{"id":"F2006B02860","name":"AD/B737/157 - Oxygen Generators","slug":"ad-b737-157-oxygen-generators","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42202,"registerId":"commonwealth-F2006B02860-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)\n\nBoeing 737 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/B737/157 Oxygen Generators 7/2001 DM","sectionType":"part","heading":"AD/B737/157 Oxygen Generators 7/2001 DM","content":"# AD/B737/157 Oxygen Generators 7/2001 DM\n\nApplicability: Model 737 series aeroplanes, equipped with chemical oxygen generators, as listed in the following Boeing Special Attention Service Bulletins:\n\nB737-35-1076 dated 1 March 2001, and\n\nB737-35-1077 dated 1 March 2001.\n\nRequirement: 1. For airplanes having any chemical oxygen generator and/or passenger, attendant, or lavatory service unit assembly that contains a chemical oxygen generator that has been replaced, carry out a detailed visual inspection of the chemical oxygen generator of the applicable assembly to verify correct installation of the release pin in the generator firing mechanism in accordance with the Accomplishment Instructions of either Service Bulletin (SB) B737-35-1076 or B737-35-1077, as applicable.\n\nNote 1: For the purposes of this Directive, a detailed visual inspection is defined as: \"An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.\"\n\nNote 2: The release pin and safety pin are located in the generator firing mechanism. The safety pin hole is the hole in the generator firing mechanism that is closest to the main body of the generator. The release pin hole is the hole in the generator firing mechanism located furthest from the main body of the generator. The centre axis of the release pin hole is perpendicular to the centre axis of the safety pin hole.\n\nNote 3: Inspections and corrective action carried out before the effective date of this Directive, per Boeing Telex M-7200-00-02474, dated 9, 13, 19, or 31October 2000; or Boeing Telex M-7200-00-03040, dated 18 December 2000; are considered acceptable for compliance with the initial inspection and corrective action specified in Requirement 1. However, prior accomplishment of the inspections and corrective action specified in the telexes does not eliminate the need for the inspection each time an oxygen generator is replaced.","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"This AD remains narrowly focused on correcting an unsafe condition related to the installation of chemical oxygen generators on Boeing 737 series aeroplanes. It requires a specific inspection tied to generator replacement and cross-references Boeing service bulletins and telexes for procedural details. There is no indication in the text provided that the AD expands beyond that original, component-specific safety purpose (no broadened obligations, no added aircraft types, and no general regulatory programme created)."},"complexity_factors":["Narrow, focused subject matter (one aircraft family and one component type) which lowers complexity","Relies on two external Boeing Special Attention Service Bulletins (B737-35-1076 and B737-35-1077) for procedural detail, increasing cross-document referencing","Three explanatory notes that define the inspection standard and pin geometry (Notes 1–3) — few but technically specific definitions","Conditional logic: inspection required when a generator or an assembly containing a generator has been replaced; acceptance of prior telex compliance for initial inspection but continued requirement on each subsequent replacement","No detailed compliance timeframe included in the provided excerpt (the compliance section is referenced but not shown), so timing must be checked in the full AD","Low number of defined terms and short overall length reduce cognitive load"],"plain_english_summary":"**What this instrument does (mechanically)\n\n- **Requires** operators of Boeing 737 series aeroplanes that use chemical oxygen generators to carry out a specific inspection whenever an oxygen generator (or a service unit that contains one) has been replaced. (See: Applicability; Requirement 1.)\n- The inspection is a **detailed visual inspection** to verify that the release pin in the generator firing mechanism is installed in the correct hole, and must be done in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin B737-35-1076 or B737-35-1077, as applicable. (See: Requirement 1 and Boeing SB references.)\n- The AD accepts that inspections and corrective actions already done under certain Boeing telexes (M-7200-00-02474 or M-7200-00-03040) meet the initial inspection requirement, but it does **not** remove the requirement to inspect whenever a generator is replaced in the future. (See: Note 3.)\n- The AD defines what is meant by a \"detailed visual inspection\" (lighting, use of mirrors, possible surface cleaning) and specifies how to identify the release pin hole versus the safety pin hole in the firing mechanism. (See: Notes 1 and 2.)\n\nWho this affects\n\n- Airlines, aircraft operators, and maintenance organisations that operate or service Boeing 737 series aeroplanes equipped with chemical oxygen generators listed in the referenced Boeing service bulletins. (See: Applicability.)\n- Maintenance personnel who perform oxygen-generator replacements and inspections; they must be able to carry out the specified detailed visual inspection and identify the correct pin location. (See: Requirement 1; Notes 1–2.)\n\nWhy it matters (stated purpose and practical implications)\n\n- The AD is issued to correct an unsafe condition related to the installation of chemical oxygen generators: it requires inspection to ensure the release pin is correctly installed so that the generator will operate as intended in an emergency. (This is the safety purpose stated by the issuing delegate; see Requirement 1.)\n\nPractical effects, incentives and costs\n\n- Who pays: operators and maintenance providers bear the direct costs — labour time for the inspection, any corrective action (re-installation or replacement) discovered as a result, and any associated downtime. (See: Requirement 1; Notes.)\n- Who decides: the CASA delegate issues the AD and requires compliance to the Boeing SB instructions; maintenance organisations choose how to schedule and carry out the inspection so long as it follows the referenced SBs and the AD. (See: Applicability; Requirement 1.)\n- Behaviour change: maintenance routines will include the specified check each time the chemical oxygen generator is replaced; inventory and replacement practices may be adjusted to reduce recurrence. (See: Note 3.)\n- Implementation risk and compliance complexity: the AD relies on the operator correctly identifying the release pin hole (Note 2) and executing a \"detailed visual inspection\" as defined (Note 1). Proper lighting, access and possibly minor disassembly or cleaning may be required, which affects maintenance time and access planning. The AD also cross-references Boeing service bulletins and telexes, so compliance requires consulting those external documents. (See: Requirement 1; Notes 1–3.)\n\nTrade-offs and opportunity costs\n\n- The AD trades routine maintenance time and potential short-term operational disruption for a reduced risk that a chemical oxygen generator will fail to operate in an emergency. The benefit is concentrated on passenger safety and the operator's exposure to in-flight emergency risk; the cost is borne by the operator as inspection and corrective-action expense. (See: Requirement 1; Notes.)\n\nNotes and caveats in the legal text\n\n- The AD references two Boeing Special Attention Service Bulletins for the detailed procedures; the AD does not reproduce those procedural steps. Operators must follow the SBs to achieve compliance. (See: Applicability; Requirement 1.)\n- The compliance timing (the precise deadline for when inspections must be completed after the AD becomes effective or after replacement) is referred to in the AD's compliance section, which is not included in the excerpt provided. Operators should consult the full AD text to confirm exact compliance timeframes. (See: general AD structure.)"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific unsafe condition with chemical oxygen generators on Boeing 737s. It has not expanded beyond this safety-critical maintenance requirement."},"complexity_factors":["Short, single-purpose directive focused on one specific mechanical inspection","Only 2 defined technical terms (detailed visual inspection, pin locations) explained in notes rather than a formal definitions section","Clear applicability section limiting scope to specific Boeing 737 models with specific service bulletins","Single requirement with straightforward compliance path (inspect per SB instructions)","One conditional exception (prior telex inspections acceptable for initial compliance but not ongoing)","No cross-references to other legislation beyond subregulation 39.1(1) of CAR 1998 (the enabling power)"],"plain_english_summary":"This CASA Airworthiness Directive requires operators and maintenance personnel on Boeing 737s with specific chemical oxygen generators to perform a detailed visual check of the release pin whenever a generator is replaced. The measure ensures the firing mechanism won’t fail to deliver emergency oxygen—or activate accidentally—protecting passengers and crew. Prior inspections done under Boeing telexes in late 2000 meet the requirement, but the inspection must be repeated every time a generator is replaced going forward."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-157-oxygen-generators","history":"/api/acts/ad-b737-157-oxygen-generators/history","analysis":"/api/acts/ad-b737-157-oxygen-generators/analysis","conflicts":"/api/acts/ad-b737-157-oxygen-generators/conflicts","importantCases":"/api/acts/ad-b737-157-oxygen-generators/important-cases","documents":"/api/acts/ad-b737-157-oxygen-generators/documents"}}