{"id":"F2006B10572","name":"AD/HS 748/7 - Flight Control System Bearing Retaining Rings","slug":"ad-hs-748-7-flight-control-system-bearing-retaining-rings","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116407,"registerId":"commonwealth-F2006B10572-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HS 748/7 - Flight Control System Bearing Retaining Rings","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  British Aerospace (Hawker Siddeley) HS 748 Series Aeroplanes\n\n \n\nAD/HS 748/7 Flight Control System Bearing Retaining Rings 13/94\n\nApplicability: All HS748 aircraft.\n\n \n\nRequirement: Action in accordance with British Aerospace Mandatory Service Bulletin 27/110.\n\n \n\nNote: UK CAA AD 006-03-87 refers.\n\n \n\nCompliance: At the inspection intervals specified in paragraph 2.A and 2.B of the Requirement Document Accomplishment Instructions.\n\n \n\nBackground: The UK CAA requires an on-going check for the security of bearings in housings held in place by Walker Schofield retaining rings.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical component (bearing retaining rings) on a specific aircraft type (HS 748). It has not expanded beyond its original purpose of ensuring flight control system integrity."},"complexity_factors":["Very short document (under 200 words)","Only one substantive requirement: comply with an external technical document (British Aerospace Mandatory Service Bulletin 27/110)","No defined terms section","No conditional logic or nested exceptions","Single cross-reference to UK CAA AD 006-03-87 for background context only","Structure follows standard AD template: Applicability, Requirement, Note, Compliance, Background"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nIt requires owners and operators of **British Aerospace HS 748 series aircraft** to inspect and maintain the flight control system's bearing retaining rings. These are metal rings that hold bearings in place within the aircraft's control mechanisms. If these rings fail, the pilot could lose control of the aircraft.\n\n**Who must follow it:**\nAnyone who owns, operates, or maintains an HS 748 aircraft in Australia.\n\n**What they must do:**\nFollow the instructions in **British Aerospace Mandatory Service Bulletin 27/110** — a technical document from the manufacturer specifying exactly how and when to check these retaining rings. The checks must happen at the time intervals set out in that bulletin.\n\n**Why it matters:**\nThe UK aviation regulator (CAA) identified that **Walker Schofield retaining rings** — a specific type of ring used in these aircraft — could become insecure. This directive ensures Australian operators address the same safety risk that UK regulators flagged. Ignoring it could lead to mechanical failure and loss of aircraft control.\n\n**Key point:** This isn't optional. \"Mandatory Service Bulletin\" and \"Airworthiness Directive\" mean compliance is legally required to keep the aircraft certified to fly."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The directive applies to all HS 748 aircraft and requires action in accordance with British Aerospace Mandatory Service Bulletin 27/110 at the inspection intervals specified in that bulletin (paragraphs 2.A and 2.B). The AD does not expand or narrow the population affected compared with its stated applicability; it leaves operational detail to the referenced service bulletin."},"complexity_factors":["The AD delegates all technical detail (inspection methods and intervals) to an external Mandatory Service Bulletin (British Aerospace MSB 27/110) rather than setting them out in the AD itself (Requirement; Compliance).","The compliance timing is specified only by cross‑reference to paragraphs 2.A and 2.B of the Requirement Document, requiring users to consult another document to determine obligations (Compliance).","Reference to a foreign regulator's AD (UK CAA AD 006-03-87) introduces cross‑jurisdictional dependency for context and justification (Note; Background).","The subject matter is technical (bearing security in flight‑control housings and Walker Schofield retaining rings), requiring specialist maintenance knowledge to interpret and implement (Requirement; Background).","Broad applicability to 'All HS748 aircraft' increases administrative scope for operators, maintenance organisations and the regulator (Applicability)."],"plain_english_summary":"This AD mandates recurring inspections and any corrective work on HS 748 flight‑control bearings retained by Walker Schofield rings, by requiring compliance with British Aerospace Mandatory Service Bulletin 27/110 (see paragraphs 2.A/2.B). It responds to a UK CAA requirement for ongoing checks.\n\nAll HS 748 operators and maintenance organisations must obtain and follow the service bulletin; compliance is regulator‑enforced and will create direct labour, parts, scheduling and downtime costs."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hs-748-7-flight-control-system-bearing-retaining-rings","history":"/api/acts/ad-hs-748-7-flight-control-system-bearing-retaining-rings/history","analysis":"/api/acts/ad-hs-748-7-flight-control-system-bearing-retaining-rings/analysis","conflicts":"/api/acts/ad-hs-748-7-flight-control-system-bearing-retaining-rings/conflicts","importantCases":"/api/acts/ad-hs-748-7-flight-control-system-bearing-retaining-rings/important-cases","documents":"/api/acts/ad-hs-748-7-flight-control-system-bearing-retaining-rings/documents"}}