Aircraft Certification Service (AIR) Draft Advisory Circulars (ACs) Open for Comment
| Document Title: | 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 |
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| Summary: | This advisory circular (AC) describes two approaches to define minimum sample sizes of products and articles for turbine aircraft engines and auxiliary power units (APUs) that applicants for a parts manufacturer approval (PMA) may use to show 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 support showing the engine or APU comply with the applicable airworthiness requirements of 14 CFR Part 33 and Technical Standard Order (TSO) C77. |
| Reference: | 14 CFR 21.303(a)(4) 14 CFR 43.13 |
| Documents for Download: | Draft Document Comment Matrix |
| Comments Due: | September 12, 2025 |
| How to Comment: | Email comments to 9-AVS-TechWriters@faa.gov |
Related Information
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Last updated: Wednesday, August 6, 2025