 | GEnx-1B SERVICE BULLETIN - 73-0034 R02 | Revised: 10/04/2023 |
| SB 73-0034 R02 ENGINE FUEL AND CONTROL - Electronic Engine Control (EEC) (73-21-20) - Introduction of New EEC Configuration with Improved Fuel Flow Signal Circuitry | Issued: 06/16/2014 | |
| GEnx-1B SERVICE BULLETIN - 73-0034 R02 | Revised: 10/04/2023 |
| SB 73-0034 R02 ENGINE FUEL AND CONTROL - Electronic Engine Control (EEC) (73-21-20) - Introduction of New EEC Configuration with Improved Fuel Flow Signal Circuitry | Issued: 06/16/2014 | |
| GE Designated: -CONFIDENTIAL- | |
| The information contained in this document is GE proprietary information and is disclosed in confidence. It is the property of GE and shall not be used, disclosed to others or reproduced without the express written consent of GE, including, but without limitation, it is not to be used in the creation, manufacture, development, or derivation of any repairs, modifications, spare parts, designs, or configuration changes or to obtain FAA or any other government or regulatory approval to do so. If consent is given for reproduction in whole or in part, this notice and the notice set forth on each page of this document shall appear in any such reproduction in whole or part. | |
| This technical data is considered subject to the Export Administration Regulations (EAR) pursuant to 15 CFR Parts 730-774. Transfer of this data by any means to a Non-U.S. Person, whether in the United States or abroad, without the proper U.S. Government authorization (e.g., License, exemption, NLR, etc.), is strictly prohibited. | |
| Copyright (2023) General Electric Company, U.S.A. |
| TRANSMITTAL INFORMATION |
| REVISION 2 TO SERVICE BULLETIN 73-0034 |
| Revision 2 is issued to update paragraphs 1., PLANNING INFORMATION, 2., MATERIAL INFORMATION, 4., APPENDIX - A , and the attached FADEC International Service Bulletin FADEC3/73-049 to Revision 1. |
| Revision 1 was issued December 08, 2014. The original was issued June 16, 2014. 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 is applicable to all GEnx-1B engines with an electronic engine control (EEC) VIN 114E9586G8 (P/N 2121M82P06), VIN 114E9586G10 (P/N 2447M85P01), or VIN 115E9084G1 (P/N 2447M85P03). |
| The EEC VIN 114E9586G8 (P/N 2121M82P06), VIN 114E9586G10 (P/N 2447M85P01), and VIN 115E9084G1 (P/N 2447M85P03) are affected by this Service Bulletin. |
| B. | Description |
| This Service Bulletin releases new EECs VIN 114E9586G11 (P/N 2121M82P07), VIN 114E9586G12 (P/N 2447M85P02), and VIN 115E9084G2 (P/N 2447M85P04), with improved weight of fuel measure (WFM) signal detection circuitry, and provides accomplishment instructions to modify existing EECs to the new configuration. |
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| Refer to attached FADEC International Service Bulletin FADEC3/73-049 (latest version). |
| C. | Compliance |
| Category 6 |
| GE Recommends that you do this Service Bulletin when the EEC is routed for repair to correct the engine fuel flow display or fuel flow signal faults. |
| Impact E |
| This recommendation is to improve the cost of ownership, reduce maintenance requirements or is a product improvement. |
| NOTE: |
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| This 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 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 fleet. |
| D. | Concurrent Requirements |
| None. |
| E. | Reason |
| (1) | Objective: |
| To introduce new parts. |
| (2) | Condition: |
| The fuel flow meter indication displayed in the cockpits of GEnx-1B powered aircraft fluctuates intermittently by dropping significantly lower than the actual flow rate for one sample, then returning to the correct flow rate value. The probability and frequency of these signal fluctuations (drop outs) vary based on systemic and operating conditions. |
| (3) | Cause: |
| Coupling between the N2 speed sensor and WFM stop signals is occurring in the J5/P5 connector of the EEC. When this is combined with a secondary pulse from the fuel flow meter, the fuel flow meter stop pulse signal crosses the signal detection threshold of the EEC. This causes the effected sample to read as a significantly reduced flow rate, known as a drop out. This also negatively affects flow rate accuracy. |
| (4) | Improvement: |
| The changes consist of replacing 4 resistors and 4 capacitors with direct replacement components of different values on each of the two main channel boards (MCBs) within the EEC. The result of these changes is to improve both the WFM start and stop signal detection as follows: |
| (a) | Introduce a resonance snubber to eliminate unwanted noise on the WFM input signals. |
| (b) | Raise the WFM signal detection threshold for the start and stop signals from 37 mV and 26 mV respectively to 39 mV for both, to provide additional margin above any noise that may still be present. |
| Refer to attached FADEC International Service Bulletin FADEC3/73-049 (latest version). |
| (5) | Substantiation: |
| Substantiation is by analysis, comparative analysis, and test. |
| F. | Approval |
| This Service Bulletin has been reviewed by the FAA and the repair(s) and modification(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. | Manpower |
| Refer to attached FADEC International Service Bulletin FADEC3/73-049 (latest version). |
| H. | Weight and Balance |
| Weight and balance are not changed. |
| I. | References (Use the latest version of these documents) |
| GEK 112864, GEnx-1B Engine Illustrated Parts Catalog (EIPC) |
| GEK 114001, Component Maintenance Manual (CMM), 73-21-50 |
| FADEC International Service Bulletin FADEC3/73-049, ENGINE FUEL AND CONTROL - ECU Modification – Improvement of Weight of Fuel Measure (WFM) Function and Upgrade of Main Channel Boards (MCBs) to Part Number 392-207-906-0 or 262197983-0906 |
| NOTE: |
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| J. | Publications Affected |
| GEK 112864, GEnx-1B Engine Illustrated Parts Catalog (EIPC) |
| GEK 114001, Component Maintenance Manual (CMM), 73-21-50 |
| K. | Interchangeability |
| For GEnx-1BP2 engine models, the EECs VIN 114E9586G10 (P/N 2447M85P01), VIN 114E9586G12 (P/N 2447M85P02), VIN 115E9084G1 (P/N 2447M85P03), and VIN 115E9084G2 (P/N 2447M85P04) are interchangeable on-engine. |
| For non-GEnx-1B/P2 engine models, the EECs VIN 114E9586G8 (P/N 2121M82P06), VIN 114E9586G11 (P/N 2121M82P07), VIN 114E9586G10 (P/N 2447M85P01), VIN 114E9586G12 (P/N 2447M85P02), VIN 115E9084G1 (P/N 2447M85P03), and VIN 115E9084G2 (P/N 2447M85P04) are interchangeable on-engine. |
| The new EECs VIN 114E9586G11 (P/N 2121M82P07), VIN 114E9586G12 (P/N 2447M85P02), and VIN 115E9084G2 (P/N 2447M85P04) introduce internal improvements that are intended to eliminate fluctuations in the fuel flow cockpit display. Therefore, at the EEC level, the EEC VIN 114E9586G12 (P/N 2447M85P02) must not be modified to the previous EEC VIN 114E9586G10 (P/N 2447M85P01). Likewise, the EEC VIN 114E9586G11 (P/N 2121M82P07) must not be modified to the previous EEC VIN 114E9586G8 (P/N 2121M82P06) and the EEC VIN 115E9084G2 (P/N 2447M85P04) must not be modified to the previous EEC VIN 115E9084G1 (P/N 2447M85P03). |
| L. | Software Accomplishment Summary |
| Not applicable. |
| 2. | MATERIAL INFORMATION |
| A. | Material - Price and Availability |
| (1) | Parts necessary to do this Service Bulletin: |
| Refer to attached FADEC International Service Bulletin FADEC3/73-049 (latest version). |
| (2) | Other Spare Parts: |
| Refer to attached FADEC International Service Bulletin FADEC3/73-049 (latest version). |
| (3) | Consumables: |
| None. |
| B. | Industry Support Information |
| None. |
| C. | Configuration Chart |
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| Operation Codes RE=Replace RM=Remains RW=Rework |
| Change Code 5=Qualified interchangeability. Refer to paragraph 1.K., Interchangeability. |
| Support Code A=Old parts will no longer be supplied. |
| D. | Parts Disposition |
| Rework. |
| E. | Tooling - Price and Availability |
| Refer to attached FADEC International Service Bulletin FADEC3/73-049 (latest version). |
| 3. | ACCOMPLISHMENT INSTRUCTIONS |
| A. | General |
| (1) | Refer to attached FADEC International Service Bulletin FADEC3/73-049 (latest version). |
| 4. | APPENDIX - A |
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