{"id":"F2006B03006","name":"AD/B747/105 - Engine Strut Power Feeder/Fuel Tube Clearance","slug":"ad-b747-105-engine-strut-power-feeder-fuel-tube-clearance","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42365,"registerId":"commonwealth-F2006B03006-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/105 - Engine Strut Power Feeder/Fuel Tube Clearance","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/B747/105 Engine Strut Power Feeder/Fuel Tube Clearance 3/92\n\nApplicability: As specified in the requirement document. Requirement: Action in accordance with Boeing SB 747-24A2168 R1.\n\nNote: FAA AD T91-20-51 also refers.\n\nCompliance: Phase 1 \\- prior to 16 March 1992, and thereafter at intervals specified in Boeing SB 747-24A2168 R1 as determined by the results of the Phase inspection.\n\nPhase 2 \\- Prior to 16 March 1993.\n\nNote: Compliance with Phase 2 constitutes terminating action for the repetitive inspections required by Phase 1.\n\nBackground: Boeing have advised that a fire in number two engine strut of a Boeing 747-400 has been attributed to a hole in No 2 strut fuel tube caused by electrical arcing resulting from chafing between the fuel tube and the electrical power feeder cable. This condition may exist on other models of Boeing 747 aircraft.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a targeted safety directive addressing a specific mechanical defect on a specific aircraft type. The scope remains precisely limited to the fuel tube/power feeder clearance issue in Boeing 747 engine struts, exactly as intended when issued."},"complexity_factors":["Very short document (under 300 words)","Only 1 defined term implicitly referenced (the Boeing service bulletin)","Simple two-phase compliance structure with clear deadlines","No nested exceptions or conditional logic","Single cross-reference to FAA AD T91-20-51 for additional context","Straightforward applicability (Boeing 747 series as specified in Boeing document)"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific repairs or inspections on aircraft.\n\n**What it does:**\nThis directive orders owners and operators of **Boeing 747 aircraft** to inspect and fix a dangerous design flaw where an electrical power cable can rub against (\"chafe\") a fuel tube in the engine strut (the structure that holds the engine to the wing). This rubbing can wear a hole in the fuel tube, causing fuel leaks and potentially catastrophic fires — exactly what happened on a Boeing 747-400 where a fire broke out in the number two engine.\n\n**Who it affects:**\n- Airlines and operators flying Boeing 747 series aircraft in Australia\n- Maintenance engineers responsible for these aircraft\n\n**What must be done:**\n- **Phase 1:** Inspect the affected area before 16 March 1992, then repeat inspections at intervals specified by Boeing's service bulletin\n- **Phase 2:** Complete permanent repairs before 16 March 1993\n- Once Phase 2 is done, the repetitive inspections stop\n\n**Why it matters:**\nThis addresses a life-threatening safety defect. Fuel + electrical arcing = fire risk. The directive forces action before more incidents occur."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD text does not indicate any change from an earlier or original intent. It directs action by reference to Boeing SB 747-24A2168 R1 to inspect and correct chafing-related clearance between the engine strut power feeder cable and the fuel tube, sets two compliance phases with specific deadlines, and states that Phase 2 is terminating action for the repetitive Phase 1 inspections (Requirement; Compliance; Background). Applicability is delegated to the referenced service bulletin (Applicability: As specified in the requirement document)."},"complexity_factors":["Reference to an external requirement document (Boeing SB 747-24A2168 R1) rather than detailed technical steps increases dependency on that document for compliance.","Applicability is not specified in the AD text itself ('As specified in the requirement document'), requiring operators to consult the service bulletin to determine whether a particular aircraft is covered.","Two-phase compliance structure with Phase 1 creating a conditional repetitive-inspection regime (intervals determined by inspection results) and Phase 2 as terminating action adds procedural steps.","Safety-critical technical nature of inspections and repairs requires specialist maintenance competence and may involve operational scheduling constraints.","Cross-reference to a foreign regulator's AD (FAA AD T91-20-51) introduces harmonisation aspects for operators subject to multiple jurisdictions."],"plain_english_summary":"### What this instrument does\n\nThis airworthiness directive requires inspections and corrective action on certain Boeing 747 aeroplanes to ensure there is adequate clearance between an engine strut fuel tube and an electrical power feeder cable. The directive directs operators to carry out work \"in accordance with Boeing SB 747-24A2168 R1\" (Requirement: Action in accordance with Boeing SB 747-24A2168 R1). It sets two compliance phases with specific deadlines: Phase 1 inspections must be done prior to 16 March 1992 and then repeated at intervals specified in the Boeing service bulletin as determined by inspection results (Compliance: Phase 1 - prior to 16 March 1992, and thereafter at intervals specified in Boeing SB 747-24A2168 R1 as determined by the results of the Phase inspection). Phase 2 must be completed prior to 16 March 1993 and, once done, ends the repetitive inspections required by Phase 1 (Compliance: Phase 2 - Prior to 16 March 1993; Note: Compliance with Phase 2 constitutes terminating action for the repetitive inspections required by Phase 1).\n\n### Who this affects\n\n- Operators/owners of the Boeing 747 models covered by the referenced service bulletin (Applicability: As specified in the requirement document).  \n- Maintenance organisations or engineers who perform the inspections and corrective actions required by the Boeing service bulletin.\n\n### Why it matters (stated source rationale and mechanical effect)\n\n- The directive responds to an identified hazard: Boeing reported that a fire in the No. 2 engine strut of a Boeing 747-400 was linked to a hole in the No. 2 strut fuel tube caused by electrical arcing from chafing between the fuel tube and an electrical power feeder cable (Background: Boeing have advised that a fire ... attributed to a hole ... caused by electrical arcing resulting from chafing between the fuel tube and the electrical power feeder cable). The AD uses the Boeing service bulletin as the required method to inspect for and correct that condition (Requirement: Action in accordance with Boeing SB 747-24A2168 R1).\n\n### Practical mechanics, incentives and trade-offs\n\n- Who pays: aircraft operators bear the direct costs of inspections and any corrective work required by the Boeing service bulletin (Compliance sections; Requirement section).  \n- Who decides technical detail: the FAA/US manufacturer service bulletin (Boeing SB 747-24A2168 R1) is specified as the method for inspection and repair; the AD requires compliance with that document rather than specifying technical actions itself (Requirement: Action in accordance with Boeing SB 747-24A2168 R1).  \n- Timing and compliance structure: the directive imposes near-term mandatory inspections (Phase 1) and a one‑off corrective action (Phase 2) that, if completed, stops the need for repetitive inspections (Compliance: Phase 1 and Phase 2 notes).  \n- Compliance burden and implementation risk: operators must identify which aeroplanes the service bulletin applies to (Applicability: As specified in the requirement document) and schedule inspections by the prescribed dates. Relying on an external service bulletin means technical compliance depends on the detail and clarity of that document and on operators' interpretation of “as specified” applicability (Requirement; Applicability).  \n- Effects on private choice and market behaviour: operators may reallocate maintenance hours, potentially prioritising this work over other tasks to meet the AD deadlines. Maintenance providers (in-house or third-party) must perform the inspections/repairs to the Boeing SB standard; this creates a compliance cost that operators will either absorb or pass on via contractual arrangements with customers or leasing parties.  \n- Termination trade-off: completing Phase 2 removes ongoing inspection costs by terminating the repetitive Phase 1 requirement (Compliance: Phase 2 - terminating action). This concentrates near-term work and cost but reduces recurring inspection burden thereafter.  \n- Cross-jurisdiction and harmonisation point: the AD notes an FAA airworthiness directive reference, indicating the action is aligned with or informed by foreign regulator guidance (Note: FAA AD T91-20-51 also refers). This can affect compliance choices for operators who operate under multiple regulatory regimes.\n\n### Implementation considerations and risks\n\n- Determining applicability requires consulting the referenced Boeing service bulletin; the AD text does not enumerate serial numbers or submodels itself (Applicability: As specified in the requirement document).  \n- Inspection intervals after Phase 1 are tied to the results of Phase 1 inspections and the intervals set out in the Boeing service bulletin, so ongoing inspection frequency is conditional on findings (Compliance: Phase 1 ... at intervals specified in Boeing SB 747-24A2168 R1 as determined by the results of the Phase inspection).  \n- Operators must manage the scheduling and resource allocation needed to meet the two phase deadlines and to carry out any corrective work found during inspections (Compliance sections)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-105-engine-strut-power-feeder-fuel-tube-clearance","history":"/api/acts/ad-b747-105-engine-strut-power-feeder-fuel-tube-clearance/history","analysis":"/api/acts/ad-b747-105-engine-strut-power-feeder-fuel-tube-clearance/analysis","conflicts":"/api/acts/ad-b747-105-engine-strut-power-feeder-fuel-tube-clearance/conflicts","importantCases":"/api/acts/ad-b747-105-engine-strut-power-feeder-fuel-tube-clearance/important-cases","documents":"/api/acts/ad-b747-105-engine-strut-power-feeder-fuel-tube-clearance/documents"}}