{"id":"F2006B06143","name":"AD/PC-6/39 - Wing Spar and Lift Strut Fatigue Lives","slug":"ad-pc-6-39-wing-spar-and-lift-strut-fatigue-lives","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":46935,"registerId":"commonwealth-F2006B06143-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PC-6/39 - Wing Spar and Lift Strut Fatigue Lives","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Pilatus Porter PC-6 Series Aeroplanes\n\n \n\nAD/PC-6/39 Wing Spar and Lift Strut Fatigue Lives 7/93\n\nApplicability: All PC-6 series aircraft.\n\n \n\nRequirement: Retire the main spar and lift strut on each wing.\n\n \n\nCompliance: Retire each component before it achieves10000 hours time in service.\n\n \n\nNote: Operation beyond 10000 hours may be permitted if the components are inspected in accordance with a Supplemental Structural Inspection Program (SSIP) approved by the Authority.\n\n \n\nBackground: The life limits are based on the limited available fatigue data. There may be scope for the Authority to approve an increase after receipt of further analysis of worldwide fleet data and development of a SSIP.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive focused specifically on fatigue life limits for two structural components. It has not expanded beyond its original safety purpose."},"complexity_factors":["Single, unambiguous requirement (retire components at 10,000 hours)","Only one defined term implicitly used ('time in service')","Single exception/qualification (SSIP approval for extended operation)","No cross-references to other legislation or regulations","Extremely short document (approximately 150 words of substantive content)","Clear applicability statement with no conditional logic"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that applies to all Pilatus Porter PC-6 series aircraft.\n\n**What it does:**\n- Sets a **hard retirement deadline** for two critical structural components: the main wing spar (the central beam that holds the wing together) and the lift strut (the support that helps carry the wing's load).\n- These parts must be **permanently removed from service** before they reach **10,000 hours of flight time**.\n\n**Who it affects:**\n- Owners and operators of all Pilatus PC-6 aircraft in Australia.\n- Maintenance organisations servicing these planes.\n\n**Why it matters:**\n- **Safety-critical:** Metal fatigue in wing structures can lead to catastrophic failure. This rule prevents planes from flying with potentially dangerous structural wear.\n- **Flexibility built in:** Operators can fly beyond 10,000 hours **only if** they implement an approved enhanced inspection program (called an SSIP) to catch cracks before they become dangerous.\n- **Based on limited data:** The 10,000-hour limit is conservative because fatigue data was scarce when this directive was issued. CASA left the door open to extending the limit if more data proves it's safe.\n\n**In short:** This is a \"use-by date\" for key wing parts, with a possible extension if you're willing to do extra safety checks."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The source text does not indicate a change in scope from any earlier instrument. The directive establishes a life limit for main spars and lift struts on all PC‑6 aircraft (Applicability; Requirement; Compliance) and provides an approval route for exceptions via an Authority‑approved SSIP (Note). The Background notes only that limits are based on limited fatigue data and could be increased after further analysis and SSIP development; it does not state that the directive reduced or expanded scope relative to a prior stated intent."},"complexity_factors":["Single clear prescriptive requirement (retire main spar and lift strut) with a single numeric threshold (10,000 hours). (Requirement; Compliance)","Applicability is simple and universal for the type: all PC‑6 series aircraft. (Applicability)","There is an exception pathway (continued operation under Authority‑approved SSIP) that introduces administrative discretion and process complexity. (Note)","Outcome contingent on future data and analysis: Background contemplates possible changes after receipt of worldwide fleet data and a developed SSIP, adding conditional regulatory uncertainty. (Background)","Implementation requires routine tracking of component hours and coordination for replacement/inspection, which imposes operational and recordkeeping tasks on operators. (Compliance; Note)"],"plain_english_summary":"The directive requires retirement and replacement of main wing spars and lift struts on Pilatus PC‑6 aircraft at 10,000 flight hours unless operated under a Civil Aviation Safety Authority‑approved Supplemental Structural Inspection Program (SSIP). It directly affects PC‑6 owners/operators, who bear replacement costs, recordkeeping and inspection burdens, and creates an incentive to supply fleet fatigue data for possible SSIP approval or future life‑limit increases — concentrating decision‑making and uncertainty with the regulator."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pc-6-39-wing-spar-and-lift-strut-fatigue-lives","history":"/api/acts/ad-pc-6-39-wing-spar-and-lift-strut-fatigue-lives/history","analysis":"/api/acts/ad-pc-6-39-wing-spar-and-lift-strut-fatigue-lives/analysis","conflicts":"/api/acts/ad-pc-6-39-wing-spar-and-lift-strut-fatigue-lives/conflicts","importantCases":"/api/acts/ad-pc-6-39-wing-spar-and-lift-strut-fatigue-lives/important-cases","documents":"/api/acts/ad-pc-6-39-wing-spar-and-lift-strut-fatigue-lives/documents"}}