{"id":"F2006B03037","name":"AD/B747/135 - Potable Water Tank Pressure Relief Valve","slug":"ad-b747-135-potable-water-tank-pressure-relief-valve","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42396,"registerId":"commonwealth-F2006B03037-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/135 - Potable Water Tank Pressure Relief Valve","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 747 Series Aeroplanes\n\n \n\nAD/B747/135 Potable Water Tank Pressure Relief Valve 2/95\n\nApplicability: All Boeing 747 aircraft, line number 1 to 1013 inclusive.\n\n \n\nRequirement: Action in accordance with Boeing Alert Service Bulletin 747-38A2105. Compliance: Unless previously carried out by 1 August 1995.\n\nBackground: Boeing has advised that rupture of several potable water tanks have occurred. In one incident the upper polar cap from the main body of the potable water tank separated and smashed through the cabin floor at seat row 21 striking the main deck ceiling panel and PSU area.\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 addressing a specific mechanical defect in a specific aircraft series. It has not expanded beyond its original purpose of mandating a repair to prevent water tank ruptures."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 1 defined applicability criterion (line numbers 1-1013)","Single compliance action with clear deadline","No cross-references to other legislation or regulations beyond the parent Civil Aviation Regulations 1998","No conditional logic or nested exceptions — straightforward mandatory compliance","References external technical document (Boeing Service Bulletin) rather than embedding complex technical requirements"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:**\nOrders owners and operators of **Boeing 747 aircraft** (specifically those built as line numbers 1 through 1013) to inspect and fix a dangerous problem with the **potable water tank pressure relief valve**.\n\n**The safety problem:**\nBoeing discovered that several drinking water tanks on these planes had ruptured. In one scary incident, the top of a water tank blew off, smashed through the cabin floor near row 21, and damaged the ceiling and passenger service unit (PSU — the panel above your seat with lights and air vents).\n\n**What must be done:**\nOperators must follow the specific repair instructions in **Boeing Alert Service Bulletin 747-38A2105**. This had to be completed by **1 August 1995** unless already done.\n\n**Who it affects:**\nAirlines and operators flying early-model Boeing 747s in Australia.\n\n**Why it matters:**\nThis prevents catastrophic failure of water tanks that could injure passengers, damage critical aircraft systems, or cause decompression at altitude."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD text itself does not indicate any change in scope from a prior instrument. It expressly applies to Boeing 747 aircraft line numbers 1–1013 and requires the actions in Boeing Alert Service Bulletin 747-38A2105 by 1 August 1995 unless already completed (Applicability; Requirement; Compliance). No narrowing or broadening of applicability is stated in this document."},"complexity_factors":["Narrow applicability (only Boeing 747, line numbers 1–1013) reduces breadth of affected parties (Applicability).","Mandatory compliance refers to an external technical document (Boeing Alert Service Bulletin 747-38A2105), so legal text is short but technical execution depends on that external material (Requirement).","Fixed compliance deadline creates operational scheduling pressure but is straightforward to interpret (Compliance).","Safety-critical technical content is delegated to the manufacturer’s Service Bulletin, increasing reliance on technical specialists for implementation.","Background describes a specific failure mode (tank ruptures) but does not provide further technical detail within the AD, leaving diagnosis and remedy to the Service Bulletin."],"plain_english_summary":"CASA mandates that operators of Boeing 747s line numbers 1–1013 carry out the work in Boeing Alert Service Bulletin 747-38A2105 to address reported potable water tank ruptures, with compliance required by 1 August 1995. Operators must obtain the Service Bulletin, schedule and pay for the inspections/modifications, accepting associated downtime and costs to eliminate the identified safety risk."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-135-potable-water-tank-pressure-relief-valve","history":"/api/acts/ad-b747-135-potable-water-tank-pressure-relief-valve/history","analysis":"/api/acts/ad-b747-135-potable-water-tank-pressure-relief-valve/analysis","conflicts":"/api/acts/ad-b747-135-potable-water-tank-pressure-relief-valve/conflicts","importantCases":"/api/acts/ad-b747-135-potable-water-tank-pressure-relief-valve/important-cases","documents":"/api/acts/ad-b747-135-potable-water-tank-pressure-relief-valve/documents"}}