Commonwealth legislation

AD/CT7/4 - Turbine Rotor Discs

In ForceCTH

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Commonwealth

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legislative instrument

Plain English Summary

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This directive requires operators and maintenance organisations for GE CT7-5A2/7A engines to implement GE Alert Service Bulletins A72-228 and A72-229 (effective 9 Aug 1990) because walnut‑shell cleaning contaminated with steel shot may have reduced low‑cycle fatigue life of certain rotor discs. Affected parts must be inspected, re‑lifed, repaired or replaced and records updated; direct compliance costs fall to the operators/maintainers.

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AD/CT7/4 - Turbine Rotor Discs

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COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

View image in the official source General Electric Turbine Engines - CT7 Series

AD/CT7/4 Turbine Rotor Discs 8/90

Applicability: CT7-5A2/7A.

Requirement: Action in accordance with General Electric Alert SB (CT7-TP series) A72-228 and A72-229.

Compliance: Effective from 9 August 1990.

Background: During a walnut shell-cleaning process at an overhaul facility, a number of stages 1 and 2 gas generator turbine rotor discs and stages 3 and 4 power turbine rotor discs may have been shotpeened inadvertently by walnut shells contaminated with steel shot. As a result, these parts may have a reduced low cycle fatigue (LCF) life. The Service Bulletins nominate the suspect parts and new life cycle limits.

Source text

Sourced from the Federal Register of Legislation (legislation.gov.au), CC BY 4.0.