{"id":"F2006B03068","name":"AD/B747/166 - Replacement of Hydraulic Fuses","slug":"ad-b747-166-replacement-of-hydraulic-fuses","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42427,"registerId":"commonwealth-F2006B03068-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/166 - Replacement of Hydraulic Fuses","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/B747/166 Replacement of Hydraulic Fuses 2/97\n\nApplicability: Model 747-100, \\-200, \\-300 and SP series aeroplanes, as identified in Boeing Service Letter 747-SL-32-19, dated January 16, 1980, certificated in any category.\n\nRequirement: Waterman hydraulic fuse assemblies part number (P/N) G905-120 are to be replaced with PneuDraulics Hydraulic Fuse Assembly P/N 6105 in accordance with Boeing Service Letter 747-SL-32-19 dated January 16, 1980.\n\nNote: FAA AD 96-22-11 refers.\n\nCompliance: Requirements above are to be completed within 24 months of the effective date of this Directive.\n\nThis Airworthiness Directive becomes effective on 30 January 1997.\n\nBackground: The FAA has received reports of failure of Waterman hydraulic fuses which lead to hydraulic system failures. The fuses failed due to corrosion of the magnesium pistons in the fuses which then failed to close when required. Replacement of the fuses prevents this failure mode and the resultant possibility of reduced controllability of the aircraft through hydraulic system loss.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue safety directive focused specifically on replacing a defective aircraft part. It has not expanded beyond its original purpose of addressing the hydraulic fuse corrosion issue."},"complexity_factors":["Very short document (under 200 words)","Only 1 defined term (P/N for part number)","Single, unambiguous requirement with clear compliance deadline","No cross-references to other legislation sections (only references to Boeing technical document and related FAA directive)","No conditional logic or exceptions","Straightforward applicability criteria based on aircraft model"],"plain_english_summary":"This is a safety order (called an \"Airworthiness Directive\") issued by Australia's aviation safety regulator (CASA) that applies to specific Boeing 747 aircraft models. It requires airlines and aircraft owners to replace a particular type of hydraulic fuse (a safety device that stops fluid leaks in the plane's hydraulic system) with a different, more reliable model. The original Waterman brand fuses have magnesium pistons that can corrode and fail to work when needed, potentially causing complete hydraulic system failure and making the aircraft harder to control. Aircraft operators must complete this replacement within 24 months of January 30, 1997. This directive applies to Boeing 747-100, -200, -300, and SP series planes."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Scope remains focused on replacing a specific fuse P/N on identified Boeing 747 models as set out in the service letter and FAA reports. The Directive implements that corrective substitution with a single, time-limited mandate and does not broaden affected components, aircraft types, or compliance options in the text provided."},"complexity_factors":["Clear, single corrective action (part-for-part replacement) reduces legal complexity.","Applicability limited to specific 747 subtypes and service-letter-identified serials, requiring cross-checking aircraft records.","Fixed 24-month compliance window imposes scheduling and maintenance-planning pressure on operators.","Dependence on availability and procurement of the specified replacement P/N (supply/lead-time risk).","References to external documents (Boeing Service Letter 747-SL-32-19 and FAA AD 96-22-11) require operators to consult additional materials for technical steps.","Safety-critical nature creates oversight and record-keeping obligations under airworthiness regulation.","No discretionary exemptions or alternative-equivalence procedures set out in the directive text — mandatory compliance as written."],"plain_english_summary":"This directive requires operators of specified Boeing 747-100, -200, -300 and SP aeroplanes to replace Waterman hydraulic fuse assemblies (P/N G905-120) with PneuDraulics assemblies (P/N 6105) in accordance with Boeing Service Letter 747-SL-32-19, to be completed within 24 months. CASA issued the directive after FAA reports that corrosion of magnesium pistons allowed fuse failures that can lead to hydraulic system loss. Aircraft operators bear the cost and CASA enforces compliance by law."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-166-replacement-of-hydraulic-fuses","history":"/api/acts/ad-b747-166-replacement-of-hydraulic-fuses/history","analysis":"/api/acts/ad-b747-166-replacement-of-hydraulic-fuses/analysis","conflicts":"/api/acts/ad-b747-166-replacement-of-hydraulic-fuses/conflicts","importantCases":"/api/acts/ad-b747-166-replacement-of-hydraulic-fuses/important-cases","documents":"/api/acts/ad-b747-166-replacement-of-hydraulic-fuses/documents"}}