GM3 to AMC 20-189 -- Additional GM related to the 'Significant' classification

• ED Decision 2020/010/R found in: AMC-20 Amdt 23 - Airworthiness of Products, Parts and Appliances (Jan 2022)

GM3 to AMC 20-189 — Additional GM related to the ‘Significant’ classification ED Decision 2020/010/R In the frame of an engine or propeller TC/STC or of an ETSO article authorisation, the definition of ‘Significant’ is based on the anticipation of a potential effect on the product, system, or equipment function that could lead to a Catastrophic, Hazardous or Major failure condition. The goal is to identify and enhance the visibility of OPRs that may pose potential safety risks at the aircraft installation level (see [AMC 20-189](#_DxCrossRefBm1926189336) paragraph 6.1.4). For example, in the case of an engine TC, a partial or complete loss of thrust or power is regarded as a Minor Engine Effect, whereas it may have a more severe effect at the aircraft level. Unless the engine manufacturer can confirm that the effect at the installation level is no more than Minor, the OPR would be classified as ‘Significant’. The associated assumptions or mitigations are usually recorded through instructions for installing and operating the engine, e.g. in an engine installation manual. In the case of an ETSO authorisation, classification of the failure condition is either based on assumptions defined by the applicant, or mandated through the ETSO standard, and is the basis of the safety analysis at the ETSO article level. An OPR is classified as ‘Significant’ when the OPR may lead to a functional failure associated with a Catastrophic, Hazardous or Major failure condition. [Amdt 20/19] GM3 to AMC 20-189 — Additional GM related to the ‘Significant’ classification ED Decision 2020/010/R In the frame of an engine or propeller TC/STC or of an ETSO article authorisation, the definition of ‘Significant’ is based on the anticipation of a potential effect on the product, system, or equipment function that could lead to a Catastrophic, Hazardous or Major failure condition. The goal is to identify and enhance the visibility of OPRs that may pose potential safety risks at the aircraft installation level (see AMC 20-189 paragraph 6.1.4). For example, in the case of an engine TC, a partial or complete loss of thrust or power is regarded as a Minor Engine Effect, whereas it may have a more severe effect at the aircraft level. Unless the engine manufacturer can confirm that the effect at the installation level is no more than Minor, the OPR would be classified as ‘Significant’. The associated assumptions or mitigations are usually recorded through instructions for installing and operating the engine, e.g. in an engine installation manual. In the case of an ETSO authorisation, classification of the failure condition is either based on assumptions defined by the applicant, or mandated through the ETSO standard, and is the basis of the safety analysis at the ETSO article level. An OPR is classified as ‘Significant’ when the OPR may lead to a functional failure associated with a Catastrophic, Hazardous or Major failure condition. [Amdt 20/19] GM3 to AMC 20-189 — Additional GM related to the ‘Significant’ classification ED Decision 2020/010/R In the frame of an engine or propeller TC/STC or of an ETSO article authorisation, the definition of ‘Significant’ is based on the anticipation of a potential effect on the product, system, or equipment function that could lead to a Catastrophic, Hazardous or Major failure condition. The goal is to identify and enhance the visibility of OPRs that may pose potential safety risks at the aircraft installation level (see AMC 20-189 paragraph 6.1.4). For example, in the case of an engine TC, a partial or complete loss of thrust or power is regarded as a Minor Engine Effect, whereas it may have a more severe effect at the aircraft level. Unless the engine manufacturer can confirm that the effect at the installation level is no more than Minor, the OPR would be classified as ‘Significant’. The associated assumptions or mitigations are usually recorded through instructions for installing and operating the engine, e.g. in an engine installation manual. In the case of an ETSO authorisation, classification of the failure condition is either based on assumptions defined by the applicant, or mandated through the ETSO standard, and is the basis of the safety analysis at the ETSO article level. An OPR is classified as ‘Significant’ when the OPR may lead to a functional failure associated with a Catastrophic, Hazardous or Major failure condition. [Amdt 20/19]