Open DRAIN HEATERS circuit breakers on applicable circuit breaker panel.
B. Gain access to defective heater.
C. Cut heater electrical leads.
NOTE: Leave cut electrical leads in place as guide in locating splice. Remove when splicing new leads.
D. Remove adhesive tape from heater and remove heater from line.
NOTE: Observe adhesive tape locations and record. Apply adhesive tape to new heater at some locations as old heater.
4. Install Ribbon Heater
A. Position heater on water line and secure with flame-resistant adhesive tape in same locations as old heater.
WARNING: DO NOT OVERLAP RIBBON HEATERS. DO NOT INSTALL CLAMPS OVER RIBBON HEATERS. DO NOT INSTALL INSULATION BLANKETS OVER RIBBON HEATERS. PROVIDE 1.0-INCH MINIMUM CLEARANCE BETWEEN RIBBON HEATERS AND INSULATION. RESTAIN RIBBON HEATERS WITH FLAME-RESISTANT TAPE. RESTRAIN ELECTRICAL LEADS WITH STRAP. INCORRECT INSTALLATION OF RIBBON HEATERS CAN RESULT IN EXCESSIVE HEAT BUILDUP AND DAMAGE TO HEATER.
NOTE: Excess heater length may be absorbed by increasing turns or wraps as long as heaters do not overlap.
B. Locate splice area and splice electrical leads.
C. Test heater.
(1)
Close DRAIN HEATERS circuit breakers on applicable circuit breaker panel.
(2)
Provide electrical power.
(3)
Confirm that heater warms up.
NOTE: Heaters will not warm up if ambient or water line temperature at thermostat is above approximately 45°F (7.2°C).
(4)
Remove electrical power if no longer required.
D. Reinstall panels or close access doors as applicable.
Feb 20/86 30-71-11 Page 401 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
DRAIN PIPE HEATING GASKET - REMOVAL INSTALLATION
1. General
A. The forward and the aft drain pipe heater gaskets heat the forward, mid and aft drain pipes to prevent ice formation. The gaskets are positioned around the drain pipe under the drain cap. The toilet waste tank drain duct nipple (drain cap) must be removed to remove the heating gasket.
2. Materials
A. Sealant, Chromate Type - BMS 5-95 (Ref 20-30-11)
B. Solvent - Spec TT-M-261 or JIS-K-8903 Methyl-ethyl-ketone (Ref 20-30-31)
C. Cheesecloth - Commercial
D. Tape - Teflon, Permacel P-424 (Ref 20-30-51)
3. Remove Drain Pipe Heating Gasket (Fig 401)
A. Service waste tank (Ref 12-17-0).
NOTE: Do not add flushing compound until drain pipe heating gasket is installed.
B. Open the following applicable circuit breaker on the P18 load control center and attach DO-NOT-CLOSE identifier:
(1) DRAIN HEATER
C. For forward service panel, remove aft access door on right inner wall of nose wheel well to access clamp securing drain duct to nipple.
D. For aft service panel, remove aft cargo compartment aft bulkhead lining panel.
E. Remove clamp securing waste drain duct to drain nipple.
F. Pull down on waste drain cap handle and open cap.
G. Remove mounting bolts from drain nipple (8 places).
(1)
Remove seven bolts leaving one bolt attached loosely.
(2)
Hold onto nut ring from behind service panel to prevent its loss.
(3)
Remove remaining bolt and nut ring.
H. Remove drain nipple from service panel using care to not damage heater gasket.
I. Cut lead wires close to heating gasket.
NOTE: Lead wires may be left in place to aid in locating the splice. These wires must be removed before installing the new heating gasket.
500
Feb 20/89 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 30-71-21 Page 401
Drain Pipe Heating Gasket Installation 500
30-71-21 Figure 401 Feb 20/89
Page 402
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
J. Remove heating gasket.
4. Install Drain Pipe Heating Gasket (Fig. 401)
A. Clean mounting surfaces and bolts with solvent. Remove old sealant from bolts.
B. Remove old heater leads and splice in new heater leads.
C. Position heating gasket, checking that no portion of the wires remain outside.
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