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AC 33-13 - Sample Size Considerations for Comparative Test and Analysis for Turbine Aircraft Engine and Auxiliary Power Unit (APU), Parts Manufacturer Approval (PMA), and Third-Party Repair Parts

Document Information

Number
33-13
Title
Sample Size Considerations for Comparative Test and Analysis for Turbine Aircraft Engine and Auxiliary Power Unit (APU), Parts Manufacturer Approval (PMA), and Third-Party Repair Parts
Status
Active
Date issued
2026-09-16
Office of Primary Responsibility
AIR-625, Interactive Org Chart: Engine & Propulsion Section
Description

This advisory circular (AC) describes two approaches applicants for a parts manufacturer approval (PMA) may use to define minimum sample sizes for turbine aircraft engine and auxiliary power unit (APU) products and articles when statistical data analysis is used. These approaches support showing compliance with the test reports and computations requirements of title 14, Code of Federal Regulations (14 CFR) § 21.303(a)(4), using the comparative test and analysis approach to demonstrate compliance with 14 CFR part 33 and Technical Standard Order (TSO) C77.

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