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United States Department of Transportation United States Department of Transportation

AC 33-12 - Geometry and Dimensional Considerations for Comparative Test and Analysis for Turbine Engine and Auxiliary Power Unit (APU) Replacement, and Repaired Parts

Document Information

Number
33-12
Title
Geometry and Dimensional Considerations for Comparative Test and Analysis for Turbine Engine and Auxiliary Power Unit (APU) Replacement, and Repaired Parts
Status
Active
Date issued
2025-09-08
Office of Primary Responsibility
AIR-625, Interactive Org Chart: Engine & Propulsion Section
Description

This advisory circular (AC) provides guidance to support the development of technical data needed to show that an engine or APU replacement part complies with the airworthiness requirements under test and computation, per Title 14, Code of Federal Regulations (14 CFR) 21.303, using the comparative test and analysis approach. This guidance also supports the development of technical data needed for major repairs performed in accordance with 14 CFR Part 43.13(b), where parts fabrication and their implementation must be accomplished “in such a manner that the condition of the aircraft engine or appliance worked on will be at least equal to its original or properly altered condition.” This method supports showing the engine or APU still complies with the applicable airworthiness requirements of 14 CFR Part 33, and Technical Standard Order (TSO) C77.

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