Liquid Level Transmitter and Liquid Level Sensor failure

TASK 38-31-00-810-844-A
Liquid Level Transmitter and Liquid Level Sensor failure

1. Possible Causes

LLT reference line
XMTR-LEVEL [40MG]
SENSOR,LEVEL [41MG]
DECODER/ENCODER UNIT B [300RH7]
DEU-B [300RH8]
filter of the water separator
water separator

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 23-73-47-000-001	Removal of the Decoder/Encoder Unit B (300RH)
AMM 23-73-47-400-001	Installation of the Decoder/Encoder Unit B (300RH)
AMM 38-31-00-100-009	Cleaning of the Liquid Level Transmitter (LLT) Reference Line
AMM 38-31-00-710-009	Operational Test of the Toilet Unit
AMM 38-31-00-740-001	BITE Test of the Vacuum Toilet System
AMM 38-31-62-000-001	Removal of the Liquid Level Transmitter
AMM 38-31-62-400-001	Installation of the Liquid Level Transmitter
AMM 38-31-63-000-001	Removal of the Liquid Level Sensor
AMM 38-31-63-400-001	Installation of the Liquid Level Sensor
AMM 38-31-67-000-001	Removal of the Water Separator
AMM 38-31-67-400-001	Installation of the Water Separator
AMM 38-31-67-610-001	Inspect Water Separator and Associated Filter Element, and Clean as Necessary
MCDU Display

3. Fault Confirmation
Subtask 38-31-00-710-135-A ** ON A/C NOT FOR ALL

A. Do a test of the vacuum toilet system AMM 38-31-00-710-009.

Subtask 38-31-00-740-079-A ** ON A/C NOT FOR ALL

B. Do the procedure to get access to the CFDS SYSTEM REPORT/TEST menu PAGE AMM 38-31-00-740-001.

4. Fault Isolation
Subtask 38-31-00-810-146-A ** ON A/C NOT FOR ALL

A. If the LAST/PREVIOUS LEGS Report gives the maintenance message
LIQD LVL XMTR (40MG) and LIQD LVL SNSR (41MG)
LIQD LVL XMTR OUTPUT VALUE AT FAILURE ENTRY (MILLIAMP),
LIQD LVL SNSR OUTPUT VALUE AT FAILURE ENTRY (VOLT)
and
the FAP give the messages VACUUM SYSTEM DISABLE - WASTE TANK FULL
NO WASTE QUANTITY DATA AVAILABE:

clean the LLT reference line , AMM 38-31-00-100-009.

(1) If the fault continues:

replace the XMTR-LEVEL [40MG] , AMM 38-31-62-000-001 and AMM 38-31-62-400-001.

(2) If the fault continues:

Replace the SENSOR,LEVEL [41MG] , AMM 38-31-63-000-001 and AMM 38-31-63-400-001.

(3) If the fault continues:

replace the DECODER/ENCODER UNIT B [300RH7] , AMM 23-73-47-000-001 and AMM 23-73-47-400-001.

(4) If the fault continues:

replace the DEU-B [300RH8] , AMM 23-73-47-000-001 and AMM 23-73-47-400-001.

(5) If the fault continues:

do a check of the overboard vent lines,
if necessary, clean the overboard vent lines.

(6) If the fault continues:

do an inspection of the filter of the water separator ,
if necessary, clean the filter of the water separator AMM 38-31-67-610-001,
if necessary, do a check and replacement of the water separator AMM 38-31-67-000-001 and AMM 38-31-67-400-001.

Subtask 38-31-00-710-136-A ** ON A/C NOT FOR ALL

B. Test
(1) Do the test as given in paragraph 3. A. to check the correct operation.
(2) After the subsequent flight, make sure that the fault does not continue.

[Rev.8 from Aug 2018] 2026.04.04 04:34:15 UTC