{"id":"F2006B09516","name":"AD/EMB-120/3 Amdt 1 - Autopilot Disengagement Logic","slug":"ad-emb-120-3-amdt-1-autopilot-disengagement-logic","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54093,"registerId":"commonwealth-F2006B09516-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/EMB-120/3 Amdt 1 - Autopilot Disengagement Logic","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)  \nEmbraer EMB-120 (Brasilia) Series Aeroplanes\n\nAD/EMB-120/3\n\nAmdt 1\n\n  \nAutopilot Disengagement Logic 12/91\n\nApplicability: As detailed in the requirement document.\n\nRequirement: Action in accordance with the technical requirements of Brazilian AD 91-03-02 R2.\n\nCompliance: Parts I and II of the requirement document must be actioned in accordance with the original issue of this AD which required compliance within 300 hours time in service after 2 April 1991, or prior to 13 August 1991. Part III of the requirement document must be complied with prior to 31 December 1991.\n\nBackground: Advice has been received of an elevator trim runaway during descent which caused a deep pitch down of the aeroplane. As a result, the crew experienced great difficulty maintaining control of the aircraft. This AD introduces a modification which will allow the crew to quickly disconnect power from the affected servo motor by disengaging the autopilot when the “AP DISCONNECT” button is activated.\n\nNote: Amendment 1 to this AD is issued to require compliance with Part III of Brazilian AD 91-03-02R2 which was introduced with Revision 2 to the Brazilian AD.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"Yes. Amendment 1 expanded the AD's obligations by requiring compliance with Part III of Brazilian AD 91-03-02 R2, which was introduced in Revision 2 of the Brazilian AD (Note). The original issue already required Parts I and II within the stated 300‑hour/13 August 1991 window; the amendment adds the separate Part III compliance deadline (Compliance: Part III must be complied with prior to 31 December 1991), increasing operator obligations and associated costs."},"complexity_factors":["Cross-reference to a foreign airworthiness directive (Brazilian AD 91-03-02 R2), requiring implementers to follow an external technical document rather than self-contained domestic text (Requirement: \"Action in accordance with the technical requirements of Brazilian AD 91-03-02 R2\").","Staged compliance windows with different deadlines and a time-in-service threshold: Parts I & II required within 300 hours TIS after 2 April 1991 or prior to 13 August 1991; Part III required prior to 31 December 1991 (Compliance paragraph).","Safety-critical avionics modification affecting autopilot servo power-disconnect logic — implementation will require technical maintenance, procedural changes and post-modification checks (Background: modification permits crew to disconnect power by disengaging autopilot).","Regulatory amendment altering scope after the original AD (Note: Amendment 1 adds Part III compliance from Revision 2 of the Brazilian AD), creating potential record-keeping and re-scheduling burdens for operators.","Operational impact on flightcrew procedures and potential training or checklist updates to reflect the new disengagement behaviour (Background: crew action when \"AP DISCONNECT\" button is activated)."],"plain_english_summary":"This airworthiness directive requires operators of Embraer EMB-120 aeroplanes to implement a modification to the autopilot disengagement logic so that pressing the “AP DISCONNECT” button removes power from the affected servo motor. It responds to a reported elevator trim runaway and imposes maintenance and inspection work (per Brazilian AD 91‑03‑02 R2) on aircraft owners/operators, who bear scheduling, parts and labour costs and must meet the specified compliance dates."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is an amendment to an existing Airworthiness Directive. The original AD addressed the autopilot disengagement safety issue. Amendment 1 simply adds compliance with Part III of the referenced Brazilian directive — an incremental expansion to complete the safety fix, not a fundamental shift in scope or purpose. The core intent (fixing the trim runaway/autopilot problem) remains unchanged."},"complexity_factors":["Very short document (under 300 words)","Only 4 defined structural elements (Applicability, Requirement, Compliance, Background)","Single cross-reference to Brazilian AD 91-03-02 R2 (external technical standard)","Simple conditional logic: three distinct compliance deadlines based on which 'Part' of the requirement document applies","No nested exceptions or complex definitional sections","Technical content is delegated entirely to the referenced Brazilian airworthiness directive"],"plain_english_summary":"This AD mandates a modification to Embraer EMB-120 autopilot disconnect circuitry so the AP DISCONNECT button cuts power to the servo motor, preventing elevator trim runaway that can cause sudden, hard pitch-downs. It applies to operators of these aircraft in Australia and imposed near-term compliance deadlines in 1991; the amendment adds an extra Part III requirement not in the original directive."}},"importantCases":[],"_links":{"self":"/api/acts/ad-emb-120-3-amdt-1-autopilot-disengagement-logic","history":"/api/acts/ad-emb-120-3-amdt-1-autopilot-disengagement-logic/history","analysis":"/api/acts/ad-emb-120-3-amdt-1-autopilot-disengagement-logic/analysis","conflicts":"/api/acts/ad-emb-120-3-amdt-1-autopilot-disengagement-logic/conflicts","importantCases":"/api/acts/ad-emb-120-3-amdt-1-autopilot-disengagement-logic/important-cases","documents":"/api/acts/ad-emb-120-3-amdt-1-autopilot-disengagement-logic/documents"}}