{"id":"F2005L00596","name":"AD/EMB-120/25 Amdt 3 - Nacelle Structure","slug":"ad-emb-120-25-amdt-3-nacelle-structure","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":112853,"registerId":"commonwealth-F2005L00596-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Embraer EMB-120 (Brasilia) Series Aeropl","sectionType":"division","heading":"Embraer EMB-120 (Brasilia) Series Aeroplanes","content":"### Embraer EMB-120 (Brasilia) Series Aeroplanes\n\n| AD/EMB-120/25 Amdt 3 | Nacelle Structure | 4/2005 |\n| -------------------- | ----------------- | ------ |\n\n| Applicability: | Model EMB-120 aircraft with serial numbers 120003, 120004 and 120006 through 120336.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Modify the upper rear nacelle structure in accordance with Embraer Service Bulletin 120-54-0035 Revision 2 or later revision approved by the CTA.Note: CTA AD 97-11-03R2 Amdt 39-1068 refers.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |\n| Compliance:    | Within 2,000 hours time in service after 21 May 1998.The compliance time is unchanged by this issue.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |\n|                | This Amendment becomes effective on 14 April 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |\n| Background:    | The CTA received a report of a fire in the engine exhaust of an aircraft that had suffered an engine failure. The fire penetrated the hydraulic compartment of the nacelle, which resulted in the loss of both hydraulic systems and extensive damage to the nacelle structure. This directive requires the installation of a fire resistant plate to the upper rear nacelle structure.Amendment 1 expanded the applicability and required additional “PART II” action.Amendment 2 was issued in response to a revision of the related CTA AD, which removed from the text of the previous CTA AD, the requirement to replace the exhaust duct rear bracket. Although there was no additional technical requirement, this Directive was amended to reference the latest CTA AD.This amendment is issued to allow the use of later CTA approved revisions of the referenced Embraer service bulletin. |\n\n|     | The original issue of this Airworthiness Directive became effective on 21 May 1998. |\n| --- | ----------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n4 March 2005","sortOrder":0},{"sectionNumber":"AD/EMB-120/25 Amdt 3","sectionType":"part","heading":"AD/EMB-120/25 Amdt 3","content":"## AD/EMB-120/25 Amdt 3","sortOrder":1},{"sectionNumber":"Nacelle Structure","sectionType":"part","heading":"Nacelle Structure","content":"## Nacelle Structure","sortOrder":2},{"sectionNumber":"4/2005","sectionType":"part","heading":"4/2005","content":"## 4/2005","sortOrder":3}],"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":4,"scope_assessment":{"changed":true,"description":"Scope has changed from the original 1998 AD. Amendment 1 expanded applicability and added additional PART II actions; Amendment 2 removed the prior requirement to replace the exhaust duct rear bracket without adding technical measures; Amendment 3 permits use of later CTA‑approved revisions of the referenced Embraer service bulletin. The compliance deadline (2,000 hours after 21 May 1998) remains unchanged."},"complexity_factors":["Serial-numbered applicability restricts the measure to a subset of the fleet and creates tracking/record-keeping needs (Applicability).","Technical action defined by an external service bulletin: Embraer Service Bulletin 120-54-0035 Rev 2 or later CTA‑approved revision — introduces dependency on manufacturer documentation and regulator approval (Requirement).","Historic, fixed compliance window: within 2,000 hours time-in-service after 21 May 1998 — may complicate enforcement and scheduling for operators now (Compliance).","Cross-reference to CTA AD 97-11-03R2 Amdt 39-1068 and allowance for later CTA‑approved revisions increases regulatory cross‑dependency and discretionary approval by CTA (Requirement / Note).","Amendment history creates interpretive complexity: Amendment 1 expanded applicability and added “PART II” action; Amendment 2 removed a previous exhaust-duct rear bracket replacement without adding technical requirements; Amendment 3 permits later CTA-approved service-bulletin revisions (Background / Amendments).","Safety rationale is event-driven (engine-exhaust fire that penetrated the hydraulic compartment) linking the mandated modification to a specific failure mode and consequential system loss (Background).","Effective date and regulatory issuer are specified (effective 14 April 2005; Delegate of CASA), so legal force and administrative ownership are clear (Header / Signature)."],"plain_english_summary":"Requires listed Embraer EMB-120 aeroplanes (serials 120003, 120004, 120006–120336) to have the upper rear nacelle modified by installing a fire‑resistant plate per Embraer Service Bulletin 120‑54‑0035 (Rev 2 or later CTA‑approved). CASA issued the directive after a fire allowed exhaust flames into the hydraulic compartment. Aircraft operators must pay for and schedule the modification within 2,000 flight hours after 21 May 1998 (compliance time unchanged). CTA approval controls which later service‑bulletin revisions are acceptable."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"The legislation maintains its original narrow scope — mandating a specific fire-protection modification for a defined aircraft type. Amendment 3 is purely administrative, expanding only the permissible versions of technical documentation, not the substantive requirements or affected aircraft population."},"complexity_factors":["Single, specific technical requirement (install fire-resistant plate per manufacturer bulletin)","Limited applicability (specific serial number range only)","No nested exceptions or conditional logic — one compliance path only","Minimal cross-referencing (only to manufacturer service bulletin and one related foreign AD)","Short document with clear compliance deadline","Plain language background section explaining the safety rationale"],"plain_english_summary":"This AD requires owners/operators of specified Embraer EMB‑120 Brasilia aircraft to install a fire‑resistant plate in the upper rear nacelle to stop engine exhaust fires from breaching the hydraulic compartment and damaging systems/structure. It applies to the listed serial numbers, retains the original 2,000‑flight‑hour compliance interval from 21 May 1998, and became effective 14 April 2005. Amendment 3 simply permits use of newer manufacturer repair instructions once approved by CASA; no new technical requirements or earlier deadline."}},"importantCases":[],"_links":{"self":"/api/acts/ad-emb-120-25-amdt-3-nacelle-structure","history":"/api/acts/ad-emb-120-25-amdt-3-nacelle-structure/history","analysis":"/api/acts/ad-emb-120-25-amdt-3-nacelle-structure/analysis","conflicts":"/api/acts/ad-emb-120-25-amdt-3-nacelle-structure/conflicts","importantCases":"/api/acts/ad-emb-120-25-amdt-3-nacelle-structure/important-cases","documents":"/api/acts/ad-emb-120-25-amdt-3-nacelle-structure/documents"}}