{"id":"F2006B03409","name":"AD/B767/55 - Centre Fuel Tank Override Pumping Unit Diffuser Assembly","slug":"ad-b767-55-centre-fuel-tank-override-pumping-unit-diffuser-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42950,"registerId":"commonwealth-F2006B03409-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B767/55 - Centre Fuel Tank Override Pumping Unit Diffuser Assembly","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 767 Series Aeroplanes\n\n \n\nAD/B767/55 Centre Fuel Tank Override Pumping\n\nUnit Diffuser Assembly\n\nApplicability: Model 767 line number 1 through 359, 361 and 362. Requirement:  Action in accordance with Boeing Alert SB 767-28A0036.\n\nNote: Sundstrand Alert SB 5006286-28-A4 refers.\n\n \n\nCompliance: Prior to 31 May 1991.\n\n\n7/91\n\nTX\n\n \n\nBackground: On certain S/N override pumping units the brazed joint attaching the diffuser ring to the diffuser sleeve may separate. If this occurred during a dry pump operation an ignition source may occur within the centre tank.\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":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The source text sets a targeted, time-limited requirement for specified Boeing 767 line numbers and delegates corrective action to Boeing Alert SB 767-28A0036. The instrument itself does not indicate any expansion or narrowing beyond that stated applicability and requirement."},"complexity_factors":["Narrow applicability (specific aircraft line numbers listed)","Single operative requirement (follow an external Boeing service bulletin)","Firm, short compliance timeframe (one specified date)","Technical details are delegated to an external document rather than contained in the directive","Minimal procedural or enforcement detail in the text"],"plain_english_summary":"### What this instrument changes mechanically\n\n- It requires operators of certain Boeing 767 aircraft (line numbers 1–359, 361 and 362) to carry out corrective action described in Boeing Alert Service Bulletin 767-28A0036. (Applicability; Requirement)\n- It sets a firm deadline: the required action must be completed prior to 31 May 1991. (Compliance)\n- The directive also points readers to a related Sundstrand Alert SB 5006286-28-A4. (Note)\n\n### Why the directive was issued (official rationale)\n\n- The background states that on certain serial-numbered override pumping units, the brazed joint attaching the diffuser ring to the diffuser sleeve may separate. If that separation happened during a dry pump operation, it could create an ignition source inside the centre fuel tank. The corrective action is required to address that hazard. (Background)\n\n### Practical effects, responsibilities and mechanics of compliance\n\n- The legal text makes compliance conditional on following Boeing Alert SB 767-28A0036. It does not itself describe the technical steps; it delegates the specific corrective work to that service bulletin. (Requirement)\n- The instrument specifies which aircraft are covered by the rule (line numbers listed). That narrows the population of affected aircraft. (Applicability)\n- The directive imposes a time-bound obligation: the work must be done before the stated compliance date. (Compliance)\n- The text refers to an additional manufacturer alert (Sundstrand Alert SB 5006286-28-A4), which operators and maintainers will presumably consult alongside Boeing's bulletin. (Note)\n\n### What the source text says and does not say about costs, discretion and implementation\n\n- The directive requires action by referencing an external service bulletin, but the source text does not allocate who pays for the work, how it will be funded, or who is responsible for scheduling the work. (Requirement; Compliance)\n- The source text does not describe enforcement mechanisms, penalties, or who has discretion to vary the requirement. (Requirement; Compliance)\n- The directive delegates technical content to the Boeing Alert SB; the implementing parties must obtain and follow that bulletin to know exact procedures and parts. The text itself does not give the technical remedy. (Requirement)\n\n### Implementation risks and compliance burden (as indicated by the source)\n\n- The directive creates a time-limited compliance obligation tied to an external technical document. Parties must source and follow that external document to comply. (Requirement; Compliance)\n- The background identifies a clear mechanical failure mode (separation of a brazed joint) and a safety consequence (possible ignition source during dry pump operation). The directive’s stated purpose is to eliminate that specific hazard by the measures in the referenced service bulletin. (Background)\n\n(References: Applicability; Requirement; Note; Compliance; Background.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive issued in 1991 addressing a specific manufacturing defect. It has not evolved or expanded beyond its original purpose of mandating inspection/repair of the centre fuel tank pump diffuser assembly on affected Boeing 767 aircraft."},"complexity_factors":["Single, specific mechanical defect addressed (brazed joint failure in one component)","Only 3 operative paragraphs: applicability, requirement, and compliance deadline","No defined terms section — uses plain technical language","No conditional logic or nested exceptions — straightforward 'do this by this date' structure","Cross-references only to external technical documents (Boeing and Sundstrand service bulletins), not to other legislative provisions","Extremely narrow scope: one aircraft type, specific serial number range, one component"],"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 specific Boeing 767 aeroplanes to inspect or fix a fuel pump problem in the centre fuel tank.\n\n**The safety issue:**\nOn certain aircraft, a brazed joint (a type of metal bonding) in the fuel pump's \"diffuser assembly\" could break apart. If this happened during \"dry pump\" operation (when the pump runs without enough fuel to cool it), it could create sparks — a potential ignition source inside the fuel tank. This is extremely dangerous because fuel vapour plus ignition equals possible explosion.\n\n**Who must act:**\nOwners/operators of Boeing 767s with specific serial numbers — line numbers 1 through 359, plus 361 and 362.\n\n**What they must do:**\nFollow the instructions in **Boeing Alert Service Bulletin 767-28A0036** (a technical repair notice from the manufacturer). There's also a related bulletin from Sundstrand (the pump manufacturer) referenced for additional guidance.\n\n**Deadline:**\nBefore 31 May 1991.\n\n**Why it matters:**\nThis directive prevents potential fuel tank explosions by catching a manufacturing defect before it causes catastrophic failure. Airworthiness Directives are legally binding — ignoring them grounds the aircraft."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b767-55-centre-fuel-tank-override-pumping-unit-diffuser-assembly","history":"/api/acts/ad-b767-55-centre-fuel-tank-override-pumping-unit-diffuser-assembly/history","analysis":"/api/acts/ad-b767-55-centre-fuel-tank-override-pumping-unit-diffuser-assembly/analysis","conflicts":"/api/acts/ad-b767-55-centre-fuel-tank-override-pumping-unit-diffuser-assembly/conflicts","importantCases":"/api/acts/ad-b767-55-centre-fuel-tank-override-pumping-unit-diffuser-assembly/important-cases","documents":"/api/acts/ad-b767-55-centre-fuel-tank-override-pumping-unit-diffuser-assembly/documents"}}