**FUEL SYSTEM - Fuel System (73-00-00) - Visual Inspection for Fuel Filter Differential Pressure Switch Cracks** 
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July 08, 2011 CT7-8 S/B 73-A0007 PAGE 1 of 9**FUEL SYSTEM - Fuel System (73-00-00) - Visual Inspection for Fuel Filter Differential Pressure Switch Cracks**  1. P LA N N I N G I N F O R M A T I O N A. E ff e ct i v i ty This Alert Service Bulletin is applicable to: CT7-8/-8A/-8A1/-8A5/-8B/-8B5/-8E/-8E5/-8F/-8F5 engine models. B. D e s c r i p t i o n This Alert Service Bulletin recommends a daily visual inspection and provides criteria for cracks on the fuel fi lter differential pressure switch (differential pressure switch) P/N TD028VF0H7Y5. C. C o m p l i a n c e Category 2 GE recommends that you do this Alert Service Bulletin on a DAILY interval. N O T E : This Alert Service Bulletin can be accomplished on-wing. This Alert Service Bulletin is offered to improve the reliability or performance of your GE product, or to help prevent the occurrence of the event or condition described in this Alert Service Bulletin. If the operator elects not to participate in the bulletin, that decision will be taken into consideration by GE in evaluating future product performance issues that may arise in the operator’s fl eet. D. C o n c u r re n t R e q u i re m e n t s None. E. R e a s o n (1) Objective: To reduce signi fi cant events by performing daily fuel fi lter differential pressure switch fl ange inspections per Accomplishment Instructions in paragraph 3. (2) Condition: CT7-8 engines may display cracking across the two bolt hole fl anges of the differential pressure switch, P/N TD028VF0H7Y5. The differential switch is part of the fuel fi lter assembly (P/N 4110T53P06), located on the accessory gearbox. (3) Cause: High stresses causing anodized coating to crack and associated buildup of corrosion.

July 08, 2011 CT7-8 S/B 73-A0007 PAGE 2 GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or fi rst page.**FUEL SYSTEM - Fuel System (73-00-00) - Visual Inspection for Fuel Filter Differential Pressure Switch Cracks**  (4) Substantiation: Substantiation for the inspection requirement and allowable crack criteria is accomplished by CT7-8A fl eet experience (>400,000 fl ight hours) on P/N TD028VF0H7Y5 switches with no events. F. A p p rova l This Service Bulletin has been reviewed by the FAA and the repair(s) and modi fi cation(s) herein comply with the applicable Federal Aviation Regulations and are FAA APPROVED for installation in the model(s) listed in this Service Bulletin. G. M a n p o w e r After you get access to the fuel fi lter assembly, you will need approximately 10 minutes for each engine or component. H. We i g h t a n d B a l a n ce Weight and balance are not changed. I. R e f e re n c e s (Use the latest version of this document) GEK 105159, CT7-8 Maintenance Manual (MM) J. P u b l i c at i o n s Aff e ct e d Not applicable. K. I n t e rc h a n g e a b i l i ty Not applicable. L. S o ftw a re A cc o m p l i s h m e n t S u m m a ry Not applicable. 2. M A T E R I A L I N F O R M A T I O N A. M at e r i a l
- P r i ce a n d Ava i l a b i l i ty (1) Parts necessary to do this Alert Service Bulletin: None.

July 08, 2011 CT7-8 S/B 73-A0007 PAGE 3 GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or fi rst page.**FUEL SYSTEM - Fuel System (73-00-00) - Visual Inspection for Fuel Filter Differential Pressure Switch Cracks**  (2) Other Spare Parts:

P a rt N u m b e r Q ty/ E n g P a rt N a m e U n i t ( $ ) P r i c e P kg Q ty L e a d Ti m e D ays TD028VF0H7Y5
or (1) Switch, Differential Pressure Quote (-) Quote

TD028VF0H7Y4 (1) Switch, Differential Pressure Quote (-) Quote

N O T E : If TD028VF0H7Y5 is not immediately available, then replace with TD028VF0H7Y4 and decomply with SB 73-0004. J228P908 (1) Packing, Preformed Quote (-) Quote J228P014 (1) Packing, Preformed Quote (-) Quote
(3) Consumables: None. B. I n d u s t ry S u p p o rt I n fo r m at i o n None. C. C o n fi g u rat i o n C h a rt None. D. P a rt s D i s p o s i t i o n Discard old parts. E. T o o l i n g - P r i c e a n d Ava i l a b i l i ty None. 3. A C C O M P L I S H M E N T I N S T R U C T I O N S A. G e n e ra l N O T E : If TD028VF0H7Y5 is not immediately available, then replace with TD028VF0H7Y4 and decomply with SB 73-0004. Check for fuel leak or evidence of fuel leakage around the fl ange area. A mirror and white light will help with this visual inspection (Figure 2). Cracks are acceptable provided that they are not fully through the fl ange (across the top and continues down one or both sides). If either fl ange is completely separated, the differential July 08, 2011 CT7-8 S/B 73-A0007 PAGE 4 GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or fi rst page.**FUEL SYSTEM - Fuel System (73-00-00) - Visual Inspection for Fuel Filter Differential Pressure Switch Cracks**  pressure switch must be replaced with a new differential pressure switch. Refer to GEK 105159, 73-00-00, REMOVAL 010, and INSTALLATION 010. Then continue with the recommended daily visual inspections, that follow: (1) Cracks partially across the top and continuing partially down one side (VIEW A, Figure 1) - Permitted. (2) Crack completely down one side (VIEW B, Figure 1) - Not Permitted. (3) Cracks partially down both sides (VIEW C, DETAIL D, Figure 1) - Not Permitted. N O T E : **.** Cracks on both ears - Permitted if and only if they both meet the requirements of step 3.A.(1).

**.** Cracks on differential pressure switches on both engines - Not Permitted.

**.** If crack cannot be evaluated, or if switch has any "Not Permitted" conditions, replace the differential pressure switch.

July 08, 2011 CT7-8 S/B 73-A0007 PAGE 5 GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or fi rst page.**FUEL SYSTEM - Fuel System (73-00-00) - Visual Inspection for Fuel Filter Differential Pressure Switch Cracks** 

Visual Inspection of the Differential Pressure Switch P/N TD028VF0H7Y5 Figure 1, ( Sheet 1 of 3 )

July 08, 2011 CT7-8 S/B 73-A0007 PAGE 6 GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or fi rst page.**FUEL SYSTEM - Fuel System (73-00-00) - Visual Inspection for Fuel Filter Differential Pressure Switch Cracks** 

Visual Inspection of the Differential Pressure Switch P/N TD028VF0H7Y5 Figure 1, ( Sheet 2 )

July 08, 2011 CT7-8 S/B 73-A0007 PAGE 7 GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or fi rst page.**FUEL SYSTEM - Fuel System (73-00-00) - Visual Inspection for Fuel Filter Differential Pressure Switch Cracks** 

Visual Inspection of the Differential Pressure Switch P/N TD028VF0H7Y5 Figure 1, ( Sheet 3 )

July 08, 2011 CT7-8 S/B 73-A0007 PAGE 8 GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or fi rst page.**FUEL SYSTEM - Fuel System (73-00-00) - Visual Inspection for Fuel Filter Differential Pressure Switch Cracks** 

Example of Visual Inspection Using Mirror and White Light Figure 2

July 08, 2011 CT7-8 S/B 73-A0007 PAGE 9 GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or fi rst page.