{"id":"F2006B03047","name":"AD/B747/146 - Engine Strut Wing Seal","slug":"ad-b747-146-engine-strut-wing-seal","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42406,"registerId":"commonwealth-F2006B03047-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/146 - Engine Strut Wing Seal","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/B747/146 Engine Strut Wing Seal 6/95\n\nApplicability: Model 747 series aircraft equipped with General Electric CF6-45 or CF6-50 engines, or Pratt & Whitney JT9D series engines; as listed in Boeing Service Bulletin 747-28- 2160, Revision 1.\n\nRequirement: Install a seal on the wing front spar at each engine strut in accordance with Boeing Service Bulletin 747-28-2160, or 747-28-2160 Revision 1.\n\nNote: FAA AD 95-02-07 Amdt 39-9126 refers.\n\nCompliance: Prior to 16 September 1996.\n\nBackground: The FAA received a report of a fire that occurred due to fuel leakage from the fuel line coupling in the engine strut area along the wing front spar, while the aircraft was on the ground after engine shutdown. This Directive requires certain actions that are intended to ensure that fuel leakage is contained within the strut drainage area.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive's scope aligns with its stated purpose: to require installation of a wing front spar seal on specified 747s to contain fuel leakage from the engine strut area. The stated technical requirement (install seal per Boeing Service Bulletin) and the applicability (specific engines/airframes listed in the bulletin) are consistent with the Background's described safety concern, so the scope has not changed from that original stated intent. (Requirement; Applicability; Background)"},"complexity_factors":["Narrow technical scope limited to a specific retrofit (seal) and defined engine types (Applicability)","Single clear compliance action tied to a specified manufacturer service bulletin (Requirement)","Firm compliance deadline with no stated alternatives or exemptions (Compliance)","Dependence on external technical document (Boeing Service Bulletin) for implementation details (Requirement)","Reference to related foreign regulator action (FAA AD) but no additional cross-jurisdictional procedure included (Note)"],"plain_english_summary":"The Civil Aviation Safety Authority mandates that operators of specified Boeing 747s (CF6‑45/50 or JT9D‑fitted, per Boeing Service Bulletin 747‑28‑2160/Rev 1) install a physical seal at each engine‑strut/wing front spar junction to contain fuel leakage, following a reported ground fire. Compliance (and costs for parts, labour and downtime) is required before 16 September 1996; the AD parallels an FAA directive and relies on the Boeing service bulletin for technical details."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete airworthiness directive with a single, specific safety purpose: preventing fire hazards from fuel leaks in a defined aircraft configuration. It has not expanded beyond its original technical scope."},"complexity_factors":["Very short document (under 200 words)","Only 2 defined applicability criteria (engine types and service bulletin reference)","Single, unambiguous compliance action (install seal per specified bulletin)","One hard deadline with no conditional extensions or exceptions","No nested definitions, cross-references to other legislation, or interpretive provisions","Background provides clear safety rationale without creating additional legal conditions"],"plain_english_summary":"This is a **safety order for specific Boeing 747 aircraft**.\n\n**What it does:**\nIt requires airlines and aircraft operators to install a special seal on the wing of certain Boeing 747 planes. The seal goes on the \"front spar\" (a major structural beam) at each engine mounting point.\n\n**Who it affects:**\n- **Aircraft:** Boeing 747 models fitted with either General Electric CF6-45/50 engines or Pratt & Whitney JT9D engines\n- **Operators:** Airlines or owners of these specific aircraft\n\n**Why it matters:**\nThe US aviation safety authority (FAA) reported a fire caused by fuel leaking from a fuel line coupling in the engine strut area. Without this seal, leaked fuel could escape the proper drainage system and create a fire hazard. This directive ensures any fuel leaks stay contained in the designated drainage area rather than spreading to where they could ignite.\n\n**What had to happen:**\nOperators had to complete this seal installation **before 16 September 1996**.\n\n**Key reference:**\nThe work must follow Boeing Service Bulletin 747-28-2160 (or its Revision 1) — this is the manufacturer's official repair instruction."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-146-engine-strut-wing-seal","history":"/api/acts/ad-b747-146-engine-strut-wing-seal/history","analysis":"/api/acts/ad-b747-146-engine-strut-wing-seal/analysis","conflicts":"/api/acts/ad-b747-146-engine-strut-wing-seal/conflicts","importantCases":"/api/acts/ad-b747-146-engine-strut-wing-seal/important-cases","documents":"/api/acts/ad-b747-146-engine-strut-wing-seal/documents"}}