This SAE Aerospace Recommended Practice (ARP) document establishes criteria and recommended practices for the use of airborne icing tankers to aid in design and certification of aircraft ice protection systems and components. Several icing tankers are described, along with their capabilities and suggested use. Sample data for these tanker spray systems are included, shown with 14 CFR Parts 25 and 29, Appendix C icing envelopes for continuous maximum and intermittent maximum icing conditions. (Note: In the remainder of this document, the phrase "Appendix C icing envelopes" will be used for brevity.) This ARP is intended as a guide toward standard practice and is subject to change to keep pace with experience and technical advances.

Purpose:

The purpose of this document is to support the objective of the "FAA Inflight Aircraft Icing Plan" of establishing acceptance criteria for icing tankers. To this purpose, the document surveys existing airborne icing tanker technology and provides guidance for the acceptance of icing tanker information for certification purposes. The document provides some, but not all, criteria that shall be considered when selecting and using an icing tanker for artificial inflight icing tests. Use of an airborne icing tanker to obtain certification information shall be negotiated with and approved by a certification office, and included in the certification plan for the aircraft.

Background:

The U.S. Federal Aviation Administration established an icing plan in 1997 to respond to a need for a comprehensive program to create an awareness of inflight icing issues and to establish documents to provide training and guidance for regulatory authorities, aircraft operators, research organizations, and aircraft manufacturers. The FAA published a 14-task plan, entitled the "FAA Inflight Aircraft Icing Plan," and identified groups of people within the U.S. Government and throughout the aircraft industry to address the action items contained in this plan. Task 11 of this plan called for the development of "validation criteria and data for simulation methods used to determine ice shapes on aircraft." It also indicated that this task was to include data on "wind tunnel[s], ice accretion computer codes, and icing tankers." The FAA suggested "a coordinated effort among research organizations, industry, and regulatory authorities" and individuals were asked to participate in this work. Task 11 was divided into three subtasks and the people that participated in Subtask A were tasked with addressing criteria for the use of tankers, tunnels, and codes. Three documents were developed by the members of the Task 11.A Working Group and these three documents are being published as SAE ARPs. While each document follows a format that is appropriate to the topic, the three documents provide guidance for the application of codes (ARP5903), tankers (ARP5904), and tunnels (ARP5905) to the icing certification or qualification process.

14 CFR 23.1419(b), 25.1419(b), 27.1419 (c), and 29.1419(c) state that to verify the ice protection analysis, check for icing anomalies, and demonstrate that the ice protection system and its components are effective, the aircraft or its components must be flight tested in measured natural icing conditions and, as found necessary, tested by one or more of the following means: (1) laboratory dry air and/or artificial icing tests, (2) flight dry air tests, and (3) flight tests of the airplane or its components in measured artificial icing conditions. These methods are used in combination to verify analyses, covering the applicable Appendix C icing envelopes. The degree of reliance on each of the methods varies with the applicant. Since it is difficult, often impossible, and sometimes dangerous to cover the entire Appendix C icing envelope in natural icing, icing simulation is generally employed. Properly conducted airborne icing tanker tests can be used to extend natural icing test results to the Appendix C icing envelopes and to verify analyses.