FAA Certification of Rotorcraft Engine Induction System for Ice Protection

The Federal Aviation Regulations, FAR 27. 1093 (b) and FAR 29. 1093(b), require that the turbine engine induction system operate throughout the engine ard aircraft operating envelope without the accumulation of ice that would adversely affect engine operation or cause serious loss of power or thrust under the icing conditions specified in FAR 25, Appendix C. This paper will outline the general methodology required to show compliance with the engine inlet icing requirements of the Federal Aviation Regulations. Snow certification, which is optional, is not discussed. Included in this paper are brief discussions of the various types of inlets, the need for design analyses and the need to consider the effects of ice shedding into the engine fran any unheated surfaces of the helicopter . Various rrethods of certification testing are presented, including dry air tests, tanker and spray rig tests, icing tunnel tests, and natural icing tests. The type of flight data and required instrunentation are also discussed.