Underpressure Fault

TASK 47-11-00-810-812-A
Underpressure Fault

1. Possible Causes

IGGS ducts and connections
CSAS ducts and connections
IGGS filter element

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 21-58-00-710-002	Operational Test of the Conditioned Service Air System with Bleed Air
AMM 47-10-41-920-001	D-ULPA Filter Element Replacement
AMM 47-31-34-740-001	BITE Test of the IGGS with Bleed Air

3. Fault Confirmation
Subtask 47-11-00-740-068-A ** ON A/C NOT FOR ALL

A. Do the BITE test of the IGGS with bleed air AMM 47-31-34-740-001.

4. Fault Isolation
Subtask 47-11-00-810-061-A ** ON A/C NOT FOR ALL

A. Procedure

NOTE: Do the two subsequent steps at the same time. Two persons are necessary todo these steps.

(1) Do the BITE test of the IGGS with bleed air AMM 47-31-34-740-001.

WARNING: OBEY THESE INSTRUCTIONS WHEN YOU DO WORK ON THE IGGS:

WHEN YOU DO WORK ON THE DUAL FLAPPER CHECK VALVE, WEAR SAFETY BREATHING EQUIPMENT.
WHEN YOU DO WORK ON THE IGGS PALLET, WAIT 5 MINUTES BEFORE YOU GO INTO THIS WORK AREA AND LET AIR FLOW THROUGH IT. AIR FROM THE IGGS HAS A LOW OXYGEN CONTENT AND CAN CAUSE INJURY OR DEATH.

(2) Examine all the IGGS ducts and connections for signs of air leakage.
(3) If there are leaks, replace the defective ducts and/or connections of the IGGS.
(4) If there are no leaks:

NOTE: Do the two subsequent steps at the same time. Two persons are necessary to do these steps.

(a) Do the Operational Test of the CSAS with bleed air AMM 21-58-00-710-002.
(b) Examine all the CSAS ducts and connections for signs of air leakage.
(c) If there are leaks, replace the defective ducts and/or connections of the CSAS.
(d) If there are no leaks, replace the IGGS filter element AMM 47-10-41-920-001.

Subtask 47-11-00-740-069-A ** ON A/C NOT FOR ALL

B. Do the BITE test of the IGGS with bleed air AMM 47-31-34-740-001.

NOTE: After the subsequent flight make sure that the fault does not continue.

[Rev.8 from Aug 2018] 2026.04.04 04:34:23 UTC