{"id":"F2006B09691","name":"AD/F27/124 - MLG Drag Strut Attach Fitting","slug":"ad-f27-124-mlg-drag-strut-attach-fitting","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115845,"registerId":"commonwealth-F2006B09691-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F27/124 - MLG Drag Strut Attach Fitting","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)  \nFokker F27 Series Aeroplanes\n\nAD/F27/124 MLG Drag Strut Attach Fitting 12/91\n\nApplicability: All model F27 with serial numbers listed in the Requirement Document. Requirement: Action in accordance with the Technical Requirements of RLD AD 90-138.\n\nNote: Fokker SB F27/54-47 refers.\n\nCompliance: Unless already accomplished, inspect the MLG drag strut attach fitting prior to accumulating 500 flight cycles from 12 December 1991 or by 1 June 1992, whichever is the earlier. If cracks are found replace the MLG drag strut attachment fitting at the threshold stated in the referenced Service Bulletin.\n\nBackground: This Directive requires a high frequency eddy current inspection of the drag strut actuator attachment lug. Failure of this lug may lead to an inability of the actuator to damp landing gear extension resulting in collapse of the main landing gear. This Directive gives 12 months longer to comply than the RLD AD.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive focused on one specific mechanical component on one aircraft type. It has not expanded beyond its original safety purpose."},"complexity_factors":["Very short document (under 200 words)","Only 1 defined term implicitly referenced ('flight cycles' — flights/takeoff-landing cycles)","Single compliance pathway with clear deadline calculation","No nested exceptions or conditional logic beyond the 'if cracks found' replacement trigger","Cross-references only to external technical documents (RLD AD 90-138, Fokker SB F27/54-47) rather than internal legislative provisions","No interpretation section or definitions clause"],"plain_english_summary":"This is an **Airworthiness Directive** — essentially a mandatory safety order for aircraft owners and operators.\n\n**What it does:**\nOrders inspections of a specific part on Fokker F27 aircraft — the **main landing gear (MLG) drag strut attach fitting**. This is a metal component that helps the landing gear extend and absorb shock during landing.\n\n**Who it affects:**\nOwners and operators of all Fokker F27 model aircraft with specific serial numbers (listed in a separate technical document).\n\n**What must be done:**\n- **Inspect** the drag strut attach fitting using a technique called \"high frequency eddy current\" (a way of detecting cracks in metal without taking the part apart)\n- **When:** Before the aircraft completes 500 flights after 12 December 1991, or by 1 June 1992 — whichever comes first\n- **If cracks are found:** Replace the fitting according to instructions in Fokker Service Bulletin F27/54-47\n\n**Why it matters:**\nIf this metal lug cracks and fails, the landing gear could collapse on landing — a potentially catastrophic safety risk. The Australian regulator (CASA) gave operators 12 months longer to comply than the Dutch authority (RLD) required, showing some flexibility while maintaining safety standards.\n\n**Key terms explained:**\n- **Airworthiness Directive (AD):** A legally enforceable safety notice requiring specific maintenance or inspections\n- **Eddy current inspection:** A non-destructive testing method using electromagnetic fields to find surface cracks\n- **Service Bulletin:** Technical instructions issued by the aircraft manufacturer"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The Directive follows the Technical Requirements of RLD AD 90-138 for inspection and replacement but alters the compliance timetable: it provides operators 12 months longer to comply than the referenced RLD AD. Otherwise the technical scope (HFEC inspection of the drag strut actuator attachment lug and replacement per the Service Bulletin if cracks are found) remains as set out in the referenced documents. (Requirement; Background)"},"complexity_factors":["Technical inspection method specified (high-frequency eddy current) requires specialised equipment and trained personnel (Background).","Applicability limited to aircraft with serial numbers listed in an external Requirement Document, requiring cross-referencing (Applicability).","Technical and replacement details are contained in external documents (RLD AD 90-138 and Fokker Service Bulletin), so operators must coordinate multiple sources (Requirement; Note).","Compliance timing combines a flight-cycle threshold and a calendar deadline (500 flight cycles from 12 December 1991 or by 1 June 1992, whichever is earlier), adding scheduling complexity (Compliance).","Replacement thresholds are set by the referenced Service Bulletin rather than in the Directive itself, creating dependency on external parts and procedures (Requirement)."],"plain_english_summary":"This Airworthiness Directive requires operators of listed Fokker F27 aeroplanes to perform a high‑frequency eddy current (HFEC) inspection of the main landing gear drag‑strut actuator attachment lug by the stated flight‑cycle or calendar deadline (whichever occurs first) and to replace the fitting per the referenced Fokker Service Bulletin if cracks are found. Operators bear inspection and replacement costs; the Directive defers technical thresholds to RLD AD 90‑138 and the Service Bulletin and extends the compliance window by 12 months."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f27-124-mlg-drag-strut-attach-fitting","history":"/api/acts/ad-f27-124-mlg-drag-strut-attach-fitting/history","analysis":"/api/acts/ad-f27-124-mlg-drag-strut-attach-fitting/analysis","conflicts":"/api/acts/ad-f27-124-mlg-drag-strut-attach-fitting/conflicts","importantCases":"/api/acts/ad-f27-124-mlg-drag-strut-attach-fitting/important-cases","documents":"/api/acts/ad-f27-124-mlg-drag-strut-attach-fitting/documents"}}