Installation of the Hydraulic Control Unit Pressure Switch [CFMI]

TASK 78-31-16-400-040-A
Installation of the Hydraulic Control Unit Pressure Switch

WARNING: BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER'S INSTRUCTIONS AND YOUR LOCAL REGULATIONS.

FIN: 4102KS ** ON A/C NOT FOR ALL

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	ACCESS PLATFORM 1M(3 FT)
No specific	AR	PLIERS - NOSE, SOFT, LONG
No specific	AR	WARNING NOTICE(S)
No specific	Torque wrench: range to between 17 and 13 lbf.in (0.19 and 0.15 m.daN )

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.CP1039)	acetone
(Material No.CP1041)	isopropyl alcohol
(Material No.CP2011)	stoddard solvent
(Material No.CP2245)	finish paint EA4 blue 5991
(Material No.CP2428)	PR 1422A
(Material No.CP2559)	ardrox 552
(Material No.CP2560)	turco ind 79
(Material No.CP2566)	mag-chem teksol
(Material No.CP2584)	degreasol 99 R
(Material No.CP2656)	mag-chem skysol
(Material No.CP8001)	lockwire 0.032 in. (0.8 mm) dia.
(Material No.CP8002)	lockwire 0.032 in. (0.8 mm) dia
(Material No.06LCG9)	Non Hardening Jointing Putty-Medium Temp. Area - -

C. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
FOR [1000EM1] (ENGINE-1)
437AL, 438AR
FOR [1000EM2] (ENGINE-2)
447AL, 448AR

D. Expendable Parts

FIG.ITEM	DESIGNATION	IPC-CSN
20	BACKUP RING	AIPC 78-31-16-01-030
10	PREFORMED PACKING	AIPC 78-31-16-01-040

E. Referenced Information

REFERENCE	DESIGNATION
TASK 29-14-00-614-002-A	Pressurization of the Hydraulic Reservoirs through the Ground Connector
TASK 29-14-00-614-002-A-01	Pressurization of the Hydraulic Reservoirs with the Auxiliary Power Unit (APU)
TASK 71-13-00-010-040-A	Opening of the Fan Cowl Doors
TASK 71-13-00-410-040-A	Closing of the Fan Cowl Doors
TASK 78-30-00-081-041-A	Make the Thrust Reverser Serviceable after Maintenance
TASK 78-30-00-481-041-A	Make the Thrust Reverser Unserviceable for Maintenance
TASK 78-30-00-710-040-A	Thrust Reverser Hydraulic System Bleed Procedure
Pressure Switch

3. Job Set-up
Subtask 78-31-16-860-051-A ** ON A/C NOT FOR ALL

A. Aircraft Maintenance Configuration
(1) On the center pedestal, on the ENG panel 115VU, make sure that a WARNING NOTICE(S) is in position to tell persons not to start the engine.
(2) On the overhead maintenance panel 50VU, make sure that the ON legend of the ENG/FADEC GND PWR/1(2) pushbutton switch is off. Make sure that a WARNING NOTICE(S) is in position to tell persons not to energize the FADEC 1(2).
(3) Make sure that the ACCESS PLATFORM 1M(3 FT) is in position.

Subtask 78-31-16-010-057-A ** ON A/C NOT FOR ALL

B. Get Access
(1) Make sure that the fan cowl doors are open: (Ref. AMM TASK 71-13-00-010-040)
(a) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(b) FOR [1000EM2] (ENGINE-2)
447AL 448AR

Subtask 78-31-16-040-055-A ** ON A/C NOT FOR ALL

C. Make sure that the thrust reverser is unserviceable (Ref. AMM TASK 78-30-00-481-041).

4. Procedure
Subtask 78-31-16-420-051-A ** ON A/C NOT FOR ALL

A. Installation of the pressure switch.

NOTE: You should apply a witness line of finish paint EA4 blue 5991 (Material No.CP2245) on all nuts and connections when you have checked their torques.

(1) Remove the pressure switch from the storage bracket.
(2) Remove the blanking plugs.
(3) Clean and dry the pressure switch :

WARNING: BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER'S INSTRUCTIONS AND YOUR LOCAL REGULATIONS.

(a) Clean and dry the pressure switch with acetone (Material No.CP1039) or stoddard solvent (Material No.CP2011) or ardrox 552 (Material No.CP2559) or turco ind 79 (Material No.CP2560) or mag-chem teksol (Material No.CP2566) or degreasol 99 R (Material No.CP2584) or mag-chem skysol (Material No.CP2656) or isopropyl alcohol (Material No.CP1041) and dry compressed air.
(4) Lubricate the new AIPC 78-31-16-01-040 PREFORMED PACKING (10) with thrust reverser hydraulic fluid.
(5) Install the preformed packing (10) and a new AIPC 78-31-16-01-030 BACKUP RING (20) on the pressure switch.
(6) Install the pressure switch :

CAUTION: MAKE SURE THERE IS NO UNWANTED MATERIAL IN THE PORTS AND ORIFICES OR DAMAGE CAN OCCUR.

(a) Put the pressure switch on the HCU.
(7) Apply Non Hardening Jointing Putty-Medium Temp. Area - - (Material No.06LCG9) on to the 3 bolts and attach the pressure switch.
(8) TORQUE the bolts to between 17 and 13 lbf.in (0.19 and 0.15 m.daN )

(9) Safety the screws with CP8001lockwire 0.032 in. (0.8 mm) dia. or CP8002lockwire 0.032 in. (0.8 mm) dia.
(10) Apply PR 1422A (Material No.CP2428) on to the junction between the HCU and the pressure switch and on to the heads of the screws.
(11) Install the pressure switch.
(12) Tighten the coupling nuts of the switch connectors with PLIERS - NOSE, SOFT, LONG.

5. Close-up
Subtask 78-31-16-440-052-A ** ON A/C NOT FOR ALL

A. Make the thrust reverser serviceable (Ref. AMM TASK 78-30-00-081-041).

Subtask 78-31-16-614-053-A ** ON A/C NOT FOR ALL

B. Pressurization of the hydraulic reservoir :
(1) For engine 1 pressurize the Green hydraulic reservoir (Ref. AMM TASK 29-14-00-614-002).
(2) For engine 2 pressurize the Yellow hydraulic reservoir (Ref. AMM TASK 29-14-00-614-002).

Subtask 78-31-16-410-053-A ** ON A/C NOT FOR ALL

C. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Close the fan cowl doors (Ref. AMM TASK 71-13-00-410-040):
(a) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(b) FOR [1000EM2] (ENGINE-2)
447AL 448AR
(3) Remove the access platform(s).
(4) Remove the WARNING NOTICE(S).

Subtask 78-31-16-710-051-A ** ON A/C NOT FOR ALL

D. Bleed the air from the thrust reverser hydraulic system. (Ref. AMM TASK 78-30-00-710-040)

[Rev.10 from 2021] 2026.04.01 03:20:30 UTC