{"id":"F2006B10546","name":"AD/HS 748/12 - Aileron Control Quadrant Assembly Spindle","slug":"ad-hs-748-12-aileron-control-quadrant-assembly-spindle","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116355,"registerId":"commonwealth-F2006B10546-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HS 748/12 - Aileron Control Quadrant Assembly Spindle","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)  \nBritish Aerospace (Hawker Siddeley) HS 748 Series Aeroplanes\n\nAD/HS 748/12 Aileron Control Quadrant Assembly Spindle 5/95\n\nApplicability: All HS748 aircraft equipped with P/N 1R4583 or 2R4583 Aileron Control Quadrant Spindle assemblies which do not have Modification 6112 incorporated.\n\nRequirement: 1. Inspect the Aileron Quadrant Assembly to confirm that the spigot is intact. Inspect in accordance with British Aerospace Mandatory Service Bulletin (MSB) 27/75 Revision 1, Para 2 Part A.\n\n2. Modify the Aileron Quadrant Assembly by introducing a steel spigot in accordance with British Aerospace MSB 27/75 Revision 1, Para 2 Part C.\n\nNote: CAA (UK) AD 0089 refers.\n\nCompliance: 1. Inspect in accordance with Requirement 1 before 12000 hours time in service or before 7 May 1995 whichever is the later. Re-inspect at intervals not to exceed 30 days until modified in accordance with Requirement 2.\n\n2. Modify in accordance with Requirement 2 before 12000 hours time in service, or within 750 hours time in service after 27 April 1995, or before 27 October 1995 whichever occurs last.\n\nAircraft with more than 20000 hours time in service at the effective date of this AD shall be modified within 400 hours time in service or before 31 July 1995 whichever occurs first.\n\nBackground: An incident has been reported where the lower spigot of the aileron control quadrant spindle had broken off. This could reduce aileron control.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive remains tightly focused on its original safety purpose: addressing a specific mechanical failure mode in a particular aircraft type's flight control system. The scope has not expanded beyond the original incident report concerning broken aileron control quadrant spigots."},"complexity_factors":["Multiple cascading compliance deadlines (3 different date/hour thresholds for general modification, plus a separate stricter deadline for high-time aircraft)","Cross-reference to external technical document (British Aerospace MSB 27/75 Revision 1) without reproducing its contents","Conditional applicability based on part numbers and modification status (Modification 6112)","Nested temporal logic: \"whichever is later\" vs \"whichever occurs last\" vs \"whichever occurs first\" creates subtle but important distinctions in deadlines","Interim inspection requirement (30-day re-inspection cycles) until permanent modification is completed"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of HS 748 aeroplanes fitted with aileron quadrant spindle P/N 1R4583 or 2R4583 (unless Modification 6112 is already installed) to inspect the spigot and replace it with a stronger steel version per BAe MSB 27/75.\n\nDeadlines set interim inspection and recurring checks and require the modification within specified flight-hour windows to prevent loss of aileron 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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD's scope is consistent with its stated safety purpose. It applies only to HS 748 aeroplanes with the specified spindle part numbers that lack Modification 6112 and prescribes inspection and a steel-spigot modification per MSB 27/75 to mitigate the risk from a reported spigot break. It does not broaden applicability beyond those parts or mandate unrelated changes."},"complexity_factors":["Targeted applicability to specific part numbers and exclusion if Modification 6112 is present creates tracking and record-checking work for operators (Applicability).","Mandates both an inspection requirement and a mandatory modification, so compliance involves short-term monitoring and a one-time engineering change (Requirement, Para 1–2).","Multiple overlapping compliance timeframes and thresholds (12000 hours; specific dates; 750 hours after 27 April 1995; special 400-hour/31 July 1995 rule for >20000 hours) increase scheduling complexity (Compliance).","Short re-inspection interval (not to exceed 30 days) until modification imposes recurring operational burden and potential airline downtime (Compliance, Requirement 1).","Reliance on an external document (British Aerospace MSB 27/75 Revision 1, Paras 2 Part A and C) requires access to and interpretation of manufacturer procedures for both inspection and modification (Requirement).","Reference to CAA (UK) AD 0089 indicates interjurisdictional coordination and possible differences in source documents/terminology (Note).","Cost and logistics of fitting a steel spigot (parts availability, maintenance facility capability) fall to aircraft operators and may require engineering sign-off and downtime (Requirement 2; Compliance)."],"plain_english_summary":"This airworthiness directive requires operators of HS 748 aircraft fitted with aileron control quadrant spindles P/N 1R4583 or 2R4583 (unless Modification 6112 is already incorporated) to inspect the spindle spigot and install a steel spigot in accordance with British Aerospace MSB 27/75. It responds to a reported failure of the lower spigot that could reduce aileron control.\n\nCASA sets staged compliance dates and inspection intervals; aircraft operators bear inspection and modification costs, must schedule inspections every 30 days until modified, and may face accelerated deadlines if the aircraft has high hours."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hs-748-12-aileron-control-quadrant-assembly-spindle","history":"/api/acts/ad-hs-748-12-aileron-control-quadrant-assembly-spindle/history","analysis":"/api/acts/ad-hs-748-12-aileron-control-quadrant-assembly-spindle/analysis","conflicts":"/api/acts/ad-hs-748-12-aileron-control-quadrant-assembly-spindle/conflicts","importantCases":"/api/acts/ad-hs-748-12-aileron-control-quadrant-assembly-spindle/important-cases","documents":"/api/acts/ad-hs-748-12-aileron-control-quadrant-assembly-spindle/documents"}}