{"id":"F2006B02724","name":"AD/B727/24 Amdt 2 - Inboard Flap Drive Angle Gearbox Housing - Inspection and Modification","slug":"ad-b727-24-amdt-2-inboard-flap-drive-angle-gearbox-housing-inspection-and-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42040,"registerId":"commonwealth-F2006B02724-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/24 Amdt 2 - Inboard Flap Drive Angle Gearbox Housing - Inspection and Modification","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 727 Series Aeroplanes\n\n \n\nAD/B727/24\n\nAmdt 2\n\nApplicability: All models.\n\n\nInboard Flap Drive Angle Gearbox Housing - Inspection and Modification\n\n\n5/67\n\n \n\nDocument: Boeing SB No. 27-84, Rev. 2. Compliance: Forthwith.\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\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 \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This appears to be a routine amendment to a long-standing airworthiness directive. The original 1967 directive addressed a specific mechanical issue with Boeing 727 flap systems, and Amendment 2 likely updates the reference to the manufacturer's service bulletin or compliance timing. There is no indication the scope has expanded beyond the original safety-critical maintenance requirement for this specific aircraft component."},"complexity_factors":["Extremely short document — only substantive content is the applicability statement, document reference, and compliance requirement","No defined terms section — relies entirely on external Boeing Service Bulletin for technical details","No conditional logic or exceptions — blanket applicability to all models with immediate compliance","Single cross-reference to external technical document (Boeing SB 27-84 Rev. 2)","Minimal legislative text — essentially a pointer to manufacturer instructions rather than detailed regulatory prescription"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific maintenance action on Boeing 727 aircraft.\n\n**What it does:**\n- Requires owners and operators of **all Boeing 727 models** to inspect and modify the **inboard flap drive angle gearbox housing** — a mechanical component that helps control the aircraft's flaps (the movable surfaces on the wings that help with takeoff and landing).\n\n**Why it matters:**\n- Flap systems are critical for safe flight operations. A failure in the gearbox housing could impair flap movement, potentially affecting the aircraft's ability to slow down or maintain lift during landing.\n- The directive references **Boeing Service Bulletin 27-84, Revision 2** — this is the manufacturer's official technical instruction for how to perform the inspection and modification.\n\n**Who must comply:**\n- Anyone operating or maintaining a Boeing 727 in Australia must follow this directive **\"forthwith\"** (immediately, without delay).\n\n**Key point:** This is **Amendment 2** of the directive, meaning it has been updated twice since originally issued in 1967 (indicated by \"5/67\" — May 1967). The current version supersedes previous amendments."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The supplied text does not state a change to the instrument's applicability or scope; it presents the requirement as applying to 'All models' and mandates compliance 'Forthwith'. Although the instrument is labelled 'Amdt 2', the provided excerpt does not describe any expansion or narrowing of scope compared with prior text, so no scope change can be identified from the supplied material."},"complexity_factors":["Immediate compliance requirement ('Forthwith') limits operator flexibility and increases operational disruption risk.","Applicability to 'All models' broadens the number of effected aircraft and operators, increasing administrative reach.","Technical compliance depends on an external document (Boeing SB No. 27-84, Rev. 2) that contains the actionable procedures; the AD itself does not set out the steps.","The short text does not state whether alternative compliance methods or exemptions are available, creating potential uncertainty for operators.","Implementation requires technical maintenance work on a flight-control component, which typically involves qualified personnel, parts, and possible aircraft downtime."],"plain_english_summary":"What this instrument does, mechanically\n\n- This is an airworthiness directive (AD) issued under the Civil Aviation Safety Authority schedule for Boeing 727 series aeroplanes titled \"AD/B727/24 Amdt 2\". (Header)\n- It requires an inspection and a modification of the inboard flap drive angle gearbox housing. (Inboard Flap Drive Angle Gearbox Housing - Inspection and Modification)\n- The specific procedures and technical steps to be followed are those in Boeing Service Bulletin No. 27-84, Revision 2. (Document: Boeing SB No. 27-84, Rev. 2)\n- The directive applies to all Boeing 727 models. (Applicability: All models)\n- Compliance is required forthwith — that is, without delay. (Compliance: Forthwith)\n\nWho it affects and who decides\n\n- Aircraft operators and owners of Boeing 727 series aeroplanes are the parties required to act, because the AD places an obligation to carry out the inspection and modification on affected aeroplanes. (Applicability: All models; Compliance: Forthwith)\n- The technical content and steps to be followed are set out in the referenced Boeing service bulletin; the regulator (CASA) has issued the AD mandating that those steps be followed. (Document: Boeing SB No. 27-84, Rev. 2)\n\nWhy it matters (as stated in the document and implied by its operation)\n\n- The text of the AD itself instructs operators to inspect and modify a specific component of the flap system and mandates using a particular manufacturer service bulletin; the directive does not include a separate explanation or quantified rationale in the supplied text. (Document: Boeing SB No. 27-84, Rev. 2)\n- Mechanically, the directive changes operator behaviour by requiring immediate action (inspection and modification) on a component cited by type and location. (Inboard Flap Drive Angle Gearbox Housing - Inspection and Modification; Compliance: Forthwith)\n\nPractical implications, trade-offs and implementation risks\n\n- Cost and who pays: The supplied text requires the work but does not state who funds it; because operators are obliged to comply, they will bear or arrange for the costs of inspection and modification unless another arrangement exists outside the AD. (Applicability: All models; Compliance: Forthwith)\n- Operational impact: \"Forthwith\" reduces scheduling flexibility and may cause aircraft downtime until the inspection and modification specified in Boeing SB 27-84 Rev. 2 are completed. (Compliance: Forthwith; Document: Boeing SB No. 27-84, Rev. 2)\n- Compliance burden and technical dependence: The AD delegates the technical method to the Boeing service bulletin. Operators and maintenance organisations must have access to and follow that external document to demonstrate compliance. (Document: Boeing SB No. 27-84, Rev. 2)\n- Regulatory discretion and alternatives: The AD text supplied does not mention alternative compliance paths, exemptions, or transitional relief; the directive is stated as mandatory with immediate effect. (Compliance: Forthwith)\n\nNet effect in plain terms\n\n- All operators of Boeing 727 airplanes must, without delay, perform the inspection and modification set out in Boeing SB No. 27-84 Rev. 2 on the inboard flap drive angle gearbox housing. The directive moves from regulatory instruction to concrete technical action by referencing a manufacturer's service bulletin and imposing an immediate compliance deadline. (Header; Applicability: All models; Document: Boeing SB No. 27-84, Rev. 2; Compliance: Forthwith)\n\nNotes on source limitations\n\n- The supplied text contains the mandatory instruction and the reference to the service bulletin but does not include technical details, a narrative justification, or cost estimates. Any detailed assessment of safety benefits, expected costs, or alternatives would require examining the referenced Boeing service bulletin and any supporting regulatory analysis which are not included in the supplied text."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-24-amdt-2-inboard-flap-drive-angle-gearbox-housing-inspection-and-modification","history":"/api/acts/ad-b727-24-amdt-2-inboard-flap-drive-angle-gearbox-housing-inspection-and-modification/history","analysis":"/api/acts/ad-b727-24-amdt-2-inboard-flap-drive-angle-gearbox-housing-inspection-and-modification/analysis","conflicts":"/api/acts/ad-b727-24-amdt-2-inboard-flap-drive-angle-gearbox-housing-inspection-and-modification/conflicts","importantCases":"/api/acts/ad-b727-24-amdt-2-inboard-flap-drive-angle-gearbox-housing-inspection-and-modification/important-cases","documents":"/api/acts/ad-b727-24-amdt-2-inboard-flap-drive-angle-gearbox-housing-inspection-and-modification/documents"}}