The purpose of this document is to define the power spectrum during normal and emergency operations of a twin engine helicopter and thereby to postulate suitable power plant rating structures. The document does not address the power requirements for single engine helicopters or those with more than two engines.
Rationale: This document has been updated to include the new regulations about Cat a and cat b. the document is also reviewed in the areas of power spectrum, FADEC control and engine ratings. Minor editorial changes in the tables and the acronym list.
