{"id":"F2006B10554","name":"AD/HS 748/2 - Aileron Cable Support Block","slug":"ad-hs-748-2-aileron-cable-support-block","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116371,"registerId":"commonwealth-F2006B10554-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HS 748/2 - Aileron Cable Support Block","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 748/2 Aileron Cable Support Block 12/94\n\nApplicability: Model HS748 aircraft prior to constructors number 1760, except constructors numbers 1723 through 1727.\n\n \n\nRequirement: Action in accordance with Jetstream Aircraft Service Bulletin HS748-27-63 Rev 2.\n\n \n\nNote: UK CAA AD 008-05-94 refers.\n\n \n\nCompliance: Prior to 1 May 1995.\n\n \n\nBackground: The UK CAA requires the incorporation of Modification No 4602, which installs a support block to the pressure skin below the aileron cable loop under the crew compartment floor. This action is required to eliminate the possibility of the aileron cable fouling under certain aileron control wheel loading conditions.\n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"The directive changes the configuration of affected HS 748 aircraft by requiring incorporation of Modification No 4602, which installs a support block under the crew compartment floor beneath the aileron cable loop. The Background states this is required to eliminate the possibility of aileron cable fouling under certain control wheel loading conditions, thereby altering the aircraft from its prior configuration. (See \"Background\" and \"Requirement\".)"},"complexity_factors":["Narrow and clearly defined applicability (specific constructor numbers excluded/included) reduces complexity (Applicability).","Single, specific technical action prescribed: incorporate Modification No 4602 by following one manufacturer service bulletin (Requirement; Background).","Fixed compliance deadline (prior to 1 May 1995) creates scheduling constraint but not procedural ambiguity (Compliance).","Reliance on external technical document (Jetstream Aircraft Service Bulletin HS748-27-63 Rev 2) means technical complexity is delegated to the manufacturer document.","Cross-reference to a foreign regulator’s AD (UK CAA AD) creates a small coordination factor but does not add procedural options (Note).","Implementation requires licensed maintenance capability and aircraft downtime, which are operational constraints rather than legal complexity (implicit from Requirement and Compliance)."],"plain_english_summary":"This AD, issued by the Civil Aviation Safety Authority, requires fitting a support block beneath the crew-compartment floor on specified British Aerospace HS 748 aeroplanes (certain constructor numbers, excluding 1723–1727) to prevent the aileron cable loop fouling and risking aileron control.  \n\nOperators must have the modification installed per Jetstream Service Bulletin HS748-27-63 Rev 2 before 1 May 1995; owners/operators bear the cost and schedule downtime."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive addressing a specific mechanical defect in a specific aircraft type. It has not expanded beyond its original safety purpose."},"complexity_factors":["Single, specific technical requirement referencing an external service bulletin","Narrow applicability limited to specific constructor number ranges","No defined terms section or interpretive provisions","Simple conditional structure: one requirement, one deadline, one exception","Minimal cross-referencing (only to UK CAA AD and manufacturer service bulletin)","Length: approximately 150 words of substantive content"],"plain_english_summary":"This is an **Airworthiness Directive** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nOrders owners and operators of certain British Aerospace HS 748 aeroplanes to install a support block beneath the cockpit floor. This prevents the aileron control cables (the wires that connect the pilot's control wheel to the wing flaps that steer the plane) from snagging or rubbing against the aircraft's skin during certain flight manoeuvres.\n\n**Who it affects:**\n- Owners and operators of **HS 748 model aircraft** built before constructor number 1760\n- **Except** aircraft with constructor numbers 1723 through 1727 (these are excluded)\n\n**What must be done:**\nFollow the instructions in **Jetstream Aircraft Service Bulletin HS748-27-63 Revision 2** — a technical document from the manufacturer detailing exactly how to install the modification.\n\n**When:**\nBefore 1 May 1995 (this deadline has long passed, meaning compliant aircraft should already have this fix).\n\n**Why it matters:**\nWithout this modification, the aileron cables could foul (catch or jam) under certain control wheel loads. This creates a risk of restricted or jammed roll control — a serious flight safety hazard that could compromise the pilot's ability to bank or level the aircraft."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hs-748-2-aileron-cable-support-block","history":"/api/acts/ad-hs-748-2-aileron-cable-support-block/history","analysis":"/api/acts/ad-hs-748-2-aileron-cable-support-block/analysis","conflicts":"/api/acts/ad-hs-748-2-aileron-cable-support-block/conflicts","importantCases":"/api/acts/ad-hs-748-2-aileron-cable-support-block/important-cases","documents":"/api/acts/ad-hs-748-2-aileron-cable-support-block/documents"}}