Failure of the Yellow Hydraulic Pressure Switch

TASK 27-92-00-810-828-A
Failure of the Yellow Hydraulic Pressure Switch

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 31-32-00-810-932-A	Failure of the Discrete Links
ASM 279227
AMM 27-93-34-000-001	Removal of the ELAC
AMM 27-93-34-400-001	Installation of the ELAC
AMM 27-94-34-000-001	Removal of the SEC
AMM 27-94-34-400-001	Installation of the SEC
AMM 27-96-00-740-001	BITE Test of the EFCS (Ground Scanning)
AMM 29-10-00-863-002	Pressurize the Yellow Hydraulic System with a Hydraulic Ground Power-Cart
AMM 29-10-00-864-002	Depressurize the Yellow Hydraulic System
AMM 29-32-12-000-003	Removal of the System Pressure Switch
AMM 29-32-12-400-003	Installation of the System Pressure Switch

3. Fault Confirmation
Subtask 27-92-00-860-064-A

A. Job Set-Up
(1) Pressurize the Yellow hydraulic system AMM 29-10-00-863-002.

Subtask 27-92-00-865-059-A

B. Table of the circuit breakers used in this procedure:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	FLIGHT CONTROLS/FCDC1/SPLY	20CE1	B10
121VU	FLIGHT CONTROLS/FCDC2/SPLY	20CE2	Q20

Subtask 27-92-00-740-100-A

C. Test
(1) Do the BITE test of the EFCS (Ground Scanning) AMM 27-96-00-740-001.

4. Fault Isolation
Subtask 27-92-00-810-077-A

A. If the BITE test gives the maintenance message:
Y HYD PRESS SW2

do the trouble shooting procedure (Ref. TSM TASK 31-32-00-810-932)
. related to the DSI 19 discrete input signal of the SEC 2 and SEC 3,
. related to the DSI 32 discrete input signal of the ELAC 1 MON and ELAC 2 MON ASM 279227.
open and close the circuit breakers 20CE1 and 20CE2.

If you do not find faults during the trouble shooting procedure (Ref. TSM TASK 31-32-00-810-932), go to Para. (5).
(1) If the fault continues:

(2) If the fault continues:

(3) If the fault continues:

(4) If the fault continues:

(5) If the fault continues:

replace the SYSTEM-PRESS-SW [3151GN] AMM 29-32-12-000-003 and AMM 29-32-12-400-003.
open and close the circuit breakers 20CE1 and 20CE2.

(a) If the fault continues:

do a check and repair the wiring from the pressure switch (3151GN) pins A/A and A/B to the ground, SEC2, SEC3, ELAC1 and ELAC2 ASM 279227.
open and close the circuit breakers 20CE1 and 20CE2.

Subtask 27-92-00-740-101-A

B. Do the BITE test given in Para. 3.

5. Close-up
Subtask 27-92-00-860-065-A

A. Depressurize the Yellow hydraulic system AMM 29-10-00-864-002.

[Rev.8 from Aug 2018] 2026.04.04 04:39:23 UTC