ETSO-C55a A1

• ED Decision 2022/018/R found in: CS-ETSO Amdt 17 - European Technical Standard Orders (Oct 2026)

#### ETSO-C55a A1 *ED Decision 2022/018/R* ##### **Fuel and Oil Quantity Instruments** **1 Applicability** This ETSO provides the requirements that fuel and oil quantity instruments that are designed and manufactured on or after the date of this ETSO must meet in order to be identified with the applicable ETSO marking. **2 Procedures** 2.1 General The applicable procedures are detailed in CS-ETSO [Subpart A](#_DxCrossRefBm920220672). 2.2 Specific None. **3 Technical Conditions** 3.1 Basic 3.1.1 Minimum Performance Standard The applicable standards are those provided in: — SAE Aerospace Standard (AS) 405C ‘Fuel and oil quantity Instruments’, dated July 2001; or — SAE Aerospace Standard (AS) 405D ‘Fuel and oil quantity Instruments’, dated August 2012, both modified by Appendix 1 to this ETSO. 3.1.2 Environmental Standard See CS-ETSO, Subpart A, paragraph 2.1. As specified in SAE Aerospace Standard AS405C or AS405D. 3.1.3 Software See CS-ETSO, Subpart A, paragraph 2.2. 3.1.4 Airborne Electronic Hardware See CS-ETSO, Subpart A, paragraph 2.3. 3.2 Specific 3.2.1 Failure Condition Classification See CS-ETSO, Subpart A, paragraph 2.4. The failure condition classification will depend on the system on which the fuel and oil quantity instrument is installed. The classification must be determined by the safety assessment conducted as part of the installation approval. Each fuel and oil quantity instrument shall be developed to at least the design assurance level assumed to be assigned to the system on which the fuel and oil quantity instrument will be installed. **4 Marking** 4.1 General See CS-ETSO, Subpart A, paragraph 1.2. 4.2 Specific At least one major component must be permanently and legibly marked with all the information in SAE AS405C or AS405D, Section 3.2 (except paragraph 3.2.b). Also, the component must be marked with the following information: (1) The basic type and accuracy classification, and (2) The fluids for which the instrument is substantiated. **5 Availability of Referenced Documents** See CS-ETSO, Subpart A, paragraph 3. [Amdt ETSO/7] [Amdt ETSO/17]