{"id":"F2012L00220","name":"AD/DHC-4/1 - Cracking of Upper Engine Mount Brackets","slug":"ad-dhc-4-1-cracking-of-upper-engine-mount-brackets","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":142612,"registerId":"commonwealth-F2012L00220-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Viking Air DHC-4 Series Aeroplanes","sectionType":"division","heading":"Viking Air DHC-4 Series Aeroplanes","content":"### Viking Air DHC-4 Series Aeroplanes\n\n| AD/DHC-4/1 | Cracking of Upper Engine Mount Brackets | 3/2012 |\n| ---------- | --------------------------------------- | ------ |\n\n| Applicability: | All Viking Air (formerly Bombardier Inc.) model DHC-4 and DHC-4A aircraft.                                                                                                                                                                                                        |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Carry out a fluorescent penetrant inspection of upper engine mount bracket assemblies in accordance with Canadian Airworthiness Directive CF-2007-26 dated7 November 2007 or later approved revision.Note: Viking Air Ltd. All Operator Message No. 2007-4-11-02 refers.          |\n| Compliance:    | If the aircraft has an Australian certificate of airworthiness: before further flight after the effective date of this Directive.If the aircraft does not have an Australian certificate of airworthiness: prior to issue of the certificate of airworthiness.                    |\n|                | This Airworthiness Directive becomes effective on 24 February 2012.                                                                                                                                                                                                               |\n| Background:    | A DHC-4 fleet operator discovered that five out of ten aircraft had cracked upper engine mount brackets. As an interim action, this Directive mandates a one-time inspection. Subsequent corrective action may be implemented in the future pending results of the investigation. |\n\n![](image.001.png)\n\nMike Higgins  \nDelegate of the Civil Aviation Safety Authority\n\n8 February 2012","sortOrder":0},{"sectionNumber":"AD/DHC-4/1","sectionType":"part","heading":"AD/DHC-4/1","content":"## AD/DHC-4/1","sortOrder":1},{"sectionNumber":"Cracking of Upper Engine Mount Brackets","sectionType":"part","heading":"Cracking of Upper Engine Mount Brackets","content":"## Cracking of Upper Engine Mount Brackets","sortOrder":2},{"sectionNumber":"3/2012","sectionType":"part","heading":"3/2012","content":"## 3/2012","sortOrder":3}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow Airworthiness Directive targeting a specific safety defect in a specific aircraft type. It has not expanded beyond its original purpose of mandating an interim inspection for cracked engine mount brackets."},"complexity_factors":["Single, specific technical requirement (one inspection type)","Only two compliance scenarios (registered vs unregistered aircraft)","No defined terms section","No cross-references to other legislation (only references Canadian AD and manufacturer message)","Straightforward conditional logic (if/then structure)","Short document (approximately 200 words of substantive content)","Single subject matter (one mechanical component on one aircraft type)"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of Viking Air DHC‑4/DHC‑4A (Caribou) aircraft to perform a one‑time fluorescent dye inspection of the upper engine mount brackets after cracks were found in multiple airframes. \n\nIt applies to all such aircraft for Australian operators and to aircraft before Australian certification, must be done before the next flight after 24 February 2012, and is an interim safety measure pending further action."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The Directive implements a one‑time inspection consistent with the referenced Canadian AD and does not expand or narrow applicability beyond all DHC‑4/DHC‑4A aircraft. It is explicitly framed as an interim action pending investigation, so scope is limited to inspection now with possible later measures."},"complexity_factors":["Single, specified inspection method (fluorescent penetrant) reduces procedural ambiguity","Applicability limited to a defined fleet (all DHC‑4 and DHC‑4A aircraft)","Timing condition tied to certificate status (before further flight vs. before issue of certificate)","Cross‑reference to an external instrument (Canadian AD CF‑2007‑26) requires access to that document","Potential for follow‑on corrective actions pending investigation increases future uncertainty","Regulatory enforcement and effective date are fixed (CASA delegate; effective 24 Feb 2012)"],"plain_english_summary":"This Directive orders a one‑time fluorescent penetrant inspection of the upper engine mount bracket assemblies on all Viking Air (formerly Bombardier) DHC‑4 and DHC‑4A aeroplanes, following Canadian AD CF‑2007‑26 (Requirement). Operators must carry out the inspection before further flight if the aircraft holds an Australian certificate of airworthiness, or before issue of that certificate if it does not (Compliance). The measure is an interim safety check while an investigation continues (Background)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-4-1-cracking-of-upper-engine-mount-brackets","history":"/api/acts/ad-dhc-4-1-cracking-of-upper-engine-mount-brackets/history","analysis":"/api/acts/ad-dhc-4-1-cracking-of-upper-engine-mount-brackets/analysis","conflicts":"/api/acts/ad-dhc-4-1-cracking-of-upper-engine-mount-brackets/conflicts","importantCases":"/api/acts/ad-dhc-4-1-cracking-of-upper-engine-mount-brackets/important-cases","documents":"/api/acts/ad-dhc-4-1-cracking-of-upper-engine-mount-brackets/documents"}}