GM3 MMEL.145 Justification of MMEL items

• ED Decision 2020/012/R found in: CS-MMEL Issue 3 - Master Minimum Equipment List (May 2021)
• ED Decision 2025/021/R found in: CS-MMEL Issue 4 - Master Minimum Equipment List (Oct 2026)

GM3 MMEL.145 Justification of MMEL items ED Decision 2020/012/R ELECTRONIC ENGINE CONTROL SYSTEM (EECS) FAILURES — ENGINE TIME-LIMITED DISPATCH (TLD) **1. Dispatch with engine faults covered by a TLD report** (a) If a dispatch is sought with faults (or a combination of faults) that are present in an electronic engine control system (EECS), a time-limited dispatch (TLD) approval is required, as per Ref. [1] CS-E 1030, for faults such as EECS degraded protection or a loss of redundancy against a loss of thrust control (LOTC)/loss of power control (LOPC). (b) A TLD approval is granted once the engine manufacturer has demonstrated compliance with the applicable engine certification requirements, including the verification that the LOTC/LOPC rates and hazardous engine effect rates remain acceptable with the proposed rectification time limits. (c) Engine system faults that do not have an impact on the LOTC rate, or on the compliance with the applicable engine certification requirements, may nevertheless be included as part of the TLD report. These faults are normally indicated as not being derived from the LOTC analysis in the TLD report. In line with FAA Policy No. ANE-1993-33.28TLD-R1, a complete loss of a critical resource or a critical function should be a ’No Dispatch’ configuration in the TLD report. A resource or a function should be considered critical if it is necessary to comply with CS-E 1030(b) and/or (c). (d) When taking credit for the TLD analysis to demonstrate compliance with CS-MMEL, the aircraft manufacturer should ensure that the MMEL content remains consistent with the TLD restrictions, time limitations, and other related installation requirements set by the engine manufacturer. **2. Evaluation of aircraft-level consequences for MMEL evaluation** (a) When engine-related MMEL items are involved in aircraft level failure conditions that are classified as hazardous or catastrophic, compliance with the applicable requirements for qualitative and quantitative analysis should be demonstrated, as for any candidate MMEL item. Contributions from the engine control system to the aircraft functional hazard assessment (FHA)/system safety assessment (SSA) may be affected, and may need to be re-evaluated. In such cases, coordination between the aircraft and the engine manufacturers is necessary to complete the demonstration of compliance of the MMEL. (b) It is recommended that the aircraft manufacturer’s MMEL safety analysis should be made prior to the definition of the generic cockpit messages related to the TLD categories (short-term and long-term) in order to avoid re-design issues. **3. Dispatch with EECS faults with performance effects** (a) Particular attention should be paid to range-sensitive operations, including LROPS and ETOPS, when engine system faults, including some that are included in the TLD analysis, could have an effect on the fuel consumption, and hence on the range, of the aircraft. (b) Normally, degraded performance is not analysed by the engine manufacturer for LOTC, but it should be assessed by the aircraft manufacturer. (c) Flight duration and thrust variation in the event of an in-flight shut down (IFSD) should be considered in the performance /range assessment. If necessary, operational limitations should be specified in the MMEL for authorised combinations of MMEL items. **4. Allocation of MMEL rectification intervals** (a) When a TLD approval is granted at the engine level, the repair limitations for short-term or long‑term faults may be used by the aircraft manufacturer to support the allocation of the appropriate MMEL rectification interval. (b) If the repair intervals are taken from the TLD analysis, the corresponding MMEL items should be allocated an ‘A’ category rectification interval (with no extension possible). Issue No: MMEL/2 GM3 MMEL.145 Justification of MMEL items ED Decision 2020/012/R ELECTRONIC ENGINE CONTROL SYSTEM (EECS) FAILURES — ENGINE TIME-LIMITED DISPATCH (TLD) **1. Dispatch with engine faults covered by a TLD report** (a) If a dispatch is sought with faults (or a combination of faults) that are present in an electronic engine control system (EECS), a time-limited dispatch (TLD) approval is required, as per Ref. [1] CS-E 1030, for faults such as EECS degraded protection or a loss of redundancy against a loss of thrust control (LOTC)/loss of power control (LOPC). (b) A TLD approval is granted once the engine manufacturer has demonstrated compliance with the applicable engine certification requirements, including the verification that the LOTC/LOPC rates and hazardous engine effect rates remain acceptable with the proposed rectification time limits. (c) Engine system faults that do not have an impact on the LOTC rate, or on the compliance with the applicable engine certification requirements, may nevertheless be included as part of the TLD report. These faults are normally indicated as not being derived from the LOTC analysis in the TLD report. In line with FAA Policy No. ANE-1993-33.28TLD-R1, a complete loss of a critical resource or a critical function should be a ’No Dispatch’ configuration in the TLD report. A resource or a function should be considered critical if it is necessary to comply with CS-E 1030(b) and/or (c). (d) When taking credit for the TLD analysis to demonstrate compliance with CS-MMEL, the aircraft manufacturer should ensure that the MMEL content remains consistent with the TLD restrictions, time limitations, and other related installation requirements set by the engine manufacturer. **2. Evaluation of aircraft-level consequences for MMEL evaluation** (a) When engine-related MMEL items are involved in aircraft level failure conditions that are classified as hazardous or catastrophic, compliance with the applicable requirements for qualitative and quantitative analysis should be demonstrated, as for any candidate MMEL item. Contributions from the engine control system to the aircraft functional hazard assessment (FHA)/system safety assessment (SSA) may be affected, and may need to be re-evaluated. In such cases, coordination between the aircraft and the engine manufacturers is necessary to complete the demonstration of compliance of the MMEL. (b) It is recommended that the aircraft manufacturer’s MMEL safety analysis should be made prior to the definition of the generic cockpit messages related to the TLD categories (short-term and long-term) in order to avoid re-design issues. **3. Dispatch with EECS faults with performance effects** (a) Particular attention should be paid to range-sensitive operations, including LROPS and ETOPS, when engine system faults, including some that are included in the TLD analysis, could have an effect on the fuel consumption, and hence on the range, of the aircraft. (b) Normally, degraded performance is not analysed by the engine manufacturer for LOTC, but it should be assessed by the aircraft manufacturer. (c) Flight duration and thrust variation in the event of an in-flight shut down (IFSD) should be considered in the performance /range assessment. If necessary, operational limitations should be specified in the MMEL for authorised combinations of MMEL items. **4. Allocation of MMEL rectification intervals** (a) When a TLD approval is granted at the engine level, the repair limitations for short-term or long‑term faults may be used by the aircraft manufacturer to support the allocation of the appropriate MMEL rectification interval. (b) If the repair intervals are taken from the TLD analysis, the corresponding MMEL items should be allocated an ‘A’ category rectification interval (with no extension possible). Issue No: MMEL/2 ##### GM3 MMEL.145 Justification of MMEL items *ED Decision 2025/021/R* **ELECTRONIC ENGINE CONTROL SYSTEM (EECS) FAILURES — ENGINE TIME-LIMITED DISPATCH (TLD)** **1. Dispatch with engine faults covered by a TLD report** (a) If a dispatch is sought with faults (or a combination of faults) that are present in an electronic engine control system (EECS), a time-limited dispatch (TLD) approval is required, as per Ref. [1] CS-E 1030, for faults such as EECS degraded protection or a loss of redundancy against a loss of thrust control (LOTC)/loss of power control (LOPC). (b) A TLD approval is granted once the engine manufacturer has demonstrated compliance with the applicable engine certification requirements, including the verification that the LOTC/LOPC rates and hazardous engine effect rates remain acceptable with the proposed rectification time limits. (c) Engine system faults that do not have an impact on the LOTC rate, or on the compliance with the applicable engine certification requirements, may nevertheless be included in a non-approved part of the TLD report. These faults are normally indicated as not being derived from the LOTC analysis in the TLD report. In line with FAA Policy No. ANE-1993-33.28TLD-R1, a complete loss of a critical resource or a critical function should be a ’No Dispatch’ configuration in the TLD report. A resource or a function should be considered critical if it is necessary to comply with CS-E 1030(b) and/or (c). (d) When taking credit for the TLD analysis to demonstrate compliance with CS-MMEL, the aircraft manufacturer should ensure that the MMEL content remains consistent with the TLD restrictions, time limitations, and other related installation requirements set by the engine manufacturer. **2. Evaluation of aircraft-level consequences for MMEL evaluation** (a) When engine-related MMEL items are involved in aircraft level failure conditions that are classified as hazardous or catastrophic, compliance with the applicable requirements for qualitative and quantitative analysis should be demonstrated, as for any candidate MMEL item. Contributions from the engine control system to the aircraft functional hazard assessment (FHA)/system safety assessment (SSA) may be affected, and may need to be re-evaluated. In such cases, coordination between the aircraft and the engine manufacturers is necessary to complete the demonstration of compliance of the MMEL. (b) It is recommended that the aircraft manufacturer’s MMEL safety analysis should be made prior to the definition of the generic cockpit messages related to the TLD categories (short-term and long-term) in order to avoid re-design issues. **3. Dispatch with EECS faults with performance effects** (a) Particular attention should be paid to range-sensitive operations, including LROPS and ETOPS, when engine system faults, including some that are included in the TLD analysis, could have an effect on the fuel consumption, and hence on the range, of the aircraft. (b) Normally, degraded performance is not analysed by the engine manufacturer for LOTC, but it should be assessed by the aircraft manufacturer. (c) Flight duration and thrust variation in the event of an in-flight shut down (IFSD) should be considered in the performance /range assessment. If necessary, operational limitations should be specified in the MMEL for authorised combinations of MMEL items. **4. Allocation of MMEL rectification intervals** (a) When a TLD approval is granted at the engine level, the repair limitations for short-term or long‑term faults may be used by the aircraft manufacturer to support the allocation of the appropriate MMEL rectification interval. (b) If the repair intervals are taken from the TLD analysis, the corresponding MMEL items should be allocated an ‘A’ category rectification interval (with no extension possible).