{"id":"F2006B09512","name":"AD/EMB-120/24 - Aileron Mass Balance Weights","slug":"ad-emb-120-24-aileron-mass-balance-weights","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54081,"registerId":"commonwealth-F2006B09512-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/EMB-120/24 - Aileron Mass Balance Weights","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-120/24 Aileron Mass Balance Weights 5/98\n\nApplicability: All models EMB-120 aircraft.\n\nRequirement: Inspect in accordance with Embraer Service Bulletin 120-27-0077 Revision 01.\n\nNote: CTA AD 98-01-02 Amdt 39-826 refers.\n\nCompliance: For Part I of the Requirement Document:\n\nWithin 150 hours time in service after 23 April 1998, and thereafter at intervals not to exceed 1,000 hours time in service until accomplishment of the inspection required by Part II of the Requirement Document.\n\nFor Part II of the Requirement Document:\n\nWithin 2,000 hours time in service after 23 April 1998 or one calendar year, which ever occurs first.\n\nThis Airworthiness Directive becomes effective on 23 April 1998.\n\nBackground: Investigation has revealed the possibility of a deformation occurring in the mass- balance weights of the aileron, which could eventually lead to a physical contact and possibly friction between the exposed end of the mass-balance weight with the adjoining attach fitting.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow Airworthiness Directive addressing a specific safety-of-flight issue on a single aircraft type. It has not expanded beyond its original purpose of mandating inspections for aileron mass balance weight deformation."},"complexity_factors":["Single, specific mechanical issue (aileron mass balance weights)","Only one defined compliance pathway with two sequential phases (Part I and Part II)","No nested exceptions or conditional logic — straightforward time-based triggers","Cross-reference to only one external document (Embraer Service Bulletin)","Short length (under 300 words)","Clear applicability statement (all EMB-120 models)"],"plain_english_summary":"Owners, operators and maintenance organisations of Embraer EMB-120 (Brasilia) aircraft in Australia must inspect the aileron mass balance weights for deformation and rubbing, following Embraer Service Bulletin 120-27-0077 Rev 01. \n\nAn initial inspection is required within 150 flight hours after 23 April 1998 (then every 1,000 fh until a more detailed check), and a second inspection within 2,000 fh or one year. The AD prevents control-surface issues from bent weights."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Scope remains focused on all EMB‑120 models as stated (Applicability). The directive mandates inspections to detect aileron mass‑balance weight deformation; there is no indication within the text that the applicability or intended target population has been broadened or narrowed from the directive's stated purpose."},"complexity_factors":["Applicability limited to a single aircraft family but covers 'All models EMB‑120' (Applicability) — keeps scope narrow but affects all operators of that type.","External, normative reference to Embraer Service Bulletin 120‑27‑0077 Revision 01 (Requirement) — compliance requires following a separate manufacturer document.","Staged compliance regime with short‑term recurring inspections and a later Part II action (Compliance) — operators must track recurring intervals until the Part II inspection is done.","Specific timing windows (e.g. initial short‑term inspection window and a 2,000‑hour/one‑year deadline for Part II) create scheduling and record‑keeping obligations (Compliance).","Technical nature of the inspection (aileron mass‑balance weight deformation) likely requires maintenance personnel and workshop time; potential repair costs rest with operators (Requirement; Background).","Cross‑reference to another authority document (CTA AD 98‑01‑02 Amdt 39‑826) increases traceability tasks for maintainers (Note).","Effective date specified (becomes effective on 23 April 1998) requires retrospective planning if operators were already in service (Compliance)."],"plain_english_summary":"This Airworthiness Directive requires operators of all Embraer EMB‑120 aircraft to inspect the aileron mass‑balance weights following Embraer Service Bulletin 120‑27‑0077 Rev 01. It imposes specified near‑term and follow‑up inspection timing to detect deformation that might allow the weight to contact adjoining fittings and cause friction. Operators must plan and fund the inspections and any rectification work so the aileron balance remains airworthy."}},"importantCases":[],"_links":{"self":"/api/acts/ad-emb-120-24-aileron-mass-balance-weights","history":"/api/acts/ad-emb-120-24-aileron-mass-balance-weights/history","analysis":"/api/acts/ad-emb-120-24-aileron-mass-balance-weights/analysis","conflicts":"/api/acts/ad-emb-120-24-aileron-mass-balance-weights/conflicts","importantCases":"/api/acts/ad-emb-120-24-aileron-mass-balance-weights/important-cases","documents":"/api/acts/ad-emb-120-24-aileron-mass-balance-weights/documents"}}