{"id":"F2006B02145","name":"AD/AC/84 Amdt 1 - Empennage Attachment","slug":"ad-ac-84-amdt-1-empennage-attachment","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41375,"registerId":"commonwealth-F2006B02145-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AC/84 Amdt 1 - Empennage Attachment","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)  \nTwin Commander (Gulfstream/Rockwell/ Aerocommander 500, 600 and 700) Series Aeroplanes\n\nAD/AC/84\n\nAmdt 1\n\n  \nEmpennage Attachment 6/95\n\nApplicability: All models 685, 690 to 690D, 695 to 695B with serial numbers listed in the applicable Requirement Document.\n\nRequirement: 1. For model 695B aircraft, inspect in accordance with Gulfstream Aerospace Service Bulletin (SB) 206.\n\n2. For model 685, 690 to 690D, 695 and 695A aircraft, inspect in accordance with Twin Commander SB 218, Part I.\n\nNote: Twin Commander SB 218 supersedes Gulfstream Aerospace SB 206 for 690 to 690D, 695 and 695A aircraft.\n\nCompliance: For Requirement 1: Inspect before 2000 hours’ time in service. If previously inspected in accordance with the original issue of this Directive, inspect within 12 months or 500 hours’ time in service since the last inspection in accordance with this Directive, whichever occurs first.\n\nRe-inspect at intervals not to exceed 12 months or 500 hours’ time in service whichever occurs first.\n\nFor Requirement 2: Inspect models 690 to 690D, 695 and 695A before 2000 hours’ time in service.\n\nFor model 685, inspect before 2000 hours’ time in service or within 25 hours’ time in service after 25 May 1995, whichever occurs later.\n\nIf previously inspected in accordance with the original issue of this Directive, or Twin Commander SB 218, Part I, inspect within 12 months or 500 hours’ time in service since the last inspection, whichever occurs first.\n\nRe-inspect all models at intervals not to exceed 12 months or 500 hours’ time in service, whichever occurs first, until modified in accordance with Twin Commander SB 218 Part II.\n\nBackground: The manufacturer reports incorrect hardware, loss of torque on the attachment bolts and possible cracking of the tailplane attachment and fin lower ribs. Amendment 1 requires a more intensive inspection for certain model aircraft, includes model 685, and provides for a terminating modification.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"This amendment expanded and intensified the original directive's scope. According to the Background it (1) requires more intensive inspections for certain models, (2) explicitly adds model 685 to the affected population, and (3) introduces a terminating modification (Twin Commander SB 218 Part II) that, once installed, ends the need for recurring inspections. Those changes broaden the set of aircraft covered and add both near‑term inspection obligations and a pathway to eliminate recurring inspections."},"complexity_factors":["Multiple affected models and serial-number limitation (models 685, 690–690D, 695–695B with listed serial numbers)","Two different service bulletins referenced (Gulfstream SB 206 and Twin Commander SB 218 Part I) with a supersession note","Different compliance rules per model (model 685 has a special short-term window; others follow the 2,000-hour rule)","Conditional timing based on prior inspections (if previously inspected under original directive or specified bulletins then next inspection within 12 months or 500 hours)","Recurring inspection requirement until a terminating modification (SB 218 Part II) is completed","Cross-reference to an external Requirement Document for serial numbers (additional cross-document dependency)"],"plain_english_summary":"**What this directive does (mechanics)\n\n- Applies to Twin Commander / Gulfstream / Rockwell Aerocommander models 685, 690–690D, 695–695B listed by serial number in the Requirement Document.  \n- Requires physical inspections of the empennage (tailplane/fin attachment) because the manufacturer found incorrect hardware, bolt torque loss and possible cracking.  \n- Directs operators to follow specific manufacturer Service Bulletins (Gulfstream SB 206 or Twin Commander SB 218, Part I) for how to carry out the inspections.  \n- Sets firm deadlines: inspect before 2,000 hours’ time-in-service for most models; model 685 has an additional near-term window (before 2,000 hours or within 25 hours after 25 May 1995, whichever is later).  \n- If an inspection has already been done under the original directive (or certain earlier bulletins), the next mandatory inspection is within 12 months or 500 flight-hours, whichever comes first.  \n- Requires recurring re‑inspections at intervals not exceeding 12 months or 500 flight‑hours until a specified terminating modification is carried out (Twin Commander SB 218 Part II).\n\nWho is affected\n\n- Aircraft owners and operators of the named Twin Commander / Aerocommander models and serial numbers.  \n- Maintenance organisations and licensed engineers who will perform and certify the inspections and any required repairs or modifications.  \n- The Civil Aviation Safety Authority (CASA) as the regulator enforcing compliance.\n\nWhy it matters (purpose claim and practical implications)\n\n- The manufacturer’s report (recorded in the directive) identifies safety risks: wrong hardware, loss of bolt torque, and possible cracking at the tailplane attachment and fin lower ribs. The directive aims to detect and address those conditions before they cause structural failure (Requirement and Background).  \n- Mechanically, the directive forces regular inspection work and, where necessary, repairs; it also provides a one‑off modification (the terminating action) that, if installed, ends the need for the recurring inspections.\n\nCosts, incentives and trade‑offs (how this changes behaviour)\n\n- Who pays: aircraft owners/operators pay for inspections, any repairs, downtime and the terminating modification if they choose or are required to install it.  \n- Incentives: operators face a trade‑off — pay repeated inspection and repair costs and accept ongoing downtime, or invest in the terminating modification (which is likely more costly up front but stops recurring inspections).  \n- Compliance burden: recurring inspections every 12 months or 500 flight‑hours (whichever first) impose predictable maintenance scheduling and labour costs until the terminating modification is completed (Compliance).  \n- Opportunity cost and market effects: maintenance capacity and parts may be diverted from other work; shops experienced with these models will see increased demand. Larger or more frequent defects concentrate costs on operators of affected serial-numbered aircraft.  \n- Implementation risks: inspections must follow the referenced Service Bulletins (SB 206 or SB 218 Part I); availability of correct hardware, replacement parts or modification kits, plus skilled labour, affects how quickly operators can comply.  \n- Regulatory discretion and enforcement: CASA enforces the directive’s compliance dates; operators choosing to delay the terminating modification remain subject to recurring inspections and oversight.\n\nSummary statement\n\n- This airworthiness directive compels specified Twin Commander / Aerocommander aircraft to be inspected for potential tailplane/fin attachment problems on defined timelines, requires recurrent inspections until a terminating modification is installed, and thereby shifts ongoing inspection and modification costs onto owners/operators while aiming to reduce structural risk. (See Requirements, Compliance and Background.)"},"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":true,"description":"This is Amendment 1 to the original AD/AC/84. The scope has expanded from the original directive to include: (1) model 685 aircraft which were not originally covered, (2) more intensive inspection requirements for certain models, and (3) a terminating modification option (SB 218 Part II) that allows operators to stop the recurring inspection cycle. The original likely only required ongoing inspections without a permanent fix pathway."},"complexity_factors":["Multiple aircraft models with different compliance pathways (695B vs 685/690-690D/695/695A)","Conditional logic based on prior inspection history ('if previously inspected...')","Dual measurement system for recurring inspections (calendar time vs flight hours - 'whichever occurs first')","Cross-references to external technical documents (Service Bulletins 206 and 218) not reproduced in the directive","Different compliance deadlines for initial inspection (model 685 has unique 'whichever occurs later' clause)","Terminating action available (modification per SB 218 Part II) that stops the inspection cycle"],"plain_english_summary":"This directive requires owners/operators of specified Twin Commander (685, 690/690D, 695/695A/695B) aircraft to inspect empennage attachment bolts because incorrect fasteners, loosening, and cracking were found. Initial and recurring inspections follow the manufacturer service bulletins, with re-inspection intervals until a permanent modification is installed. The rule targets preventing in-flight structural failure of the tail that could lead to loss of control and crash."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ac-84-amdt-1-empennage-attachment","history":"/api/acts/ad-ac-84-amdt-1-empennage-attachment/history","analysis":"/api/acts/ad-ac-84-amdt-1-empennage-attachment/analysis","conflicts":"/api/acts/ad-ac-84-amdt-1-empennage-attachment/conflicts","importantCases":"/api/acts/ad-ac-84-amdt-1-empennage-attachment/important-cases","documents":"/api/acts/ad-ac-84-amdt-1-empennage-attachment/documents"}}