{"id":"F2006B06377","name":"AD/PT6T/7 - Gas Generator Case Seam Weld","slug":"ad-pt6t-7-gas-generator-case-seam-weld","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47649,"registerId":"commonwealth-F2006B06377-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PT6T/7 - Gas Generator Case Seam Weld","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nPratt and Whitney Canada Turbine Engines \\- PT6T Series\n\nAD/PT6T/7 Gas Generator Case Seam Weld 2/88 DM\n\nApplicability: PT6T-3, -3B, -6 engines not incorporating gas generator case stiffening plates fitted in accordance with PT6T-3, \\-3B Overhaul Manual P/N 3017843, Section 72-30-30 or, PT6T-6 Overhaul Manual P/N 3024843, Section 72-31-30 or, during manufacture.\n\nRequirement: 1. Inspect gas generator case for possible seam weld cracking in accordance with PWC ASB No A-5239 paragraph 2A, items 1 to 7.\n\n2. Modify both gas generator case longitudinal (butt) welds in accordance with PWC ASB No A-5239 paragraph 2B, items 1 to 16.\n\nReference Documents: Bell ASB 412-87-30\n\nBell ASB 212-87-45\n\nPWC SIL 5031\n\nPWC SIL 5031 Rev 1\n\nCompliance: 1. (a) All gas generator cases with more than 1200 hours TSN \\- No later than 31 December 1987, and thereafter at intervals not to exceed 600 hours.\n\n(b) All gas generator cases with less than 1200 hours TSN - Prior to 1200 hours TSN or 31 December 1987, whichever occurs later, and thereafter at intervals not to exceed 600 hours.\n\n2. At next power section repair or overhaul.\n\nBackground: The manufacturer advises of eleven reported occurrences of gas generator case seam weld cracking. One occurrence resulted in a gas generator case rupture.","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in specific engine models. It has not expanded beyond its original purpose of preventing gas generator case ruptures."},"complexity_factors":["Short, single-purpose directive with clear mechanical requirements","Only 2 main requirements (inspection and modification)","Simple applicability test based on engine model and presence of stiffening plates","Straightforward compliance timeline based on flight hours (TSN = Time Since New)","References external technical documents (Service Bulletins) but doesn't reproduce their content","No nested exceptions or conditional logic beyond the basic applicability criteria"],"plain_english_summary":"This AD requires operators and maintenance organisations of Pratt & Whitney Canada PT6T-3, PT6T-3B and PT6T-6 engines (without factory-fitted stiffening plates) to inspect the gas generator case seam welds for cracks and to modify the longitudinal welds to prevent future cracking. Issued after multiple seam-weld failures including a complete case rupture, it mandates periodic inspections based on flight hours and modification at the next major overhaul to prevent catastrophic engine failure."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The AD applies to the specific PT6T engine models lacking the stated stiffening plates and to engines during manufacture; nothing in the text indicates an expansion or narrowing of that original applicability beyond the stated models and conditions (Applicability; Background)."},"complexity_factors":["Technical specificity: requires both inspection (items 1–7) and modification (items 1–16) per PWC ASB A‑5239 (Requirement).","Conditional applicability: applies only to PT6T‑3, ‑3B, ‑6 engines that do not have specified stiffening plates or during manufacture (Applicability).","Staggered compliance timing: different initial deadlines based on TSN (<1200 or >1200) and recurring 600‑hour intervals (Compliance 1(a)–(b)).","Repair‑timed modification: weld modification is deferred to next power‑section repair or overhaul, linking mandatory work to scheduled maintenance (Compliance 2).","Cross‑document dependence: implements actions by reference to multiple external documents (PWC ASB A‑5239, Bell ASBs, PWC SILs) which add reading and procurement burden (Reference Documents).","Safety consequence sensitivity: addresses reported in‑service cracking and one rupture, so inspections will require quality control and potentially parts removal (Background)."],"plain_english_summary":"This Airworthiness Directive requires operators and maintainers of Pratt & Whitney Canada PT6T‑3, ‑3B and ‑6 engines (without gas‑generator case stiffening plates, or during manufacture) to inspect for seam‑weld cracking and to modify longitudinal (butt) welds, following Pratt & Whitney Alert Service Bulletin A‑5239 and referenced Bell/PWC documents.\n\nInspections must begin before 31 December 1987 or at 1200 hours TSN as specified and recur every 600 hours; modification is mandated at the next power‑section repair or overhaul. The AD responds to eleven reported cracks and one rupture."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pt6t-7-gas-generator-case-seam-weld","history":"/api/acts/ad-pt6t-7-gas-generator-case-seam-weld/history","analysis":"/api/acts/ad-pt6t-7-gas-generator-case-seam-weld/analysis","conflicts":"/api/acts/ad-pt6t-7-gas-generator-case-seam-weld/conflicts","importantCases":"/api/acts/ad-pt6t-7-gas-generator-case-seam-weld/important-cases","documents":"/api/acts/ad-pt6t-7-gas-generator-case-seam-weld/documents"}}