Liquid Level Transmitter Failure

TASK 38-31-00-810-837-A
Liquid Level Transmitter Failure

1. Possible Causes

sense line
XMTR-LEVEL [40MG]
aircraft wiring
DEU-B [300RH8]
filter of the water separator
water separator

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 38-31-00-810-853-A	Wrong Message from LLT
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
ASM 383111
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 38-31-67-000-001	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 38-31-00-710-121-A ** ON A/C NOT FOR ALL

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

Subtask 38-31-00-740-072-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 38-31-00-810-139-A ** ON A/C NOT FOR ALL

A. If the LAST LEG Report gives the maintenance message
LIQD LVL XMTR (40MG)
OUTPUT VALUE AT FAILURE ENTRY (MILLIAMP)
and
the FAP BLUE CARD shows NO WASTE QUANTITY DATA AVAILABLE
or
VACUUM SYSTEM DISABLED - WASTE TANK FULL:

do the procedure in (Ref. TSM TASK 38-31-00-810-853).

NOTE: This is to make sure that the messages are not incorrect. An incorrect message can occur if there is a mismatch between the LLT and the CIDS system.

clean the sense 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:

do a check and repair the aircraft wiring , ASM 383111.

(3) If the fault continues:

replace the DEU-B [300RH8] .

(4) If the fault continues:

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

(5) 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 38-31-00-710-122-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