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Copyright (2019) General Electric Company, U.S.A.
TRANSMITTAL INFORMATION
REVISION 2 TO SERVICE BULLETIN 72-0357
Revision 2 is issued to update paragraphs 1., PLANNING INFORMATION, 2., MATERIAL INFORMATION, and 3., ACCOMPLISHMENT INSTRUCTIONS.
Revision 1 was issued March 06, 2018. The original was issued February 17, 2017. Revision bars in the left margin identify changes.
1.PLANNING INFORMATION
A.Effectivity
* * * FOR GEnx-1B64, -1B64/P1, -1B64/P2, -1B67, -1B67/P1, -1B67/P2, -1B70, -1B70/75/P1, -1B70/75/P2, -1B70/P1, -1B70/P2, -1B70C/P1, -1B70C/P2, -1B74/75/P1, -1B74/75/P2, -1B76/P2, -1B76A/P2
This Service Bulletin has been introduced in production to these GEnx-1B engines:
•
GEnx-1B engines, serial numbers 956904 and up.
These serial numbers are the best available data.
The A/O vent center tube (center vent tube) P/N 2331M21G02 is affected by this Service Bulletin.
B.Description
This Service Bulletin releases a new center vent tube P/N 2331M21G03.
C.Compliance
Category 7
GE recommends that you do this Service Bulletin at customer's option.
Impact E
This recommendation is to improve the cost of ownership, reduce maintenance requirements or is a product improvement.
NOTE:
This Service Bulletin can be done in shop.
D.Concurrent Requirements
None.
E.Reason
(1)Objective:
To introduce a new part and improve maintainability.
(2)Condition:
Routine teardowns at overhaul shop found tannic oil collected in the mid fan shaft (MFS) with deteriorating paint, seals, coke, and corrosion pittings of the MFS as current center vent tube does not overlap the extension duct over a step of the extension duct. Hence oil can stand just after the seal assembly. This condition contributes the oil leak into the MFS inner.
(3)Cause:
The oil leak into MFS inner cavity is caused by delta pressure between the MFS inner cavity depressurized in high altitude and the center vent tube across seal assembly.
(4)Improvement:
The new center vent tube extends backward by 1.38 inch (35.052 mm), which ensures that the new center vent tube can overlap the extension duct over the step so the oil leak into the MFS inner will be prevented because waterfall condition is ensured and the oil does not stand just after the seal assembly.
(5)Substantiation:
Substantiation is by comparative analysis.
F.Approval
The data contained in this Service Bulletin has been reviewed by the FAA or authorized entity representing the FAA and the repair(s) and modification(s) herein comply with the applicable Aviation Regulations and are APPROVED for installation in the model(s) listed in this Service Bulletin.
G.Manpower
No additional man-hours are required to comply with this Service Bulletin.
H.Weight and Balance
The complete compliance with this Service Bulletin increases weight by 0.250 lb (0.113 kg).
I.References (Use the latest version of this document)
GEK 112851, GEnx-1B Engine Manual (EM)
GEK 112864, GEnx-1B Engine Illustrated Parts Catalog (EIPC)
NOTE:
The reference documents listed below are for the engine manufacturer's internal use only:
CID: 943082
J.Publications Affected
GEK 112851, GEnx-1B Engine Manual (EM)
GEK 112864, GEnx-1B Engine Illustrated Parts Catalog (EIPC)
K.Interchangeability
One-way interchangeable.
L.Software Accomplishment Summary
Not applicable.
2.MATERIAL INFORMATION
A.Material - Price and Availability
(1)Parts necessary to do this Service Bulletin:
 
Part Number
Qty/ Eng
Part Name
Unit ($) Price
Pkg Qty
Lead Time Days
 
2331M21G03
(1)
Duct, A/O Center Vent
12,410.00
(1)
5
NOTE:
Prices are provided for planning purposes and are subject to change.
(2)Other Spare Parts:
None.
(3)Consumables:
None.
B.Industry Support Information
None.
C.Configuration Chart
 
New Part Number
Qty/ Eng
Part Name
Old Part Number/ IPC Location
Qty/ Eng
Op Code
Chg/ Sprt Code
 
(PRODUCTION AND FIELD)
 
2376M20G06/
G07/G08/G09
(X)
Propulsor Module Assembly
(SIN 0010C)
2376M20G06/
G07/G08/G09
(X)
RM
-/-
 
2447M20G01/
G02/G03/G04
(X)
Propulsor Module Assembly
(SIN 0010C)
2447M20G01/
G02/G03/G04
(X)
RM
-/-
 
.2305M64G05
45-011A, 72-00-02
(1)
Shaft, Mid Fan
(SIN 81000)
.2305M64G05
45-011A, 72-00-02
(1)
RM
-/-
 
..2331M21G03
01-020B, 72-58-00
(1)
Tube, A/O Vent Center
(SIN 810A1)
..2331M21G02
01-020A, 72-58-00
(1)
RE
1/B
 
(FIELD ONLY)
 
2376M20G05
(X)
Propulsor Module Assembly
(SIN 0010C)
2376M20G05
(X)
RM
-/-
 
.2305M64G04
45-010A, 72-00-02
(1)
Shaft, Mid Fan
(SIN 81000)
.2305M64G04
45-010A, 72-00-02
(1)
RM
-/-
 
..2331M21G03
01-020B, 72-58-00
(1)
Tube, A/O Vent Center
(SIN 810A1)
..2331M21G02
01-020A, 72-58-00
(1)
RE
1/B
Operation Codes
RE=Replace
RM=Remains
Change Codes
1=One-way interchangeable.
Support Codes
B=Old parts will be supplied until all old parts are sold.
D.Parts Disposition
None.
E.Tooling - Price and Availability
None.
3.ACCOMPLISHMENT INSTRUCTIONS
A.General
(1) Remove the MFS assembly (Figure 1) from the engine as follows:
(a)Remove the low pressure turbine (LPT) module with the MFS assembly. Refer to the GEnx-1B EM, 72-00-04, REMOVAL 001.
(b)Remove the MFS assembly (Figure 1) from the LPT module. Refer to the GEnx-1B EM, 72-00-04, DISASSEMBLY 001.
(2)Disassemble the MFS assembly (Figure 1). Refer to the GEnx-1B EM, 72-58-00, DISASSEMBLY 001, CONFIGURATION 01 or CONFIGURATION 02 and do as follows:
(a)Remove the center vent tube (Figure 1) from the MFS assembly. Refer to the GEnx-1B EM, 72-58-00, DISASSEMBLY 001, CONFIGURATION 01 or CONFIGURATION 02.
 (b)Deleted.
(3)Assemble the MFS assembly with the new center vent tube P/N 2331M21G03. Refer to the GEnx-1B EM, 72-58-00, ASSEMBLY 001, CONFIGURATION 01 or CONFIGURATION 02.
NOTE:
Deleted.
(a)Deleted.
(4)Attach the MFS assembly to the LPT module. Refer to the GEnx-1B EM, 72-00-04, ASSEMBLY 001, CONFIGURATION 01 or CONFIGURATION 02.
(5)Install the LPT module (Figure 1) with the MFS assembly into the propulsor. Refer to the GEnx-1B EM, 72-00-04, INSTALLATION 001.
Center Vent Tube Location
Figure 1   (Sheet 1)
Center Vent Tube Location
Figure 1   (Sheet 2)