{"id":"F2006B10563","name":"AD/HS 748/28 - Accessory Gearbox Drive Shaft","slug":"ad-hs-748-28-accessory-gearbox-drive-shaft","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116389,"registerId":"commonwealth-F2006B10563-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.","sortOrder":0},{"sectionNumber":"AD/HS 748/28 Accessory Gearbox Drive Sha","sectionType":"part","heading":"AD/HS 748/28 Accessory Gearbox Drive Shaft 8/2000","content":"# AD/HS 748/28 Accessory Gearbox Drive Shaft 8/2000\n\nApplicability: All HS 748 series aircraft.\n\nRequirement: Grease and inspect accessory gearbox drive shafts in accordance with Dowty Aerospace Wolverhampton Service Bulletin 83-518 dated 6 October 1999.\n\nNote: CAA (UK) AD 002-09-99 refers.\n\nCompliance: Within 50 hours time in service (TIS) from the effective date of this Directive and, thereafter, at intervals of 50 hours TIS.\n\nThis Airworthiness Directive becomes effective on 10 August 2000.\n\nBackground: This Directive is prompted by reports of accessory gearbox drive shaft failures that resulted in combustion chamber damage and subsequent flame break out. These failures have been attributed to inadequate lubrication.\n\n![](image.003.png)  \n\nEugene Paul Holzapfel\n\nDelegate of the Civil Aviation Safety Authority 23 June 2000\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 12 July 2000.","sortOrder":1}],"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":false,"description":"The Directive implements the original safety intent: it mandates lubrication and inspection per Dowty Service Bulletin to correct inadequate-lubrication failures. It does not broaden applicability beyond all HS 748 aircraft, nor add requirements beyond the SB and the specific 50‑hour interval stated in the Directive."},"complexity_factors":["Applicability is narrow but absolute: applies to all HS 748 series aircraft (Applicability).","Mandated recurring short interval maintenance creates operational scheduling and cost burden: initial compliance within 50 hours TIS and thereafter every 50 hours TIS (Compliance).","Reliance on an external technical document for the required procedure: Dowty Aerospace Wolverhampton Service Bulletin 83-518 dated 6 October 1999 (Requirement).","Safety rationale ties to specific failure mode (inadequate lubrication → combustion‑chamber damage), which is technical but narrowly defined (Background).","Legal basis is a standard AD power: subregulation 39.1(1) of CAR 1998 referenced in the preamble.","Cross-reference to another regulator's AD (CAA (UK) AD 002-09-99) creates dependency on overseas determinations (Note).","Issuer is an administrative delegate (CASA delegate), leaving limited scope for discretionary variation by operators other than compliance scheduling (Preamble/signature)."],"plain_english_summary":"This Airworthiness Directive requires operators of all HS 748 series aircraft to grease and inspect accessory gearbox drive shafts in accordance with Dowty Aerospace Wolverhampton Service Bulletin 83‑518 (6 October 1999). The work must be done within 50 hours time in service of the Directive and repeated every 50 hours thereafter. CASA states the action addresses shaft failures from inadequate lubrication that caused combustion‑chamber damage. The directive makes operators responsible for carrying out and funding the specified maintenance and following the external service bulletin's instructions."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"N/A — This is a single-issue safety directive addressing a specific mechanical failure mode. It has not expanded beyond its original purpose of mandating inspection and lubrication of a particular aircraft component."},"complexity_factors":["Very short document (under 300 words)","Only 1 defined term ('TIS' — Time In Service, explained in parentheses)","No cross-references to other legislation beyond a single note about a UK aviation directive","Single, unambiguous requirement with clear compliance deadline","No conditional logic, exceptions, or nested provisions","Straightforward applicability (all aircraft of one specific model series)"],"plain_english_summary":"CASA has issued a mandatory maintenance order for all HS 748 series aeroplanes requiring greasing and inspection of the accessory gearbox drive shafts to prevent lubrication-related failures that can breach the engine and cause fire. Owners, operators and maintenance organisations in Australia must perform an initial check within 50 flight hours after 10 August 2000 and repeat every 50 hours, following Dowty Aerospace Service Bulletin 83-518."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hs-748-28-accessory-gearbox-drive-shaft","history":"/api/acts/ad-hs-748-28-accessory-gearbox-drive-shaft/history","analysis":"/api/acts/ad-hs-748-28-accessory-gearbox-drive-shaft/analysis","conflicts":"/api/acts/ad-hs-748-28-accessory-gearbox-drive-shaft/conflicts","importantCases":"/api/acts/ad-hs-748-28-accessory-gearbox-drive-shaft/important-cases","documents":"/api/acts/ad-hs-748-28-accessory-gearbox-drive-shaft/documents"}}