Adjustment of the Reference CLOSED Position of the VBV System [CFMB]

TASK 75-31-00-820-001-A
Adjustment of the Reference CLOSED Position of the VBV System

FIN: 1000EM1 ** ON A/C NOT FOR ALL
FIN: 1000EM2 ** 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 2M (6 FT) - ADJUSTABLE
No specific	AR	WARNING NOTICE(S)
856A2501	1	WRENCH-VBV MANUAL CONTROL
856A2664	1	GAGE, SETTING - VBV DOORS

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
FOR [1000EM1] (ENGINE-1)
437AL, 438AR, 451AL, 452AR
FOR [1000EM2] (ENGINE-2)
447AL, 448AR, 461AL, 462AR

C. Referenced Information

REFERENCE	DESIGNATION
TASK 71-13-00-010-040-B	Opening of the Fan Cowl Doors
TASK 71-13-00-410-040-B	Closing of the Fan Cowl Doors
TASK 72-23-00-000-027-A	Removal of the Fan Duct Panels
TASK 72-23-00-400-027-A	Installation of the Fan Duct Panels
TASK 75-31-20-000-002-A	Removal of the Bleed Valve Stop Mechanism
TASK 75-31-20-400-002-A	Installation of the Bleed Valve Stop Mechanism
TASK 75-31-30-000-001-A	Removal of a VBV Inter-connecting Flexible Shaft (Typical).
TASK 75-31-30-400-001-A	Installation of a VBV Inter-connecting Flexible Shaft (Typical)
TASK 78-30-00-081-041-B	Make the Thrust Reverser Serviceable after Maintenance
TASK 78-30-00-481-041-B	Make the Thrust Reverser Unserviceable for Maintenance
TASK 78-36-00-010-040-B	Opening of the Thrust Reverser Doors
TASK 78-36-00-410-040-B	Closing of the Thrust Reverser Doors
Adjustment of the Reference CLOSED Position of the VBV Doors (Typical)

3. Job Set-up
Subtask 75-31-00-941-061-A ** ON A/C NOT FOR ALL

A. Safety Precautions
(1) On the center pedestal, on the ENG panel 115VU:
(a) Put a WARNING NOTICE(S) to tell persons not to start the engine.
(2) Make sure that the engine 1(2) shutdown occurred not less than 5 minutes before you do this procedure.
(3) On the overhead maintenance panel 50VU:
(a) Make sure that the ON legend of the ENG/FADEC GND PWR/1(2) pushbutton switch is off.
(b) Put a WARNING NOTICE(S) to tell persons not to energize the FADEC 1(2).

Subtask 75-31-00-010-062-A ** ON A/C NOT FOR ALL

B. Get Access
(1) Open the fan cowl doors (Ref. AMM TASK 71-13-00-010-040):
(a) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(b) FOR [1000EM2] (ENGINE-2)
447AL 448AR
(2) Put the ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE in position.

Subtask 75-31-00-040-056-A ** ON A/C NOT FOR ALL

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

Subtask 75-31-00-010-064-A ** ON A/C NOT FOR ALL

D. Get Access
(1) Open the thrust reverser doors (Ref. AMM TASK 78-36-00-010-040):
(a) FOR [1000EM1] (ENGINE-1)
451AL 452AR
(b) FOR [1000EM2] (ENGINE-2)
461AL 462AR
(2) If applicable, remove the fan duct panels (Ref. AMM TASK 72-23-00-000-027).

4. Procedure
Subtask 75-31-00-820-050-A ** ON A/C NOT FOR ALL

A. Adjustment of the Reference CLOSED Position of the VBV System
(1) Adjust the reference CLOSED position of a VBV door (TYPICAL).
(a) Disengage the flexible shafts ends from the VBV door sockets (Ref. AMM TASK 75-31-30-000-001).
(b) Turn the flexible shaft socket of the ballscrew actuator by hand or with 856A2501 WRENCH-VBV MANUAL CONTROL (856A2501G01) to completely close the VBV door.
(c) Install the 856A2664 GAGE, SETTING - VBV DOORS (856A2664G01) as follows:
1 Position the 2 locator fittings in the reference holes of the VBV door.
2 Push tool against the flexible shaft socket.

NOTE: The tool yoke will not engage if the VBV door is not fully closed.

(d) Turn the flexible shaft socket of the VBV door until the 856A2664 GAGE, SETTING - VBV DOORS (856A2664G01) yoke engages on the flexible shaft socket.
(e) Remove the 856A2664 GAGE, SETTING - VBV DOORS (856A2664G01) after installation of the flexible shafts (Ref. AMM TASK 75-31-30-400-001).
(f) If necessary, use the same procedure to adjust the other VBV doors reference CLOSED position.
(2) Set the VBV stop mechanism to the CLOSED position as follows:
(a) Disengage the flexible shafts ends from the master VBV door and ballscrew actuator (Ref. AMM TASK 75-31-30-000-001).
(b) With the 856A2501 WRENCH-VBV MANUAL CONTROL (856A2501G01), close the master VBV door and ballscrew actuator.
(c) Install the 856A2664 GAGE, SETTING - VBV DOORS (856A2664G01) (Ref. 4. A. (1) (c)) on the master VBV door and ballscrew actuator.
The 856A2664 GAGE, SETTING - VBV DOORS (856A2664G01) yoke must engage on the flexible shaft socket.
If the 856A2664 GAGE, SETTING - VBV DOORS (856A2664G01) yoke can not engage, adjust the stop mechanism reference CLOSED position as follows:
1 Remove the VBV stop mechanism (Ref. AMM TASK 75-31-20-000-002).
2 Set the master VBV door and ballscrew actuator to the reference CLOSED position (Ref. 4. A. (1)).
3 Set the stop mechanism to the CLOSED position and install it (Ref. AMM TASK 75-31-20-400-002).
(d) Install the flexible shafts (Ref. AMM TASK 75-31-30-400-001).

5. Close-up
Subtask 75-31-00-410-062-A ** ON A/C NOT FOR ALL

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) If necessary, install the fan duct panels (Ref. AMM TASK 72-23-00-400-027).
(3) Close the thrust reverser doors (Ref. AMM TASK 78-36-00-410-040):
(a) FOR [1000EM1] (ENGINE-1)
451AL 452AR
(b) FOR [1000EM2] (ENGINE-2)
461AL 462AR

Subtask 75-31-00-440-056-A ** ON A/C NOT FOR ALL

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

Subtask 75-31-00-410-063-A ** ON A/C NOT FOR ALL

C. Close Access
(1) 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
(2) Remove the access platform(s).
(3) Remove the WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.01 13:08:32 UTC