{"id":"F2006B03042","name":"AD/B747/141 - Pylon - Inboard and Outboard Strut Forward Lower Spar","slug":"ad-b747-141-pylon-inboard-and-outboard-strut-forward-lower-spar","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42401,"registerId":"commonwealth-F2006B03042-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/141 - Pylon - Inboard and Outboard Strut Forward Lower Spar","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 747 Series Aeroplanes\n\nAD/B747/141 Pylon \\- Inboard and Outboard Strut Forward Lower Spar\n\n  \n5/95\n\nApplicability: B747 L/N 001 \\- 510 powered by JT9D-3 or \\-7 series engines, excluding JT9D-70 engines.\n\nRequirement: Perform a detailed visual inspection of the Inboard and Outboard Strut Forward Lower Spar Chords, Stiffeners and Web to detect cracks and loose fasteners. Inspect in accordance with Boeing Service Bulletin 747-54-2160.\n\nNote: FAA AD 94-17-17 refers.\n\nCompliance: Initially inspect before 2 February 1996 or before exceeding 6000 landings, whichever is the later.\n\nAircraft that have accumulated between 6000 and 15000 landings shall be inspected before 2 October 1995.\n\nAircraft which have accumulated more than 15000 landings shall be inspected before 2 July 1995.\n\nReinspect at intervals not to exceed 2000 landings or 8000 hours time in service, whichever occurs first.\n\nBackground: There have been five reports of cracks in the subject web. In addition it is suspected that a web crack may have contributed to a recent engine separation.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete airworthiness directive addressing a specific safety defect in a defined aircraft population. It has not expanded beyond its original purpose of mandating inspection for pylon strut cracks."},"complexity_factors":["Single, specific technical requirement (visual inspection per Boeing Service Bulletin)","Limited applicability (specific aircraft line numbers and engine types only)","Three-tiered compliance deadline structure based on landing counts","One cross-reference to FAA AD 94-17-17","No defined terms section or extensive interpretation provisions","Straightforward recurring inspection interval (2000 landings/8000 hours)"],"plain_english_summary":"This safety order requires airlines operating Boeing 747s (line numbers 001–510) with JT9D-3 or JT9D-7 engines to perform detailed visual inspections of the pylon strut forward lower spar for cracks and loose fasteners. It responds to multiple crack reports and a suspected engine separation, so high-use aircraft face earlier deadlines. Inspections must recur every 2,000 landings or 8,000 flight hours to prevent catastrophic failure."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The directive implements inspections for a defined subset of B747s and sets initial and recurring inspection triggers; it does not expand or narrow that stated safety objective within the text provided. Measures align with addressing reported cracks and the suspected link to an engine separation."},"complexity_factors":["Targeted applicability: only B747 line numbers 001–510 with JT9D-3 or -7 engines (excludes JT9D-70) — narrow fleet subset increases need for accurate aircraft identification (Applicability).","Multiple staged initial compliance triggers tied to landing-count bands (≤6000, 6000–15000, >15000) with different deadline dates, creating administrative tracking complexity (Compliance).","Recurring inspection intervals set by either landings or flight hours (every 2000 landings or 8000 hours, whichever first) requiring dual-metric recordkeeping (Compliance).","Mandated inspection procedure is external: must follow Boeing Service Bulletin 747-54-2160, so operators rely on OEM detail and potential SB interpretation (Requirement).","Cross-reference to FAA AD 94-17-17 introduces inter-jurisdictional regulatory alignment considerations (Note).","Safety consequence (possible engine separation) raises urgency and may affect operational availability while inspections are carried out (Background).","Need to detect cracks and loose fasteners via detailed visual inspection can demand skilled maintenance resources and may trigger follow-on repairs."],"plain_english_summary":"This airworthiness directive requires detailed visual inspections of the forward lower spar chords, stiffeners and web on the inboard and outboard struts of specified Boeing 747s (those with JT9D-3 or -7 engines) using Boeing Service Bulletin 747-54-2160. It applies staged initial due dates based on accumulated landings and mandates repeat inspections because cracks have been reported and a web crack may have contributed to an engine separation."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-141-pylon-inboard-and-outboard-strut-forward-lower-spar","history":"/api/acts/ad-b747-141-pylon-inboard-and-outboard-strut-forward-lower-spar/history","analysis":"/api/acts/ad-b747-141-pylon-inboard-and-outboard-strut-forward-lower-spar/analysis","conflicts":"/api/acts/ad-b747-141-pylon-inboard-and-outboard-strut-forward-lower-spar/conflicts","importantCases":"/api/acts/ad-b747-141-pylon-inboard-and-outboard-strut-forward-lower-spar/important-cases","documents":"/api/acts/ad-b747-141-pylon-inboard-and-outboard-strut-forward-lower-spar/documents"}}