Visual Inspection of the VBV Main Flexible Shaft and the VBV Inter-connecting Flexible Shafts [CFMB]

TASK 75-31-30-200-002-A
Visual Inspection of the VBV Main Flexible Shaft and the VBV Inter-connecting Flexible Shafts

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	WARNING NOTICE(S)

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 75-31-30-000-001-A	Removal of a VBV Inter-connecting Flexible Shaft (Typical).
TASK 75-31-30-000-002-A	Removal of the VBV System Main Flexible Shaft
TASK 75-31-30-400-001-A	Installation of a VBV Inter-connecting Flexible Shaft (Typical)
TASK 75-31-30-400-002-A	Installation of the VBV System Main Flexible Shaft
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
VBV Main Flexible Shaft and Inter-connecting Flexible Shaft (Typical)

3. Job Set-up
Subtask 75-31-30-941-055-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 FADEC 1(2).

Subtask 75-31-30-010-063-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) 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
(3) Put the ACCESS PLATFORM 1M(3 FT) in position.
(4) Remove all fan duct panels (Ref. AMM TASK 72-23-00-000-027).
(5) Remove the flexible shafts (Ref. AMM TASK 75-31-30-000-001) and (Ref. AMM TASK 75-31-30-000-002).

4. Procedure
Subtask 75-31-30-210-051-A ** ON A/C NOT FOR ALL

A. Visual inspection of the VBV main flexible shaft and of the inter-connecting flexible shafts

INSPECT/CHECK	MAXIMUM SERVICEABLE LIMITS	REMARKS
1.Examine the flexible shaft for damage such as:
A.Waves	The maximum wave amplitude must not be more than 0.020 in. (0.51 mm).	Replace the flexible shaft (Ref. AMM TASK 75-31-30-000-001) and (Ref. AMM TASK 75-31-30-400-001) or (Ref. AMM TASK 75-31-30-000-002) and (Ref. AMM TASK 75-31-30-400-002).
B.Spacing between wires	Not permitted	Replace flexible shaft (Ref. AMM TASK 75-31-30-000-001) and (Ref. AMM TASK 75-31-30-400-001) or (Ref. AMM TASK 75-31-30-000-002) and (Ref. AMM TASK 75-31-30-400-002).
C.Very worn, narrowed or broken wires	Not permitted	Replace flexible shaft (Ref. AMM TASK 75-31-30-000-001) and (Ref. AMM TASK 75-31-30-400-001) or (Ref. AMM TASK 75-31-30-000-002) and (Ref. AMM TASK 75-31-30-400-002).
D.Internal breakage - Flexing test	Flexing of the flexible shaft 2 in. (50.80 mm) while holding both ends must not produce any sudden breakaway during the movement of the flexible shaft. The flexing test must be performed in several different planes.	Replace the flexible shaft (Ref. AMM TASK 75-31-30-000-001) and (Ref. AMM TASK 75-31-30-400-001) or (Ref. AMM TASK 75-31-30-000-002) and (Ref. AMM TASK 75-31-30-400-002).

Subtask 75-31-30-220-051-A ** ON A/C NOT FOR ALL

B. Do a dimensional check of the main and inter-connecting flexible shaft hexagonal end for wear damage as follows:
(1) Measure dimension A (across flats).
Dimension A must be 0.350 in. (8.89 mm) minimum. Replace the shaft if dimension A measures less than this minimum value (Ref. AMM TASK 75-31-30-000-001) and (Ref. AMM TASK 75-31-30-400-001) or (Ref. AMM TASK 75-31-30-000-002) and (Ref. AMM TASK 75-31-30-400-002).
(2) Measure dimension B (across hexagon corners)

PRE SB CFM56-5B 72-0119

Dimension B must be 0.370 in. (9.40 mm) minimum.

END OF PRE SB CFM56-5B 72-0119

POST SB CFM56-5B 72-0119

Dimension B must be 0.385 in. (9.78 mm) minimum.

END OF SB CFM56-5B 72-0119

Replace the shaft if dimension B measures less than this minimum value (Ref. AMM TASK 75-31-30-000-001) and (Ref. AMM TASK 75-31-30-400-001) or (Ref. AMM TASK 75-31-30-000-002) and (Ref. AMM TASK 75-31-30-400-002).

Subtask 75-31-30-220-052-A ** ON A/C NOT FOR ALL

C. Do a dimensional check of the length of the main and inter-connecting flexible shafts as follows:
(1) Measure the dimension of the main flexible shaft.
Dimension C must be between 5.8 in. (147.32 mm) - 5.83 in. (148.08 mm).

Replace the main flexible shaft if dimension C is out of limits (Ref. AMM TASK 75-31-30-000-002) and (Ref. AMM TASK 75-31-30-400-002).

(2) Measure the dimension of the inter-connecting flexible shaft.
Dimension D must be between 6.805 in. (172.85 mm) - 6.845 in. (173.86 mm).

Replace the inter-connecting flexible shaft if dimension D is out of limits (Ref. AMM TASK 75-31-30-000-001) and (Ref. AMM TASK 75-31-30-400-001).

5. Close-up
Subtask 75-31-30-410-059-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) Install the flexible shafts (Ref. AMM TASK 75-31-30-400-001) and (Ref. AMM TASK 75-31-30-400-002).
(3) Install of the fan duct panels (Ref. AMM TASK 72-23-00-400-027).
(4) Close the thrust reverser cowl doors (Ref. AMM TASK 78-36-00-410-040):
(a) FOR [1000EM1] (ENGINE-1)
451AL 452AR
(b) FOR [1000EM2] (ENGINE-2)
461AL 462AR
(5) 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
(6) Remove the access platform(s).
(7) Remove the WARNING NOTICE(S).

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