{"id":"F2006B03278","name":"AD/B75/1 Amdt 2 - Wing Spars","slug":"ad-b75-1-amdt-2-wing-spars","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42715,"registerId":"commonwealth-F2006B03278-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B75/1 Amdt 2 - Wing Spars","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Boeing 75 Series Aeroplanes\n\n \n\n# AD/B75/1\n\nAmdt 2\n\nApplicability: All model 75 series.\n\n# Wing Spars 10/92\n\n \n\nRequirement:  Remove the centre fuel tank and inspect both front and rear spars for cracks, checks, and warping. Defective spars should be replaced or repaired in accordance with US Civil Aeronautics Manual 18. Ascertain that all drain holes are open.\n\n \n\nNote 1. Repeated removal of the tank at each annual inspection is not necessary, if after accomplishment of the items mentioned above, the gap between the fuel tank and the upper surface of the centre section is sealed by doping on grade A fabric tape, or equivalent sealing means, to prevent moisture entering the tank compartment.\n\n \n\nNote 2. FAA AD 50-06-02 refers.\n\n \n\nNote 3. Modification of centre section fabric covering in accordance with Old Aeroplane Company Ltd Drawing No 001, or similar approved scheme will allow inspection without fuel tank removal; if applicable.\n\n \n\nCompliance: At each annual inspection, unless the criteria mentioned in Requirement Note 1 is accomplished.\n\n \n\nThe compliance of the previous issue of this Directive was the period as stated. This amendment is effective from 17 September 1992.\n\nBackground: Country of Origin AD. Amendment 1 was issued to allow approved modification of fabric covering to expedite spar inspections.\n\n \n\nAmendment 2 is issued to align this Directive more specifically with the relevant Country of Origin Directive requirements.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","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":2,"scope_assessment":{"changed":false,"description":"This is Amendment 2 to an existing Airworthiness Directive. The amendments have remained tightly focused on the original purpose: ensuring wing spar integrity on Boeing 75 series aircraft. Amendment 1 added an alternative inspection method; Amendment 2 simply aligned the Australian directive with the US FAA requirements. The scope has not expanded beyond the specific safety issue (wing spar inspection) and aircraft type (Boeing 75 series)."},"complexity_factors":["Very short document (approximately 250 words)","Only 1 defined term implicitly ('Amdt' for Amendment)","No cross-references to other legislation beyond a single reference to FAA AD 50-06-02","Simple conditional logic: annual inspection required unless Note 1 criteria met","Single requirement with three explanatory notes","No nested exceptions or complex definitional sections"],"plain_english_summary":"This CASA Airworthiness Directive orders owners/operators of Boeing (Stearman) 75 biplanes to remove the centre fuel tank, inspect front and rear wing spars for cracks/damage, repair or replace defective spars to US standards, and clear drain holes.  \n\nIt affects vintage aircraft owners, museums and aerobatic operators — preventing catastrophic wing-spar failure. Relief: proper sealing can avoid annual tank removal, and an approved modification permits spar inspection without tank removal."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment does not broaden the AD's operational scope. Earlier amendments (Amendment 1) introduced an approved modification route to ease inspections; Amendment 2 aligns the text more closely with the Country of Origin (FAA) directive rather than expanding the range of aircraft affected or adding new obligations. The directive remains focused on inspection and repair of centre-section spars for Model 75 series aeroplanes (Background)."},"complexity_factors":["Short instrument: single-page AD with a central Requirement and three short Notes","Simple conditional relief: exemption from repeated tank removal if sealing per Note 1 is done","References to three external documents: US Civil Aeronautics Manual 18, FAA AD 50-06-02, Old Aeroplane Company Ltd Drawing No 001","One recurring compliance timing rule (annual inspection) with a clear exception","No extensive definitions, nested exceptions, or multiple parts"],"plain_english_summary":"**What this directive does**\n\n- Applies to: all Boeing Model 75 series aeroplanes.\n- Main action (Requirement): remove the centre fuel tank and inspect the front and rear wing spars for cracks, \"checks\" (small surface cracks), and warping. If a spar is found defective, it must be repaired or replaced following the US Civil Aeronautics Manual 18. Also ensure all drain holes are open. (See section: Requirement.)\n- Alternatives to repeated tank removal: after the inspection, you do not have to remove the tank at every annual inspection if you seal the gap between the tank and the centre section upper surface with doping on grade A fabric tape or an equivalent sealing means to prevent moisture entering the tank compartment (Note 1). A specific modification of the centre-section fabric covering (Old Aeroplane Company Ltd Drawing No 001, or an approved equivalent) will also allow inspections without removing the tank (Note 3).\n- Timing (Compliance): the inspection requirement is at each annual inspection unless the sealing criterion in Note 1 has been satisfied.\n- Cross-references: the directive refers to FAA AD 50-06-02 and the US Civil Aeronautics Manual 18 for methods and standards (Note 2 and Requirement).\n\n**Why the directive exists (official rationale)**\n\n- The directive follows a Country of Origin (USA) airworthiness directive. Its stated purpose is to ensure wing spar integrity by catching cracks, checks or warping that could be caused or hidden by moisture ingress into the centre tank area (Background).\n\n**How it works in practice and who it affects**\n\n- Who pays: aircraft owners/operators bear the costs — labour to remove and reinstall the centre tank, inspection labour, and any repair or replacement parts required for spars.\n- Who decides and does the work: certificated maintenance personnel or organisations perform the inspections and, where necessary, repairs or replacements following the cited US manual; the regulator (Civil Aviation Safety Authority under the AD framework) requires compliance at the annual inspection (see Compliance).\n- Behaviour changes required: crews must remove the centre tank and perform physical inspections unless the owner implements an approved sealing method or fabric modification that permits inspection without tank removal (Notes 1 and 3).\n\n**Costs, incentives, trade-offs and implementation risks**\n\n- Direct costs: one-off or recurring labour and aircraft downtime for tank removal/reinstallation and spar inspections; potential parts and repair costs if defects are found (Requirement).\n- Compliance-reducing options: sealing the gap (Note 1) or carrying out the approved fabric modification (Note 3) reduces repeated labour costs by allowing inspections without tank removal, but each option has an upfront cost and requires correct installation and, for the modification, regulator or design approval.\n- External dependencies: the directive relies on external documents (US Civil Aeronautics Manual 18 and FAA AD 50-06-02). That requires operators to obtain and follow those documents for specific repair standards, adding a dependency on foreign technical material (Requirement; Note 2).\n- Implementation risk: incorrect sealing could fail to keep moisture out or could hide developing defects; repairs done to the wrong standard or by unapproved methods could leave safety gaps. The approved-modification route reduces repeated tank removals but requires that the modification is properly approved and implemented (Note 1; Note 3).\n- Enforcement & verification: compliance is checked at annual inspections; the regulator enforces the AD framework but the practical verification depends on maintenance records and inspections by certificated personnel (Compliance).\n\n**Net practical effect**\n\n- The AD mandates regular inspection of critical wing structure (spars) and gives two practical paths to reduce repeated tank removals: (1) apply a specified sealing method after inspection; or (2) fit an approved fabric modification that permits inspection without tank removal. These options trade recurring labour/downtime for upfront modification or correct sealing work (Note 1; Note 3)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b75-1-amdt-2-wing-spars","history":"/api/acts/ad-b75-1-amdt-2-wing-spars/history","analysis":"/api/acts/ad-b75-1-amdt-2-wing-spars/analysis","conflicts":"/api/acts/ad-b75-1-amdt-2-wing-spars/conflicts","importantCases":"/api/acts/ad-b75-1-amdt-2-wing-spars/important-cases","documents":"/api/acts/ad-b75-1-amdt-2-wing-spars/documents"}}