This Aerospace Recommended Practice (ARP) covers a brief discussion of the icing problem in aircraft fuel systems and different means that have been used to test for icing. Fuel preparation procedures and icing tests for aircraft fuel systems and components are proposed herein as a recommended practice to be used in the aircraft industry for fixed wing aircraft and their operational environment only. In the context of this ARP, the engine (and APU) is not considered to be a component of the aircraft fuel system, for the engine fuel system is subjected to icing tests by the engine/APU manufacturer for commercial and specific military applications. This ARP is written mostly to address fuel system level testing. It also provides a means to address the requirements of 14 CFR 23.951(c) and 25.951(c). Some of the methods described in this document can be applied to engine and APU level testing or components of those application domains. This revision does not completely address new developments in ice accretion resulting from internal flow in tubing. This will be addressed in a future revision when more experimental data is available. Some background information on the topic is planned to be available in AIR790.
In order to publish a revision within a one year time frame, I'd like to limit the scope of work for this revision to only updating or correcting the requirements (also includes harmonization between industry documents, giving background information/justification, etc...) and to better define the pass/fail criteria. It will make the document clearer and less prone to interpretation/misinterpretation. At a later time (another revision) we should address the test protocol(s) but it will take more time and will require testing to validate the changes.