AC 33.70-2 - Damage Tolerance of Hole Features in High-Energy Turbine
33.70-2 - Damage Tolerance of Hole Features in High-Energy Turbine
- Date Issued
- August 28, 2009
- Responsible Office
- ANE-111, Aircraft Certification Service Engine & Propeller Directorate - Rulemaking & Policy
This advisory circular (AC) provides definitions, guidance, and acceptable methods, but not the only methods, that may be used to demonstrate compliance with requirements in § 33.70 of Title 14 of the Code of Federal Regulations related to the integrity of engine life-limited parts. Section 33.70 contains requirements applicable to the design and life management of propulsion system life-limited parts, including high-energy rotating parts.
This AC presents a damage tolerance approach which can be used to address manufacturing and operationally-induced anomalies in turbine engine rotating part hole features. This approach can be readily integrated with the existing “safe-life” process for high-energy rotors to produce an enhanced life management process. This approach does not replace existing safe-life methodology but supplements it. In the context of damage tolerance, this AC is not intended to allow operation beyond the component manual life limit set using the existing safe life approach which limits the useful rotor life to the minimum number of flight cycles required to initiate a crack. Rotor failure modes for which full containment of high-energy debris can be demonstrated are excluded from the procedures outlined in this AC and need not be accounted for in the overall risk assessment.
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