L22861
541 Main Cargo Door Heating Blanket Control Circuit
Feb 01/74 Figure 1 21-41-0
Page 1
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
Main Cargo Door Heating Blankets 506
21-41-0 Figure 2 Nov 15/68
Page 2
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
MAIN CARGO DOOR HEATING BLANKET - REMOVAL/INSTALLATION
EFFECTIVITY
Passenger/Cargo Convertible Airplanes
1. Remove Main Cargo Door Heating Blanket
A. Open MAIN CARGO DOOR HEATER circuit breaker on 115 volt ac bus No. 2 circuit breaker panel P6.
B. Remove main cargo door lining. (See Main Cargo Door Lining - Removal/Installation, Chapter 52.)
C. Remove fasteners that attach heating blanket to door frame. (See figure 401.)
D. Remove two fiberglass insulation panels from the lower aft portion of the door. (See Main Cargo Door Insulation - Removal/Installation, Chapter 52.)
E. Disconnect and mark electrical wires in main cargo door heater terminal strip located on the aft portion of stringer No. 14 of the cargo door.
F. Disengage electrical wire fasteners and pull wires through holes on door frame.
3. Install Main Cargo Door Heating Blanket
A. Insert electrical wires into holes on door frame and engage wire fasteners.
B. Connect electrical wires in main cargo door heater terminal strip.
C. Perform functional test of heating blankets as described in Main Cargo Door Heating Blanket -Adjustment/Test.
D. Install the two fiberglass insulation panels that were removed to facilitate door heating blanket removal. (See Main Cargo Door Insulation - Removal/Installation, Chapter 52.)
E. Position heating blanket in place and install fasteners that attach heating blankets to door frame.
Nov 15/68 21-41-11 Page 401
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
Main Cargo Door Heating Blanket Installation 506
21-41-11 Figure 401 Nov 15/68
Page 402
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
MAIN CARGO DOOR HEATING BLANKET - ADJUSTMENT/TEST
EFFECTIVITY
Passenger/Cargo Convertible Airplanes
1. Functional Test of Main Cargo Door Heating Blankets
A. Equipment and Materials
(1)
Electrical ground power supply, 115/200 volts ac, 400 cps, 3 phase
(2)
Volt-Ohm-Milliameter, Triplet 625NA or equivalent
(3)
Multimeter, Simpson 260 or equivalent
B. Test Main Cargo Door Heating Blankets
(1)
Provide electrical power.
(2)
Open MAIN CARGO DOOR HTR circuit breaker on panel P6.
(3)
Check that CARGO DOOR HEAT switch on aft attendant's panel (P14) is OFF.
(4)
Disconnect wire from terminal No. 8 of terminal strip T259 above cargo door.
(5)
Measure resistance of heating blankets by connecting ohmmeter from wire disconnected in step B.(4) and to ground. Check that the resistance for the blankets is between 45 and 65 ohms.
NOTE: To check resistance of individual heating blankets, disconnect ground wire for heating blanket being checked from main cargo door heater terminal strip located on the aft portion of stringer No. 14 of the cargo door. Measure resistance between terminal 1 on main cargo door heater terminal strip and terminal 2 (ground wire removed from terminal strip) for heating blanket being checked. Check that resistance for the upper heating blanket measures 128 to 157 ohms or that of the lower heating blankets measures as follows: 163 to 200 ohms for a blanket with dimensions of 166 x 17.5 inches, 286 to 349 ohms for a blanket with dimensions of 167.4 x 10 inches.
May 15/79 21-41-11 Page 501
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
(6)
Reconnect the wire to terminal No. 8 of terminal strip T259.
(7)
Close MAIN CARGO DOOR HTR circuit breakers on panel P6.
(8)
Place CARGO DOOR HEAT switch to ON.
(9)
Measure voltage between terminal No. 8 of terminal strip T259 and ground. Check that voltage is 115 +3 volts ac.
(10)
By hand, feel that heating blankets commence heating with power applied.
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