{"id":"F2006B06219","name":"AD/PHZL/58 - Piston Nut B474","slug":"ad-phzl-58-piston-nut-b474","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47125,"registerId":"commonwealth-F2006B06219-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PHZL/58 - Piston Nut B474","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nPropellers \\- Variable Pitch \\- Hartzell\n\nAD/PHZL/58 Piston Nut B474 7/89 DM Applicability: All Hartzell propellers model HC-A6A-3 installed on Shorts SD3-60-300 aircraft. Requirement: 1. Action in accordance with Procedure 1 of Hartzell SB No 163.\n\n2. Action in accordance with Procedure 2 of Hartzell SB No 163.\n\nCompliance: For Requirement 1. Within 100 hours time in service from 19 May 1989, or by 9 June 1989 whichever occurs first. Thereafter re-inspect at intervals not exceeding 100 hours time in service until propeller is modified in accordance with Requirement 2.\n\nFor Requirement 2. At next propeller overhaul or by 30 June 1991, whichever occurs first.\n\nBackground: The manufacturer has advised that the B-474 nut may not fully contact the piston when correctly torqued and could cause an inadvertent blade angle change. Pending introduction of a new nut indexing of relevant parts is required.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":3355},"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This appears to be the original issuance of the Airworthiness Directive, establishing the initial regulatory scope to address the specific B-474 piston nut defect in the identified propeller models."},"complexity_factors":["Incorporation by reference of external technical procedures (Hartzell Service Bulletin No 163) without reproducing their content in the instrument","Multiple conditional compliance deadlines using 'whichever occurs first' logic","Recurring inspection obligation that continues until the permanent modification requirement is satisfied","Technical aviation terminology requiring domain knowledge (e.g., 'time in service', 'piston nut', 'torqued', 'blade angle change')"],"plain_english_summary":"This Airworthiness Directive mandates inspections and a permanent modification for Shorts SD3-60-300 aircraft fitted with Hartzell HC-A6A-3 propellers because the B-474 piston nut may not fully contact the piston, risking uncommanded pitch change and loss of thrust/control. \n\nOperators must inspect and index the parts within 100 flight hours from 19 May 1989 (or by 9 June 1989) with repeating 100‑hour checks until the propeller is modified per the service bulletin at overhaul or by 30 June 1991."}},"importantCases":[],"_links":{"self":"/api/acts/ad-phzl-58-piston-nut-b474","history":"/api/acts/ad-phzl-58-piston-nut-b474/history","analysis":"/api/acts/ad-phzl-58-piston-nut-b474/analysis","conflicts":"/api/acts/ad-phzl-58-piston-nut-b474/conflicts","importantCases":"/api/acts/ad-phzl-58-piston-nut-b474/important-cases","documents":"/api/acts/ad-phzl-58-piston-nut-b474/documents"}}