Failure of the Blue Hydraulic Pressure Switch

TASK 27-92-00-810-821-B
Failure of the Blue 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 29-10-00-863-003	Pressurize the Blue Hydraulic System with a Hydraulic Ground Power-Cart
AMM 29-10-00-864-003	Depressurize the Blue Hydraulic System
AMM 29-32-12-000-002	Removal of the System Pressure Switch
AMM 29-32-12-400-002	Installation of the System Pressure Switch

3. Fault Confirmation
Subtask 27-92-00-860-068-A

A. Job Set-Up
(1) Pressurize the Blue hydraulic system with the electric pump AMM 29-10-00-863-003.

Subtask 27-92-00-865-051-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 27-92-00-740-104-A

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

4. Fault Isolation
Subtask 27-92-00-810-079-A

A. If the BITE test gives the maintenance message:
B HYD PRESS SW1

do the trouble shooting procedure (Ref. TSM TASK 31-32-00-810-932)
. related to the DSI 18 discrete input signal of the SEC 1,
. related to the DSI 40 discrete input signal of the ELAC 1 COM and ELAC 2 COM 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. (4).
(1) If the fault continues:

(2) If the fault continues:

(3) If the fault continues:

(4) If the fault continues:

replace the SYSTEM-PRESS-SW [2151GN] AMM 29-32-12-000-002 and AMM 29-32-12-400-002.
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 (2151GN) pins A/A and A/B to the ground, SEC1, ELAC1 and ELAC2 ASM 279227.
open and close the circuit breakers 20CE1 and 20CE2.

Subtask 27-92-00-740-105-A

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

5. Close-up
Subtask 27-92-00-860-069-A

A. Depressurize the Blue hydraulic system AMM 29-10-00-864-003.

[Rev.8 from Aug 2018] 2026.04.04 04:39:22 UTC