{"id":"F2007L02658","name":"AD/EMB-120/29 Amdt 4 - Elevator Trim System","slug":"ad-emb-120-29-amdt-4-elevator-trim-system","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":68499,"registerId":"commonwealth-F2007L02658-current","compilationNumber":null,"startDate":"2026-04-02","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-120/29 Amdt 4 | Elevator Trim System | 10/2007 |\n| -------------------- | -------------------- | ------- |\n\n| Applicability: | All Model EMB-120 aircraft.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Action in accordance with the instructions contained in Brazil ANAC AD2001-06-01 R4 Amdt 39-1193.The flight manual amendment required by this Directive is incorporated into the Aircraft Flight Manual at Revision 67, dated 5 June 2001. Once the Flight Manual has been amended to include this revision, the copy of the AD, which ANAC AD2001-06-01 R4 requires to be inserted into the Flight Manual, may be removed.Note: Embraer Service Bulletins 120-25-0262, 120-27-0095, and 120-27-0096, all original issues, or later ANAC approved revisions, refer.                                                                                                                                                                                                                                                                                                       |\n| Compliance:    | As specified in the Requirement document.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |\n|                | This Amendment becomes effective on 27 September 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |\n| Background:    | The occurrence of pitch trim upsets, caused by spring back effect of the elevator trim system control cables, was found to be due to sudden autopilot disengagement during flight descent phase. The problem results from jammed or frozen trim actuators associated with the autopilot trim servo action stretching the cables up to the servo torque limit and consequent release.Amendment 1 required the installation of placards on the cockpit main instrument panel glareshield in addition to the current requirements.Amendment 2 modified the text of the placards on the cockpit main instrument panel glareshield.Amendment 3 was issued to allow the copy of the Brazilian AD which the AD requires to be inserted into the Flight Manual to be removed from the Flight Manual once the Flight Manual has been amended to include the relevant requirements. |\n\n|     | Amendment 4 is issued in response to a revision of the related ANAC AD, which requires modification of the elevator trim system. |\n| --- | -------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nCharles Lenarcic  \nDelegate of the Civil Aviation Safety Authority\n\n17 August 2007","sortOrder":0},{"sectionNumber":"AD/EMB-120/29 Amdt 4","sectionType":"part","heading":"AD/EMB-120/29 Amdt 4","content":"## AD/EMB-120/29 Amdt 4","sortOrder":1},{"sectionNumber":"Elevator Trim System","sectionType":"part","heading":"Elevator Trim System","content":"## Elevator Trim System","sortOrder":2},{"sectionNumber":"10/2007","sectionType":"part","heading":"10/2007","content":"## 10/2007","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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive has remained focused on its original purpose: addressing the elevator trim system safety defect in EMB-120 aircraft. While it has progressed through four amendments, each amendment has refined the remedy rather than expanding the scope — from initial placard requirements (Amendments 1-2), to administrative streamlining (Amendment 3), to the current hardware modification requirement (Amendment 4). The target aircraft, the fundamental safety issue, and the regulatory mechanism have remained consistent."},"complexity_factors":["Short, single-purpose instrument (approximately 400 words)","Only 4 defined/referenced external documents (Brazilian AD, Flight Manual Revision 67, three Service Bulletins)","Simple conditional logic: once Flight Manual updated → remove copy of AD","No nested exceptions or complex cross-referencing within the instrument itself","Heavy reliance on external technical documents (the actual engineering instructions are in the Brazilian AD and Service Bulletins, not reproduced here)","Minimal legislative machinery — no interpretation sections, penalty clauses, or administrative procedures"],"plain_english_summary":"CASA issues a mandatory AD requiring Australian‑registered Embraer EMB‑120 operators to modify the elevator trim system to prevent autopilot disconnects that can produce sudden pitch from control‑cable snap‑back. It adopts Brazil’s ANAC AD2001‑06‑01 R4, requires updating the Aircraft Flight Manual to Revision 67, and compliance with Embraer service bulletins for the hardware changes. This affects all owners, operators, and maintainers of EMB‑120 aircraft in Australia."},"flash_summary":{"complexity_score":7,"scope_assessment":{"changed":true,"description":"Yes. Earlier amendments focused on Flight Manual changes and cockpit placards to mitigate trim upsets (Background; Amendments 1–3). Amendment 4, however, responds to a revision of the related ANAC AD and now requires a modification of the elevator trim system itself, shifting the remedy from procedural/label fixes to a mandated physical modification (Amendment 4; Requirement)."},"complexity_factors":["Cross‑jurisdictional reliance: Mandates action “in accordance with” Brazil ANAC AD2001‑06‑01 R4 Amdt 39‑1193, so compliance depends on an external authority's detailed instructions (Requirement).","Fleet‑wide applicability: Applies to “All Model EMB‑120 aircraft,” creating uniform obligations across every operator of that type (Applicability).","Mix of procedural and hardware remedies: Requires Flight Manual amendment (Revision 67) and, under Amendment 4, a physical modification of the elevator trim system (Requirement; Amendment 4).","Multiple referenced documents: Points to specific Embraer Service Bulletins (120‑25‑0262, 120‑27‑0095, 120‑27‑0096) and the ANAC AD; later ANAC‑approved revisions are acceptable, adding document‑control complexity (Requirement / Note).","Safety‑critical mechanical issue: Root cause described as jammed/frozen trim actuators stretching cables to the servo torque limit and sudden release, implying technical inspection and possible component replacement (Background).","Compliance timing and scope delegated to the referenced documents: The AD states “As specified in the Requirement document,” so precise workscopes, deadlines and acceptance criteria are set outside the directive text (Compliance / Requirement).","Evolution through prior amendments: Earlier Amendments 1–3 imposed placards and Flight Manual insertion/removal rules; Amendment 4 changes the mandated remedy, requiring operators and maintainers to track amendment history (Background).","Operational documentation change management: Requires insertion of Flight Manual Revision 67 and permits later removal of the ANAC AD copy once the FM is updated, creating administrative steps for operators (Requirement).","Implementation cost and logistics: Hardware modification across an entire fleet implies direct maintenance cost, scheduling and potential dispatch downtime (implied by Requirement and Amendment 4)."],"plain_english_summary":"This directive requires all Embraer EMB‑120 aircraft to follow Brazil ANAC AD2001‑06‑01 R4 (Amdt 39‑1193) — including amending the Aircraft Flight Manual (Revision 67) — to fix pitch‑trim upsets caused by elevator trim control‑cable spring‑back and jammed trim actuators. Amendment 4 revises the earlier procedural/placard requirements and now requires a modification of the elevator trim system; operators must comply by following the referenced ANAC AD and Embraer service bulletins."}},"importantCases":[],"_links":{"self":"/api/acts/ad-emb-120-29-amdt-4-elevator-trim-system","history":"/api/acts/ad-emb-120-29-amdt-4-elevator-trim-system/history","analysis":"/api/acts/ad-emb-120-29-amdt-4-elevator-trim-system/analysis","conflicts":"/api/acts/ad-emb-120-29-amdt-4-elevator-trim-system/conflicts","importantCases":"/api/acts/ad-emb-120-29-amdt-4-elevator-trim-system/important-cases","documents":"/api/acts/ad-emb-120-29-amdt-4-elevator-trim-system/documents"}}