{"id":"F2006B10100","name":"AD/G164/15 Amdt 1 - Rudder Main Spar","slug":"ad-g164-15-amdt-1-rudder-main-spar","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55599,"registerId":"commonwealth-F2006B10100-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/G164/15 Amdt 1 - Rudder Main Spar","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)  \nSchweizer (Grumman) G-164 (Ag-Cat) Series Aeroplanes\n\nAD/G164/15\n\nAmdt 1\n\n  \nRudder Main Spar 4/94\n\nApplicability: Model G-164 with serial numbers 1 through 400.\n\nModel G-164A with serial numbers 401 through 1674\\. Model G-164B with serial numbers 1B through 79B.\n\nRequirement: 1. Action in accordance with Grumman Service Bulletin 61.\n\n2. Visually inspect the interior and exterior of the rudder main tubular spar for corrosion.\n\nNote: The hole fabricated through the bottom of the rudder fitting during compliance with SB 61, is required to be sealed after the spar is inspected and corrosion inhibited.\n\nCompliance: 1. Unless already accomplished, prior to 30 June 1994.\n\n2. (a) For aircraft operating in a salt water environment:\n\nPrior to 31 March 1995, and thereafter at intervals not to exceed one calendar year.\n\n2. (b) For all other aircraft:\n\nPrior to 31 March 1995, and thereafter at intervals not to exceed three calendar years.\n\nBackground: The manufacturer received reports of significant corrosion on the main tubular spar of the rudder assembly. Amendment 1 is issued to introduce a calendar time compliance in lieu of operating time, a separate compliance for aircraft that are operating in a severe corrosive environment, and an additional internal inspection of the spar for corrosion in response to a local report of a rudder main spar failure that was precipitated by internal corrosion.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2252},"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 1 significantly expanded the original directive by switching from operating time-based compliance to calendar time-based compliance, introducing differentiated inspection intervals for aircraft operating in salt water environments versus other operations, and adding a mandatory internal inspection requirement following a report of rudder main spar failure caused by internal corrosion."},"complexity_factors":["Multiple serial number ranges across three aircraft model variants","Environment-dependent compliance schedules (salt water vs other environments)","Mandatory cross-reference to external technical document (Grumman Service Bulletin 61)","Amendment changes measurement basis from operating hours to calendar time","Conditional sealing requirement tied to inspection completion"],"plain_english_summary":"This directive requires owners/operators of Schweizer (Grumman) Ag‑Cat G‑164/G‑164A/G‑164B aircraft to follow Grumman Service Bulletin 61 to access, visually inspect, and treat corrosion in the rudder’s main spar (including drilling and later sealing an access hole). The initial work and inspection have specific calendar deadlines and must be repeated annually for salt‑water operations or every three years otherwise. It responds to discovered hidden, severe corrosion that once caused a spar failure, replacing flight‑hour limits with time‑based inspections."}},"importantCases":[],"_links":{"self":"/api/acts/ad-g164-15-amdt-1-rudder-main-spar","history":"/api/acts/ad-g164-15-amdt-1-rudder-main-spar/history","analysis":"/api/acts/ad-g164-15-amdt-1-rudder-main-spar/analysis","conflicts":"/api/acts/ad-g164-15-amdt-1-rudder-main-spar/conflicts","importantCases":"/api/acts/ad-g164-15-amdt-1-rudder-main-spar/important-cases","documents":"/api/acts/ad-g164-15-amdt-1-rudder-main-spar/documents"}}