{"id":"F2006B02143","name":"AD/AC/82 - Engine Isolator Assembly- Inspection and/or Replacement","slug":"ad-ac-82-engine-isolator-assembly-inspection-and-or-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41373,"registerId":"commonwealth-F2006B02143-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AC/82 - Engine Isolator Assembly- Inspection and/or Replacement","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/82 Engine Isolator Assembly- Inspection\n\nand/or Replacement\n\n  \n8/84\n\nApplicability: 1. Models 690 and 690A, with S/Nos. 11001 to 11284 which have had engine isolator assemblies replaced after 28 July 1975.\n\n2. Model 690A with S/Nos. 11285 to 11344, Model 690B with S/Nos. 11350 to 11566, Model 690C with S/Nos. 11600 to 11732, Model 690D with S/Nos. 15001 to 15033 and 15037, Model 695 with S/Nos. 95000 to 95084 & Model 695A with S/Nos. 96001 to 96061, 96063 to 96072, 96075, 96078, 96085 and 96088.\n\nRequirement: Gulfstream Aerospace S.B. No. 201.\n\nCompliance: Within 10 hours’ time in service after 9 July 1984, as detailed in Requirement Document.\n\nBackground: Some Barry Wright Corp. engine isolator assemblies have a manufacturing defect which could prevent proper bolt preload and result in premature fatigue fracture of the isolator assembly thru-bolt.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive limits action to specified Twin Commander models and serial numbers, and to isolator assemblies replaced after 28 July 1975, requiring compliance with Gulfstream S.B. No. 201 within the stated deadline. The text does not indicate any change from that stated scope."},"complexity_factors":["Narrow applicability requiring verification of multiple model and serial-number ranges (Applicability).","Reliance on an external technical document (Gulfstream Aerospace S.B. No. 201) for procedure and acceptance criteria (Requirement).","Very short compliance window — within 10 hours' time in service after 9 July 1984 — which pressures scheduling and logistics (Compliance).","Work may require parts replacement and qualified maintenance personnel, creating variable cost and lead‑time for operators.","Safety‑critical failure mode (thru‑bolt fatigue/fracture) increases inspection/replacement priority but does not specify alternatives or discretionary relief in the AD text (Background)."],"plain_english_summary":"**What it does:** Requires inspection and, if necessary, replacement of engine isolator assemblies on specified Twin Commander models and serial-number ranges, carried out to Gulfstream Aerospace Service Bulletin No. 201 within 10 hours' time in service after 9 July 1984.  \n\n**Who it affects and why it matters:** Aircraft owners/operators of the listed aeroplanes must arrange and pay for the work. The directive responds to a reported Barry Wright manufacturing defect that can prevent proper bolt preload and risk thru-bolt fatigue and fracture."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific manufacturing defect in a specific component. It has not expanded beyond its original purpose of mandating inspection/replacement of defective Barry Wright Corp. engine isolator assemblies on affected Twin Commander aircraft."},"complexity_factors":["Single, specific technical requirement referencing an external document (Gulfstream S.B. No. 201)","Limited applicability — only 7 specific aircraft model variants with defined serial number ranges","Simple compliance deadline (10 hours time in service after a fixed date)","No nested exceptions or conditional logic — straightforward 'if your aircraft is on this list, do this'","Short document — approximately 150 words of substantive content","Single background explanation with clear causal chain (defect → improper preload → fatigue → failure)"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It requires owners and operators of specific **Twin Commander aircraft models** to inspect or replace engine isolator assemblies (rubber/metal mounts that cushion the engine from the airframe).\n\n**Who it affects:**\n- Owners and operators of specific Gulfstream/Rockwell/Aero Commander 690 and 695 series aircraft with particular serial numbers\n- Specifically, those aircraft that had engine isolator assemblies replaced after 28 July 1975, or certain serial number ranges of 690A, 690B, 690C, 690D, 695, and 695A models\n\n**What it requires:**\n- Follow Gulfstream Aerospace Service Bulletin No. 201 (a manufacturer's technical instruction)\n- Complete the inspection and/or replacement within **10 hours of flight time** after 9 July 1984\n\n**Why it matters:**\nSome engine isolator assemblies made by Barry Wright Corp. have a manufacturing defect. This defect could stop bolts from being tightened properly, leading to premature metal fatigue and potential failure of the through-bolt. If the isolator fails, the engine could detach from the wing — a catastrophic safety risk.\n\nThis directive is **mandatory** — compliance is not optional for airworthiness certification."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ac-82-engine-isolator-assembly-inspection-and-or-replacement","history":"/api/acts/ad-ac-82-engine-isolator-assembly-inspection-and-or-replacement/history","analysis":"/api/acts/ad-ac-82-engine-isolator-assembly-inspection-and-or-replacement/analysis","conflicts":"/api/acts/ad-ac-82-engine-isolator-assembly-inspection-and-or-replacement/conflicts","importantCases":"/api/acts/ad-ac-82-engine-isolator-assembly-inspection-and-or-replacement/important-cases","documents":"/api/acts/ad-ac-82-engine-isolator-assembly-inspection-and-or-replacement/documents"}}