{"id":"F2006B02942","name":"AD/B737/43 Amdt 1 - Nacelle Strut Firewall Seal","slug":"ad-b737-43-amdt-1-nacelle-strut-firewall-seal","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42284,"registerId":"commonwealth-F2006B02942-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B737/43 Amdt 1 - Nacelle Strut Firewall Seal","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBoeing 737 Series Aeroplanes\n\nAD/B737/43\n\nAmdt 1\n\n  \nNacelle Strut Firewall Seal 7/92\n\nApplicability: Model 737-300 series with line numbers 1001 through 1485.\n\nRequirement: 1. For aircraft listed in Boeing Service Bulletin 737-54-1028; inspect in accordance with Boeing SB 737-54-1028.\n\n2. For aircraft listed in Boeing SB 737-54-1028 Revision 1, that are not subject to Requirement 1; inspect in accordance with Boeing SB 737-54-1028 Revision 1.\n\nNote: FAA AD 92-07-02 Amdt 39-8198 refers.\n\nCompliance: 1. At the next planned engine removal or within 8,000 hours time in service after 6 September 1990 (the effective date of the initial issue of this Directive).\n\n2. At the next planned engine removal or within 8,000 hours time in service after 25 June 1992, whichever occurs first.\n\nThe compliance of the previous issue of this Directive is as stated in Requirement 1, and is still current for aircraft initially affected. This Amendment is effective from 25 June 1992.\n\nBackground: This Directive was prompted by a manufacturer’s production report that firewall sealant may not have been applied to all the mating surfaces of the engines’ nacelle strut firewall door assemblies. This condition could compromise the integrity of the firewall seal.\n\nAmendment 1 is raised to reflect a revision of the relevant FAA AD, which is prompted by information from the manufacturer which indicates that the firewall sealant apparently was not applied properly during production on additional aircraft.","sortOrder":0}],"analysis":{"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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 1 expanded the affected set of aircraft by incorporating a revision to the Boeing service bulletin and reflecting the revised FAA AD after manufacturer information indicated additional aircraft may have incorrect firewall sealant application, thereby increasing the AD's applicability beyond the initial issue (Amendment 1; Background; Requirement)."},"complexity_factors":["Technical reliance on an external manufacturer service bulletin (Boeing SB 737‑54‑1028 and Revision 1)","Narrow applicability defined by specific aircraft line numbers","Compliance timing tied to operational events (next engine removal) or a flight‑hours threshold (8,000 hours)","Amendment references and aligns with a related FAA AD (inter-jurisdictional coordination)","Practical enforcement and cost burden fall on operators (inspection and any corrective work)"],"plain_english_summary":"This airworthiness directive requires operators of Boeing 737‑300 series aeroplanes (line numbers 1001–1485) to inspect the nacelle strut firewall seal area per Boeing Service Bulletin 737‑54‑1028 (or Revision 1) because sealant may have been omitted or improperly applied, which could compromise the firewall seal (Applicability; Requirement; Background). Operators must carry out inspections at the next planned engine removal or within 8,000 flight hours; they bear inspection and repair costs and CASA enforces compliance (Compliance; Amendment 1)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment slightly expands the scope by capturing additional aircraft discovered to have the same manufacturing defect, but this is a routine technical adjustment consistent with the original safety purpose. The fundamental scope — addressing missing firewall sealant on Boeing 737-300 nacelle struts — remains unchanged."},"complexity_factors":["Very short document (under 300 words)","Only 2 defined applicability criteria (model series and line numbers)","Simple conditional structure: two parallel requirements based on which Boeing Service Bulletin applies","No cross-references to other legislation beyond a single note about the corresponding FAA directive","Clear, single-purpose mandate (inspect and seal) with straightforward compliance deadlines","Minimal defined terms — relies on standard aviation industry terminology"],"plain_english_summary":"This CASA Airworthiness Directive requires operators of Boeing 737-300s (line numbers 1001–1485) to inspect and, if needed, repair missing fireproof firewall sealant in the engine housing per Boeing Service Bulletin 737-54-1028. Action is mandatory at the next engine removal or within 8,000 flight hours (as specified), because omitted sealant could allow an engine fire to breach the firewall. Amendment 1 broadened the AD after more affected aircraft were identified."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-43-amdt-1-nacelle-strut-firewall-seal","history":"/api/acts/ad-b737-43-amdt-1-nacelle-strut-firewall-seal/history","analysis":"/api/acts/ad-b737-43-amdt-1-nacelle-strut-firewall-seal/analysis","conflicts":"/api/acts/ad-b737-43-amdt-1-nacelle-strut-firewall-seal/conflicts","importantCases":"/api/acts/ad-b737-43-amdt-1-nacelle-strut-firewall-seal/important-cases","documents":"/api/acts/ad-b737-43-amdt-1-nacelle-strut-firewall-seal/documents"}}