{"id":"F2006B02115","name":"AD/AC/56 Amdt 3 - Elevator Control System Bob Weight Installation - Inspection and Modification","slug":"ad-ac-56-amdt-3-elevator-control-system-bob-weight-installation-inspection-and-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41345,"registerId":"commonwealth-F2006B02115-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AC/56 Amdt 3 - Elevator Control System Bob Weight Installation - Inspection and Modification","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/56\n\nAmdt 3\n\n  \n\nElevator Control System Bob Weight Installation \\- Inspection and Modification\n\n  \n3/82\n\nApplicability: Models 500, 500A, 500B, 500S, 500U, 520, 560, 560A, 560E, 560F, 680, 680E,\n\n680F, 680F(P) and 720, S/Nos. 1 to 3323 except those aircraft which have complied with Rockwell International Service Bulletins No. 129 Rev. 4 and No. 136 Rev. 3 dated 26 January 1981 as applicable.\n\nDocument: Gulfstream American Service Information No. SI-176.\n\nNote: Rockwell International SB 179 and FAA AD 75-12-09 Amendment 39-4246 refer.\n\nCompliance: 1. Unless already accomplished, initially inspect within the next 25 hours’ time in service after 8 February 1982, and thereafter at intervals not exceeding 60 hours time in service until modified.\n\n2. Modify within 500 hours’ time in service after 8 February, 1982.\n\nNote: Aircraft certified to comply with AD/AC/56B and AD/AC/58B are deemed to comply with this Directive.\n\nBackground: Cracks have been found in the bob weight side supports of six overseas registered aeroplanes. Effectivity has been extended by aircraft serial number and the requirements of AD/AC/56B and AD/AC/58B have been consolidated into this AD.","sortOrder":0}],"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":3,"scope_assessment":{"changed":true,"description":"Scope was expanded and consolidated: effectivity was extended by aircraft serial number and the requirements of AD/AC/56B and AD/AC/58B were merged into this single directive, increasing the set of affected aircraft and replacing multiple directives with one (Background; Applicability)."},"complexity_factors":["Applicability tied to multiple specific models and a serial number range (Applicability).","Tiered compliance timeline: immediate short‑interval inspection (25 hours), recurring inspections (60 hours) until modification, and a fixed modification deadline (500 hours) (Compliance 1 & 2).","Consolidation of prior directives and service bulletins increases cross‑reference requirements (Background; Note references to SBs and FAA AD).","Operational burden concentrated on aircraft operators and maintenance organisations (inspection frequency and modification costs).","Clear pass/fail airworthiness trigger (cracked bob‑weight supports reported) reduces administrative discretion but raises safety‑critical scheduling pressures (Background)."],"plain_english_summary":"This Airworthiness Directive requires operators of specified Twin Commander aeroplanes (serials 1–3323 unless already modified) to inspect the elevator bob‑weight side supports within 25 flight hours after 8 February 1982, repeat inspections every 60 hours until a permanent modification is fitted, and complete that modification within 500 hours. It consolidates earlier related ADs and service-bulletin requirements.\n\nOperators and maintenance organisations pay for inspections and the modification; the Civil Aviation Safety Authority mandates compliance and record‑keeping. The rule replaces recurring inspection duplication by requiring one tracked modification deadline."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"This amendment consolidates two previous airworthiness directives (AD/AC/56B and AD/AC/58B) into a single directive and extends the applicability to additional aircraft serial numbers. The original scope was narrower; this version broadens coverage while simplifying compliance by merging requirements."},"complexity_factors":["Single, specific mechanical defect addressed (cracked bob weight supports)","Clear applicability criteria (specific models and serial number range with explicit exemptions)","Straightforward compliance timeline (25 hours initial, 60 hours recurring, 500 hours for modification)","Limited cross-references (3 external documents: one service bulletin, one FAA AD, and two previous Australian ADs)","No nested conditional logic or defined terms section","Short document (approximately 200 words)"],"plain_english_summary":"Owners/operators of Twin Commander models (serials 1–3323) must inspect the elevator control “bob weight” and carry out a mandated modification after cracks were found in side supports overseas. The AD requires inspection within 25 flight hours (then every 60 hours until modified) and permanent modification within 500 flight hours to prevent possible loss of elevator control. Aircraft already compliant with the earlier AD/AC/56B or AD/AC/58B are exempt."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ac-56-amdt-3-elevator-control-system-bob-weight-installation-inspection-and-modification","history":"/api/acts/ad-ac-56-amdt-3-elevator-control-system-bob-weight-installation-inspection-and-modification/history","analysis":"/api/acts/ad-ac-56-amdt-3-elevator-control-system-bob-weight-installation-inspection-and-modification/analysis","conflicts":"/api/acts/ad-ac-56-amdt-3-elevator-control-system-bob-weight-installation-inspection-and-modification/conflicts","importantCases":"/api/acts/ad-ac-56-amdt-3-elevator-control-system-bob-weight-installation-inspection-and-modification/important-cases","documents":"/api/acts/ad-ac-56-amdt-3-elevator-control-system-bob-weight-installation-inspection-and-modification/documents"}}