{"id":"F2006B05995","name":"AD/PA-42/5 - Major Structural Fatigue Limitations","slug":"ad-pa-42-5-major-structural-fatigue-limitations","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114393,"registerId":"commonwealth-F2006B05995-current","compilationNumber":null,"startDate":"2026-04-03","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PA-42/5 - Major Structural Fatigue Limitations","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nPiper PA-42 (Cheyenne III) Series Aeroplanes\n\nAD/PA-42/5 Major Structural Fatigue Limitations 4/84\n\nApplicability: All models.\n\nRequirement: 1. Retire the wing main spar lower caps and root fittings and the centre beam assembly from service at or before 18750 hours time in service.\n\n2. Retire the fuselage pressurised cabin at or before 13650 pressure cycles.\n\nNote 1: To avoid confusion, it should be noted that the lower spar cap comprises the complete spar cap assembly including the “T” section element together with the nesting angles and reinforcing strips.\n\nNote 2: On the basis of currently available fatigue substantiating data only one spar cap replacement is permitted. This will allow a once only wing life extension for the aircraft from spar cap replacement after which the airframe in its entirety will be retired.\n\nEffective: Forthwith.\n\nBackground: This directive formally promulgates the retirement lives for the above major structural items as determined by full scale fatigue testing.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1745},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive maintains its original scope of establishing mandatory retirement lives for specific fatigue-critical structural components of the PA-42 aircraft based on full-scale fatigue testing data. It does not appear to have expanded beyond this original safety purpose."},"complexity_factors":["Only two specific operational requirements with clear numeric thresholds (18,750 hours and 13,650 cycles)","Limited applicability to a single aircraft series (Piper PA-42)","Two explanatory notes clarifying technical definitions but no complex interpretive provisions","No cross-references to other legislation, regulations, or conditional exceptions"],"plain_english_summary":"This is a mandatory safety rule for owners and operators of **Piper PA-42 Cheyenne III aircraft**. It requires specific major structural parts to be permanently retired (taken out of service forever) once they reach strict usage limits:\n\n- **Wing structure components** (including the main spar lower caps, root fittings, and centre beam assembly) must be retired after **18,750 flight hours**\n- **Pressurised cabin fuselage** must be retired after **13,650 pressurisation cycles** (each time the cabin is pressurised during flight)\n\n**Important limitation:** The wing spar caps can only be replaced **once** to extend the aircraft's life. After that single replacement is used up and the aircraft reaches the hour limit, the entire airframe must be permanently retired from service.\n\nThese retirement limits were established through full-scale fatigue testing (stress testing of actual aircraft parts) to prevent catastrophic structural failures caused by metal fatigue."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-42-5-major-structural-fatigue-limitations","history":"/api/acts/ad-pa-42-5-major-structural-fatigue-limitations/history","analysis":"/api/acts/ad-pa-42-5-major-structural-fatigue-limitations/analysis","conflicts":"/api/acts/ad-pa-42-5-major-structural-fatigue-limitations/conflicts","importantCases":"/api/acts/ad-pa-42-5-major-structural-fatigue-limitations/important-cases","documents":"/api/acts/ad-pa-42-5-major-structural-fatigue-limitations/documents"}}