B3-008140 - NO RESPONSE TO CMD [CARGO SMOKE DET]

02/26/21

Message Overview:

Message Name:

NO RESPONSE TO CMD

Message Code:

B3-008140

Associated CAS:

Reporting LRU:	CARGO SMOKE DET
System Description:	26-15-00
Schematic Diagram:	26-15-00
Wiring Diagram:	26-11-05 26-15-05

Message Description:

Cargo smoke detector has failed to respond command, test command wire open, FIREX CTRL Unit input monitoring circuit has failed or power input to smoke detector failed.

Possible Causes:

Smoke Detector (A92)
Fire-Detection-And-Extinguishing (FIREX) Control Unit (A91)
Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

The detector will provide an alarm signal to the Control Unit whenever a 4% smoke concentration is detected in the cargo bay.

Quick Links:

Removal of the Fire-Detection-and-Extinguishing (FIREX) Control-Unit	AMM 26-11-01-000-801
Installation of the Fire-Detection-and-Extinguishing (FIREX) Control-Unit	AMM 26-11-01-400-801
Removal of the Baggage-Compartment Smoke Detector	AMM 26-15-05-000-801
Installation of the Baggage-Compartment Smoke Detector	AMM 26-15-05-400-801
Restoration (Cleaning) of the Baggage Compartment Smoke Detector (P/N 473597-2)	AMM 26-15-05-615-801
Smoke Detector Assembly	CMM 26-10-69
Electrical Bonding - Adjustment/Test	SPM 51-80-00-05
Wiring - Maintenance Practices - ALL	SPM 20-12-00-02
Wire Repair - Maintenance Practices - ALL	SPM 20-12-10-02

Troubleshooting Recommendations:

Perform the following steps if the CARGO SMOKE CAS messages has illuminated without actual smoke in the cargo area.

Check for unwanted debris inside the smoke detector
Check the FIREX Control Unit (A91) circuit breaker CB2-A11, pull and reset.
1. If system checks are good, do close out.
2. If fault remains, continue with next step.
Verify 28 VDC input to the smoke detector unit at A92P1 pins B and E.
1. If 28 VDC is NOT present, go to step 5.
2. If 28 VDC is present, continue with next step.
Replace FIREX CU.
1. If system checks are good, do close out.
2. If fault remains, continue with next step.
Do wiring checks between FIREX CU (A91P2 pin 1) and the smoke detector (A92P1 pin B). Repair wiring as required.
1. If system checks are good, do close out.
2. If fault remains, continue with next step.
Do wiring checks between the smoke detector (A92P1 pin E) and ground. Repair wiring as required.
1. If system checks are good, do close out.
2. If fault remains, continue with next step.
Do wiring checks between FIREX CU (A91P2 pins 55 & 47) and the smoke detector (A92P1 pins C&D). Repair wiring as required.
1. If system checks are good, do close out.
2. If fault remains, continue with next step.
Replace Baggage Compartment Smoke Detector.
Do close out.