{"id":"F2006B02636","name":"AD/B727/113 - Aft Mount Support Fittings Engines 1 and 3","slug":"ad-b727-113-aft-mount-support-fittings-engines-1-and-3","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41952,"registerId":"commonwealth-F2006B02636-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/113 - Aft Mount Support Fittings Engines 1 and 3","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)  \nBoeing 727 Series Aeroplanes\n\nAD/B727/113 Aft Mount Support Fittings Engines 1 and 3 2/90\n\nApplicability: All models.\n\nRequirement: Action in accordance with Boeing SB 727-54-0017.\n\nNote: FAA AD 89-23-17 refers.\n\nCompliance: 1. For aircraft with fittings made of 7079-T6 material. Unless previously accomplished within the last 2000 flight cycles prior to 22 February 1990 \\- Prior to exceeding 1000 flight cycles or 1 year after 22 February 1990, whichever occurs first, and thereafter at intervals not exceeding 3000 flight cycles.\n\nNote: 7079-T6 material is used in the aft support fitting on number 1 engine strut on aircraft line numbers 001 through 883, and number 3 engine strut on aircraft line number 001 through 880.\n\n2. For aircraft with fittings made of 7075-T73 material. Unless previously accomplished within the last 2000 flight cycles prior to 22 February 1990 \\- Prior to exceeding 40,000 flight cycles, or within 1000 flight cycles after 22 February 1990 whichever occurs later, and thereafter at intervals not exceeding 3000 flight cycles.\n\nNote: 7075-T73 material is used in the aft support fitting on number 1 engine strut on aircraft line number 884 and later, and on number 3 engine strut on aircraft line number 881 and later.\n\nBackground: Country of origin AD. Cracking has been reported as a result of stress corrosion and fatigue.","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, original safety directive targeting a specific structural defect in a single aircraft type. No scope creep is evident; it remains tightly focused on aft mount support fittings for engines 1 and 3."},"complexity_factors":["Short, single-purpose directive (2 pages)","Only 2 material-specific compliance pathways to track","Cross-references to external documents: Boeing Service Bulletin 727-54-0017 and FAA AD 89-23-17","Time-based and flight cycle-based triggers require operators to maintain accurate records","Aircraft line number cutoffs (001-883 vs 884+) create identification burden for operators"],"plain_english_summary":"CASA’s Airworthiness Directive requires all Boeing 727 operators in Australia to inspect the aft engine mount support fittings on engines 1 and 3, following Boeing SB 727-54-0017, to detect cracks from stress corrosion and fatigue. \n\nThis is legally mandatory: failing fittings can allow engine separation, so operators must follow the SB’s inspection schedules (different for older and newer fittings)."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The directive applies to all Boeing 727 models and records material- and line-number-based inspection timing; it specifies inspection and recurring intervals to address reported cracking and does not expand applicability beyond the stated aircraft or introduce additional component categories."},"complexity_factors":["Two material-specific compliance tracks (7079-T6 versus 7075-T73) with different initial deadlines","Deadlines tied both to a calendar reference date (22 February 1990) and to flight-cycle counts","Recurrent inspection interval set at not exceeding 3000 flight cycles","Applicability to all models but material usage varies by aircraft line numbers, requiring determination of line number or part material","Mandates compliance with an external Boeing Service Bulletin (SB 727-54-0017) rather than spelling out specific inspection procedures","Operators must establish and track flight cycles and prior accomplishment within specified retrospective windows (last 2000 cycles prior to 22 Feb 1990)","Cross-reference to FAA AD increases coordination/research burden for some operators","Technical risk basis (stress corrosion and fatigue) requires appropriate inspection/repair capability"],"plain_english_summary":"This airworthiness directive requires operators of Boeing 727 aircraft to carry out inspection and any corrective action for the aft engine mount support fittings on engines 1 and 3, following Boeing Service Bulletin 727-54-0017. It sets different initial inspection windows and recurring inspection intervals depending on the fitting material and aircraft production line, because cracking from stress corrosion and fatigue has been reported. Operators must identify fitting material and flight-cycle counts, schedule inspections within the specified windows, and pay for and perform any required work."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-113-aft-mount-support-fittings-engines-1-and-3","history":"/api/acts/ad-b727-113-aft-mount-support-fittings-engines-1-and-3/history","analysis":"/api/acts/ad-b727-113-aft-mount-support-fittings-engines-1-and-3/analysis","conflicts":"/api/acts/ad-b727-113-aft-mount-support-fittings-engines-1-and-3/conflicts","importantCases":"/api/acts/ad-b727-113-aft-mount-support-fittings-engines-1-and-3/important-cases","documents":"/api/acts/ad-b727-113-aft-mount-support-fittings-engines-1-and-3/documents"}}