{"id":"F2006B10547","name":"AD/HS 748/13 - Engine Mount Structure W Frame Socket Fittings Inspection Hole","slug":"ad-hs-748-13-engine-mount-structure-w-frame-socket-fittings-inspection-hole","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116357,"registerId":"commonwealth-F2006B10547-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HS 748/13 - Engine Mount Structure W Frame Socket Fittings Inspection Hole","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\n# AD/HS 748/13 Engine Mount Structure “W” Frame\n\nSocket Fittings Inspection Hole\n\nApplicability: All HS748 aircraft.\n\n# 5/95\n\n \n\nRequirement: 1. Perform a detailed visual inspection of the “W” frame socket fitting inspection holes to determine if fasteners have been installed or the inspection holes reworked. Inspect in accordance with Jetstream Preliminary Technical Leaflet (PTL) 501 Issue 2, Para 2.1 Part One.\n\n \n\n2.    With the “W” frame removed, perform a detailed visual inspection of all “W” frame socket fitting inspection holes to determine if fasteners have been installed or the inspection holes reworked. Inspect in accordance with Jetstream PTL 501 Issue 2, Para 2.2 Part Two.\n\n \n\n3.    Magnetic Particle inspect all inspection holes and rework as necessary. Inspect and rework as required in accordance with Jetstream PTL 501 Issue 2, Para 2.3 Part Three.\n\n \n\nNote: CAA(UK) AD 002-09-94 refers.\n\n \n\nCompliance: 1. Inspect in accordance with Requirement 1 before 27 April 1996.\n\n \n\n2.    Inspect in accordance with Requirement 2 before initial installation on an aircraft or at the next “W” frame removal.\n\n \n\n3.    Inspect and rework, if fasteners or reworked inspection holes are found, in accordance with Requirement 3, at next “W” frame removal or before 27 April 1996, whichever occurs first.\n\n \n\nNote: Jetstream PTL 501 Issue 2 is the actioning document for Jetstream Service Bulletin HS748-71-33.\n\n \n\nBackground: Jetstream Customer Bulletin No241C inserted drive screws in the inspection holes.\n\nThe drive screws form sharp grooves in the inspection holes in a highly stressed area. Cracks have been reported in “W” frames and some holes have been reworked in excess of their original diameter.\n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific structural defect identified in service. It has not expanded beyond its original purpose of mandating inspections and repairs for the \"W\" frame socket fitting inspection hole issue."},"complexity_factors":["Short, single-purpose directive (3 requirements only)","Minimal defined terms (relies on external technical document: Jetstream PTL 501 Issue 2)","Simple conditional logic (if fasteners found → then perform magnetic particle inspection)","No nested exceptions or complex cross-referencing within the instrument itself","References to external technical documents (CAA UK AD, Jetstream Service Bulletin) create dependency on outside materials not reproduced here"],"plain_english_summary":"This Airworthiness Directive requires operators of HS 748 aircraft to inspect the \"W\" frame socket fittings that mount the engines after discovery that incorrectly installed drive screws created grooves and led to cracks. Cracked engine mounts risk engine separation in flight.\n\nIf defects or unauthorized fasteners are found, operators must perform magnetic particle inspection and repair as necessary; checks are also required whenever the W‑frame is removed for maintenance."},"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":4,"scope_assessment":{"changed":false,"description":"The directive maintains the original corrective scope: identify and remove inserted drive screws and address over‑reworked inspection holes on HS 748 W‑frames. It applies to all HS 748 aircraft and requires inspections and rework per Jetstream PTL 501 Issue 2 (Requirements 1–3; Note). It does not expand applicability beyond the affected component population nor add new mandated repairs beyond those in the PTL and service bulletin."},"complexity_factors":["Multiple sequential inspection requirements with different triggers and timing (Requirement 1–3; Compliance).","Reliance on an external technical actioning document (Jetstream PTL 501 Issue 2 / Service Bulletin HS748‑71‑33) rather than full procedures in the AD (Note).","Requires non‑destructive testing (magnetic particle inspection) and possible rework, creating technical and labour complexity (Requirement 3).","Operational disruption risk because one inspection set is conditional on W‑frame removal; scheduling affects maintenance planning and aircraft downtime (Requirement 2; Compliance).","Applicability to all HS 748 aircraft increases population affected and aggregate cost (Applicability).","Ambiguity in the scope of \"rework as necessary\" and acceptance criteria is delegated to the PTL, creating limited administrative discretion for maintenance organisations (Requirement 3; Note).","Cross‑reference to CAA(UK) AD introduces dependence on an external regulator's findings and history (Note: CAA(UK) AD 002‑09‑94 refers).","Compliance deadlines (before 27 April 1996 or at next removal) create binary timing obligations that may force early removals or schedule rearrangements (Compliance).","Who pays: owners/operators bear inspection, NDT and rework costs; who decides: authorised maintenance organisations following PTL/SB determine rework scope (Requirements; Note; Compliance)."],"plain_english_summary":"This airworthiness directive requires detailed visual and magnetic‑particle inspections of the engine \"W\"‑frame socket‑fitting inspection holes on all HS 748 aircraft, and rework where drive screws or over‑reworked holes are found, following Jetstream PTL 501 Issue 2 (actioning Service Bulletin HS748‑71‑33). Owners/operators and maintenance organisations must carry out the inspections by the specified dates or at the next W‑frame removal to detect and remove features that can initiate cracks in a highly stressed area."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hs-748-13-engine-mount-structure-w-frame-socket-fittings-inspection-hole","history":"/api/acts/ad-hs-748-13-engine-mount-structure-w-frame-socket-fittings-inspection-hole/history","analysis":"/api/acts/ad-hs-748-13-engine-mount-structure-w-frame-socket-fittings-inspection-hole/analysis","conflicts":"/api/acts/ad-hs-748-13-engine-mount-structure-w-frame-socket-fittings-inspection-hole/conflicts","importantCases":"/api/acts/ad-hs-748-13-engine-mount-structure-w-frame-socket-fittings-inspection-hole/important-cases","documents":"/api/acts/ad-hs-748-13-engine-mount-structure-w-frame-socket-fittings-inspection-hole/documents"}}