This advisory circular (AC) provides guidance for developing substantiation data to support the design approval of critical and complex turbine engine and auxiliary power unit (APU) parts produced under parts manufacturer approval (PMA).

This advisory circular (AC) provides guidance and acceptable means, but not the only means, for demonstrating compliance with the specific requirements applicable to 30-second and 2-minute One-Engine-Inoperative (OEI) rotorcraft turbine engine ratings in part 33 of Title 14 of the Code of Federal Regulations (14 CFR part 33).

These equivalencies relate to oxidation, hot corrosion, and thermal fatigue and erosion characteristics in the engine environment.

This AC applies to certain sections of Title 14 of the Code of Federal Regulations (14 CFR) parts 21, 33, and 45, and describes or references methods of compliance that may be acceptable for engine type certification work.