E. The lower nose compartment access door and the electronic equipment compartment external access door share the same door warning light (Fig. 2). A microswitch is located at each compartment access door and the unlatching of a door will energize the circuit to the warning light. Similarly, the tire burst protector screen doors (if installed) share the same door warning light. The unlatching of either door will activate the proximity sensor at the door and energize the circuit to the tire screen door warning light.
2. Operation
A. The door warning system circuits are powered from a 28-volt dc door warning circuit breaker and the activation of any one of the switches or sensors in the system provides a path to ground through the appropriate warning light which is thus illuminated. The pair of bulbs comprising each warning light are connected in parallel with each other and the circuit is arranged to ensure that the activation of one switch or sensor energizes only the proper warning light.
B. The lights can be tested individually or the master test switch can be used at any time to connect all the pairs of lights to ground, thus energizing the lights and proving that they are operative.
C. The switches and sensors installed at the doors are arranged so that the circuits to the individual door warning lights are de-energized when the doors are closed and the latch fittings are completely engaged. When a door is unlatched, the switch or sensor at the door completes the circuit to the appropriate door warning light which is illuminated, thus warning that the door is unlatched.
D. When the forward entry door is opened or the airstair exterior control handle is pulled to extend airstair, the airstair door lockpin is retracted, causing the airstair door warning sensor to actuate, illuminating the airstair warning light. When airstair door closes, warning light will be extinguished by retraction of the airstair door lockpin which deactivates the lockpin sensor when sensor actuator on lockpin comes into proximity to sensor.
E. With the illumination of an individual system indicator light, both MASTER CAUTION lights and the DOOR master caution annunciator light illuminate to indicate a system malfunction. The MASTER CAUTION lights on the lightshield indicate a malfunction has occurred, the DOOR master caution annunciator light indicates the affected system. The individual door warning system indicator light indicates what portion of the system is malfunctioning. Both MASTER CAUTION lights and the DOOR master caution annunciator may be extinguished by pressing either MASTER CAUTION light, which interrupts power to the lights and resets the system to allow another malfunction to be indicated by the MASTER CAUTION and master caution annunciator lights. The individual door warning system indicator light will remain on until the malfunction is corrected.
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5C1 Door Warning System Switch and Sensor Location
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Door Warning System Circuit 5C1
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F. To recall an uncorrected malfunction, press either master caution annunciator on the light shield. While the annunciator is held depressed, both MASTER CAUTION and all master caution annunciators will be illuminated. When released, only the MASTER CAUTION lights and the appropriate master caution annunciator will remain on. When the malfunction is corrected, all master caution, system annunciator and individual system indicator lights will go out.
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DOOR WARNING SYSTEM - TROUBLE SHOOTING
1. General
A. The door warning system troubles will be indicated by faulty indications on the Door Warning Module and/or Master Caution Annunciator. The various combinations of faulty indications that can be caused by a fault in the door warning circuits are listed in the following trouble shooting chart.
B. Since the circuits controlling the various lamps on the door warning module are all similar in operation, a specific light malfunction is referred to as a Door Warning light in the fault column of the chart. An incorrect indication of the MASTER CAUTION or DOORS lights on the Master Caution Annunciator is referred to as a Master Caution light in the chart. Therefore when performing an isolation procedure for a specific light fault, refer to the table for the specific light and its corresponding circuit isolation points referred to in the isolation procedure.
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