{"id":"F2006B02854","name":"AD/B737/151 - Air Conditioning Duct Insulation","slug":"ad-b737-151-air-conditioning-duct-insulation","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42196,"registerId":"commonwealth-F2006B02854-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.002.png)  \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 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.","sortOrder":0},{"sectionNumber":"AD/B737/151 Air Conditioning Duct Insula","sectionType":"part","heading":"AD/B737/151 Air Conditioning Duct Insulation 4/2001","content":"# AD/B737/151 Air Conditioning Duct Insulation 4/2001\n\nApplicability: Model 737-300, \\-400 and \\-500 series aircraft having the line numbers listed in the requirement document.\n\nRequirement: Rework duct assemblies or replace existing duct assemblies with new or reworked items in accordance with the technical requirements of FAA AD 2000-26-05 Amdt 39-12055.\n\nCompliance: Before 19 April 2007.\n\nThis Airworthiness Directive becomes effective on 19 April 2001.\n\nBackground: An FAA AD has been raised to prevent potential ignition of fibreglass insulation material installed on the outside of the Environmental control system (ECS) ducts, which could propagate a small fire and lead to a larger fire.\n\n![Signature of David Villiers, Delegate of the Civil Aviation Safety Authority.](image.003.png)  \n\nDavid Alan Villiers\n\nDelegate of the Civil Aviation Safety Authority 5 March 2001\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 21 March 2001.","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The AD’s scope aligns with its stated safety purpose: it targets specific 737 variants and line numbers to address ignition risk of external fibreglass insulation and prescribes rework or replacement per FAA technical instructions. There is no indication in the text that the AD expands beyond that original technical safety objective; it instead enforces a time-limited corrective action and delegates compliance oversight to CASA (Applicability; Requirement; Background; Compliance)."},"complexity_factors":["Cross-reference to an external FAA AD (FAA AD 2000-26-05) creates dependency on foreign technical instructions rather than self-contained domestic requirements (Requirement).","Applicability limits the AD to specific Boeing 737-300/-400/-500 line numbers, requiring operators to determine whether individual airframes are affected (Applicability).","Options to either rework or replace duct assemblies introduce technical variation in scope, parts, and labour estimates (Requirement).","Fixed compliance deadline (before 19 April 2007) concentrates workload and supply needs for affected operators (Compliance).","Enforcement rests with CASA under CAR 1998 subregulation 39.1(1) and a named delegate, creating administrative compliance and oversight obligations (opening paragraph; signature).","Safety rationale is narrowly focused on ignition risk of fibreglass insulation, limiting the subject-matter but requiring specific maintenance actions (Background)."],"plain_english_summary":"This Airworthiness Directive requires operators of Boeing 737-300/‑400/‑500 aircraft (specific line numbers listed) to rework or replace external air‑conditioning (ECS) duct assemblies because fibreglass insulation on the ducts could ignite (Applicability; Requirement; Background). The mandated work must follow the technical instructions of FAA AD 2000‑26‑05 and be completed before 19 April 2007. Operators pay for parts and labour, must follow the FAA-specified maintenance method, and comply under CASA’s authority (Compliance; delegate signature)."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope. It addresses a specific safety defect in specific Boeing 737 models and requires a specific remedial action. There is no evidence of scope creep; the directive remains tightly focused on the fire risk from duct insulation in the stated aircraft series."},"complexity_factors":["Very short document (approximately 250 words)","Only 4 defined structural sections (Applicability, Requirement, Compliance, Background)","Single technical reference to external FAA directive rather than detailed technical specifications within the document itself","No nested exceptions or conditional logic - straightforward mandatory action","Clear, fixed compliance deadline with no alternative timelines or escalations","Minimal cross-referencing (only one external reference to FAA AD 2000-26-05)"],"plain_english_summary":"This safety order requires operators of certain Boeing 737-300/400/500 aircraft to repair or replace fibreglass insulation around environmental control system (ECS) ducts to eliminate an ignition risk that can allow a small fire to spread. Compliance follows FAA AD 2000-26-05, affects aircraft listed by serial number, and had to be completed by 19 April 2007 to prevent potentially catastrophic in-flight fires."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-151-air-conditioning-duct-insulation","history":"/api/acts/ad-b737-151-air-conditioning-duct-insulation/history","analysis":"/api/acts/ad-b737-151-air-conditioning-duct-insulation/analysis","conflicts":"/api/acts/ad-b737-151-air-conditioning-duct-insulation/conflicts","importantCases":"/api/acts/ad-b737-151-air-conditioning-duct-insulation/important-cases","documents":"/api/acts/ad-b737-151-air-conditioning-duct-insulation/documents"}}