{"id":"F2006B02725","name":"AD/B727/25 - Engine Fuel Feed Line B-Nuts - Inspection and Replacement","slug":"ad-b727-25-engine-fuel-feed-line-b-nuts-inspection-and-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42041,"registerId":"commonwealth-F2006B02725-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/25 - Engine Fuel Feed Line B-Nuts - Inspection and Replacement","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/B727/25 Engine Fuel Feed Line B-Nuts - Inspection\n\nand Replacement\n\n\n5/66\n\n \n\nApplicability: All models.\n\n \n\nDocument: Boeing SB No. 28-25, Rev. 1. 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 is a discrete, targeted safety directive focused specifically on B-nuts in fuel feed lines of Boeing 727 aircraft. It has not expanded beyond its original technical scope. The reference to '5/66' suggests this dates from May 1966, indicating it is a historical directive that has remained focused on its original safety purpose without subsequent expansion."},"complexity_factors":["Extremely short document (approximately 100 words of substantive content)","Only 2 defined references (Boeing SB No. 28-25 and the applicability to 'All models')","No cross-references to other legislation or regulations beyond the enabling authority (Civil Aviation Regulations 1998, Part 39)","Simple unconditional directive: single action required, single compliance timeframe ('forthwith')","No exceptions, exemptions, or conditional logic","Standardised AD format with minimal procedural detail (refers out to Boeing technical document for actual implementation steps)"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:** It requires immediate inspection and replacement of specific parts on Boeing 727 aircraft. Specifically, it targets the \"B-nuts\" (a type of threaded fitting) on the engine fuel feed lines. These fittings are critical because they carry fuel to the engines — if they fail, it could cause fuel leaks, engine failure, or fire.\n\n**Who it affects:** Anyone who owns, operates, or maintains Boeing 727 aircraft in Australia (all models are covered).\n\n**What must be done:**\n- **Inspection:** Check the B-nuts on the engine fuel feed lines\n- **Replacement:** Replace them if necessary (per Boeing's instructions)\n- **When:** \"Forthwith\" — meaning immediately, without delay\n- **How:** Follow Boeing Service Bulletin No. 28-25, Revision 1\n\n**Why it matters:** This is a safety-critical fix. Fuel line failures in flight can be catastrophic. The \"forthwith\" compliance means CASA considers this an urgent safety issue that cannot wait for the next scheduled maintenance."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The AD, as supplied, applies to all Boeing 727 models and mandates inspection and replacement actions per Boeing Service Bulletin No. 28-25, Rev. 1 with immediate effect (\"Applicability: All models\"; \"Document: Boeing SB No. 28-25, Rev. 1.\"; \"Compliance: Forthwith\"). The instrument does not indicate any change of scope from a prior instrument within the text provided; it simply sets an immediate mandatory requirement for the stated aircraft and issue."},"complexity_factors":["Immediate compliance requirement (\"Compliance: Forthwith\") increases operational urgency and reduces flexibility.","Applicability covers all Boeing 727 models (\"Applicability: All models\"), widening scope of affected operators.","The AD delegates technical detail to an external document (Boeing SB No. 28-25, Rev. 1), so the AD alone lacks procedural specifics.","Potential logistics and supply issues for replacement parts are not addressed in the AD text.","Enforcement mechanisms and any processes for alternative compliance or exemptions are not set out in the supplied text.","Short, terse drafting means implementation depends on interpretation of the referenced Service Bulletin."],"plain_english_summary":"The Civil Aviation Safety Authority has issued Airworthiness Directive AD/B727/25 requiring immediate inspection and, if needed, replacement of B-nuts on engine fuel feed lines of all Boeing 727 aircraft, to be carried out per Boeing Service Bulletin No. 28‑25, Rev. 1. \n\nThis affects Boeing 727 operators and their maintenance organisations, who must bear the direct costs, downtime and sourcing of parts; the measure aims to address an identified airworthiness/safety concern."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-25-engine-fuel-feed-line-b-nuts-inspection-and-replacement","history":"/api/acts/ad-b727-25-engine-fuel-feed-line-b-nuts-inspection-and-replacement/history","analysis":"/api/acts/ad-b727-25-engine-fuel-feed-line-b-nuts-inspection-and-replacement/analysis","conflicts":"/api/acts/ad-b727-25-engine-fuel-feed-line-b-nuts-inspection-and-replacement/conflicts","importantCases":"/api/acts/ad-b727-25-engine-fuel-feed-line-b-nuts-inspection-and-replacement/important-cases","documents":"/api/acts/ad-b727-25-engine-fuel-feed-line-b-nuts-inspection-and-replacement/documents"}}