{"id":"F2006B02185","name":"AD/AC-112/15 - Rudder Spar","slug":"ad-ac-112-15-rudder-spar","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41415,"registerId":"commonwealth-F2006B02185-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AC-112/15 - Rudder 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)  \nGulfstream (Rockwell) 112 Series Aeroplanes\n\nAD/AC-112/15 Rudder Spar 6/95\n\nApplicability: Models 112 and 112B aircraft with serial numbers 13000 and 3 to 544, inclusive.\n\nModels 112TC and 112TCA aircraft with serial numbers 13001 to 13309, inclusive.\n\nRequirement: 1. Visually inspect the rudder spar near the upper hinge fitting for signs of cracking. Check for excessive movement by attempting to move the rudder tip fore and aft and left to right.\n\n2 (a). Remove the rudder assembly from the aircraft as outlined in the Maintenance Manual, Section VII. Remove the rudder tip assembly and the upper hinge fitting. Inspect the forward face of the rudder spar web, bend radius, flanges and angle doublers P/N 44006-RE3, if installed, for cracks in the area of the upper hinge fitting attachment. Inspect using the dye penetrant method in accordance with Rockwell Service Letter SL-112-46 and CAO 108.10.\n\nCracks, including stop drilled cracks, which extend beyond installed angle doublers, P/N 44006-RE3, must be repaired by replacement of the rudder spar before further flight.\n\n2 (b). Modify the rudder spar upper hinge attachment area by installing angle doublers P/N 44006-RE3 in accordance with Rockwell SL-112-46, Figure 1. The rudder spar must be free of cracks before modification.\n\nAny spar with angle doublers installed shall be regarded as cracked unless it can be positively confirmed that the rudder spar was crack free when the angle doublers were installed.\n\nCompliance: 1. Inspect in accordance with Requirement 1 within 10 hours’ time in service after 25 May 1995.\n\n2. Initially inspect in accordance with Requirement 2(a) before 100 hours’ time in service after 25 May 1995. Re-inspect at intervals not to exceed 200 hours’ time in service until modified in accordance with Requirement 2(b).\n\nBackground: The Authority has received reports of cracking of the rudder spar on a model 114 in the region of the upper hinge fitting. Substantial cracking was found on one aircraft 1500 hours’ time in service after compliance with AD/ROCK-114/10 with no defects found. The rudder structure on the model 112 is of similar design. This Directive requires repeat inspections of the hinge fitting area until the rudder spar is modified to the later production standard.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"The directive extends action to Gulfstream (Rockwell) model 112-series aircraft (specified serial numbers) based on service reports of cracking on model 114. In other words, the controller used evidence from a different but similarly designed model to broaden mandatory inspections/modification to the 112 fleet until those aircraft meet the later production standard — (Background)."},"complexity_factors":["Short, tiered compliance windows (inspect within 10 hours; detailed inspection before 100 hours; re-inspect every 200 hours) — (Compliance; Requirement 1; Requirement 2(a)).","Detailed removal and inspection procedure required: remove rudder assembly per Maintenance Manual Section VII; use dye penetrant per Rockwell SL-112-46 and CAO 108.10 — (Requirement 2(a)).","Mandatory repair action: any cracks extending beyond installed angle doublers must be repaired by replacement before further flight, creating immediate grounding and replacement cost — (Requirement 2(a)).","Modification path: install angle doublers P/N 44006-RE3 per Rockwell SL-112-46 as an alternative; installation is conditional on a crack-free spar — (Requirement 2(b)).","Record/verification burden and asymmetry: any spar with angle doublers is 'regarded as cracked' unless there is positive confirmation it was crack-free when doublers were installed, shifting proof burden to operators/maintainers — (Requirement 2(b)).","Applicability limited to specific models and serial-number ranges, narrowing the affected population but requiring serial-level tracking by operators — (Applicability).","Operational and cost impacts borne by aircraft operators: labour and downtime for removal/inspection, potential spar replacement or modification, and ongoing recurrent inspection until modification — (Requirement 1; Requirement 2(a); Requirement 2(b)).","Dependence on external technical documents and manufacturer guidance gives maintenance providers procedural discretion and creates compliance dependency on Rockwell Service Letter SL-112-46 and the Maintenance Manual — (Requirement 2(a); Requirement 2(b))."],"plain_english_summary":"This directive requires operators of specified Gulfstream (Rockwell) 112‑series aeroplanes to inspect the rudder spar near the upper hinge for cracking, to remove and dye‑penetrant inspect the rudder if indicated, and to replace the spar or install angle doublers to the later production standard. Initial inspections must occur within 10–100 flight hours, with repeats every 200 hours until modification. The Authority cites cracking found on a similar model 114 as the trigger."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a single-issue safety directive focused specifically on rudder spar cracking in particular aircraft models. It has not expanded beyond its original purpose of addressing this specific airworthiness concern."},"complexity_factors":["Specific part numbers referenced (P/N 44006-RE3) requiring external manufacturer documentation","Multiple compliance deadlines based on 'time in service' hours rather than calendar dates","Conditional logic: different requirements apply depending on whether angle doublers are already installed","Cross-reference to external documents: Rockwell Service Letter SL-112-46, CAO 108.10, and Maintenance Manual Section VII","Technical aviation terminology throughout (rudder spar, hinge fitting, dye penetrant method, angle doublers)"],"plain_english_summary":"This Airworthiness Directive requires owners/operators of certain Gulfstream (Rockwell) 112-series aeroplanes to inspect and, if necessary, repair or replace the rudder spar and fit reinforcement plates after reports of dangerous cracking near the top hinge. It targets small private/business aircraft to detect hidden damage and prevent rudder failure in flight, averting potential loss of control."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-ac-112-15-rudder-spar","history":"/api/acts/ad-ac-112-15-rudder-spar/history","analysis":"/api/acts/ad-ac-112-15-rudder-spar/analysis","conflicts":"/api/acts/ad-ac-112-15-rudder-spar/conflicts","importantCases":"/api/acts/ad-ac-112-15-rudder-spar/important-cases","documents":"/api/acts/ad-ac-112-15-rudder-spar/documents"}}