{"id":"F2012L01019","name":"AD/DHC-1/12 Amdt 7 - Fatigue Life Limitations","slug":"ad-dhc-1-12-amdt-7-fatigue-life-limitations","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":89362,"registerId":"commonwealth-F2012L01019-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"De Havilland DHC-1 (Chipmunk) Series Aer","sectionType":"division","heading":"De Havilland DHC-1 (Chipmunk) Series Aeroplanes","content":"### De Havilland DHC-1 (Chipmunk) Series Aeroplanes\n\n| AD/DHC-1/12 Amdt 7 | Fatigue Life Limitations | 10/2012 |\n| ------------------ | ------------------------ | ------- |\n\n| Applicability: | All models except English and Portuguese built.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Incorporate into the aircrafts maintenance schedule, life limitations and/or inspections of critical structure determined from a fatigue assessment approved by the Authority.Note 1: The fatigue life assessment may involve retirement lives of components and/or an inspection scheme that manages fatigue through detection of fatigue cracks in critical structure using damage tolerance methodology.Note 2: Consideration should be given to the operational usage and severity of the aircraft’s historical and future operations.                                                                                                                                                                                                                                                                                                         |\n| Compliance:    | This Amendment becomes effective on 14 May 2012.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |\n| Background:    | State of Design Airworthiness Directive G-2012-0001 dated 15 March 2012 has been issued by the UK CAA. The UK directive supersedes requirements for British and Portuguese built aircraft and mandates information contained in TNS CT(C1) No 138 Issue 6 for those aircraft.This Amendment remains applicable to Canadian built Chipmunks and recognises that Canadian built Chipmunks are structurally different to the English and Portuguese built models and in some cases to each other.De Havilland aircraft of Canada have advised that they have not carried out a fatigue assessment of the Canadian Chipmunk models and have no immediate intention to do so. The previous issue of this directive required Canadian Chipmunk models to have a fatigue assessment carried out and this requirement remains unchanged in this directive. |\n\n![](image.001.png)  \nMike Higgins  \nDelegate of the Civil Aviation Safety Authority\n\n8 May 2012","sortOrder":0},{"sectionNumber":"AD/DHC-1/12 Amdt 7","sectionType":"part","heading":"AD/DHC-1/12 Amdt 7","content":"## AD/DHC-1/12 Amdt 7","sortOrder":1},{"sectionNumber":"Fatigue Life Limitations","sectionType":"part","heading":"Fatigue Life Limitations","content":"## Fatigue Life Limitations","sortOrder":2},{"sectionNumber":"10/2012","sectionType":"part","heading":"10/2012","content":"## 10/2012","sortOrder":3}],"analysis":{"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"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This amendment maintains the original scope established in previous versions of the directive. It continues to apply only to Canadian-built Chipmunks and preserves the same fundamental requirement for fatigue assessment. The amendment merely updates the background context to acknowledge a new UK directive covering other manufacturing origins, without expanding the substantive obligations for the Canadian-built aircraft already covered."},"complexity_factors":["Multiple overlapping regulatory regimes (Australian AD, UK CAA directive, Canadian manufacturer position)","Conditional applicability excluding specific manufacturing origins (English and Portuguese built)","Technical aviation terminology requiring domain knowledge (damage tolerance methodology, fatigue assessment, critical structure)","Cross-reference to external technical document (TNS CT(C1) No 138 Issue 6) without full reproduction","Nested conditions in compliance approach (retirement lives OR inspection scheme, with operational usage considerations)","Amendment structure referencing previous versions and their unchanged requirements"],"plain_english_summary":"This AD requires owners/operators of Canadian-built De Havilland DHC‑1 Chipmunk aircraft to impose formal life limits or an approved damage‑tolerance inspection program for fatigue‑susceptible structural parts. It applies only to Canadian-built airframes (not UK or Portuguese-built) because the Canadian manufacturer declined to perform the necessary fatigue assessments. Without those assessments, operators must obtain approval for inspections or replacement limits—or remove affected parts from service—to close a safety gap and prevent possible structural failure."},"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":true,"description":"This amendment narrows operational scope relative to the UK directive by excluding English and Portuguese built Chipmunks (those are governed by the UK CAA directive) while explicitly keeping Canadian‑built Chipmunks subject to the Australian requirement. The previous requirement for Canadian models to have a fatigue assessment remains unchanged; the change is that British/Portuguese builds are now governed by UK material rather than this Amendment (Background; Applicability)."},"complexity_factors":["Technical engineering requirement: fatigue assessment and damage‑tolerance inspection schemes require specialised structural analysis and testing (Requirement).","Regulatory approval: the assessment must be approved by the Authority, introducing discretionary review and potential back‑and‑forth with regulators (Requirement).","Multiple compliance pathways: operators may adopt retirement lives or inspection schemes, creating variability in implementation and recordkeeping (Requirement).","Applicability depends on build origin: English and Portuguese built aircraft are excluded here and covered by UK CAA material, while Canadian built remain subject — requiring identification of airframe origin (Applicability; Background).","Operational-data consideration: assessments must consider historical and future operational usage and severity, increasing data‑collection and analysis burden on operators (Requirement).","Manufacturer position: De Havilland Canada has not performed these assessments and has no immediate intention to do so, shifting practical burden to owners/operators or requiring third‑party work (Background).","Timing: compliance is mandatory from a fixed date, imposing a schedule for assessments, approvals and maintenance‑schedule amendments (Compliance).","Inter-jurisdictional coordination: interplay with UK CAA directive for certain builds may create inconsistency or require cross‑reference to foreign material (Background)."],"plain_english_summary":"This amendment requires operators of De Havilland DHC‑1 (Chipmunk) aeroplanes (excluding English and Portuguese built examples) to put fatigue life limits and/or inspection schemes into their maintenance schedules based on a fatigue assessment approved by the Civil Aviation Safety Authority. Operators must commission or implement either retirement lives or a damage‑tolerance inspection scheme, and comply from 14 May 2012; the rule explicitly keeps Canadian‑built Chipmunks within scope while English/Portuguese‑built aircraft are addressed by a UK CAA directive."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-1-12-amdt-7-fatigue-life-limitations","history":"/api/acts/ad-dhc-1-12-amdt-7-fatigue-life-limitations/history","analysis":"/api/acts/ad-dhc-1-12-amdt-7-fatigue-life-limitations/analysis","conflicts":"/api/acts/ad-dhc-1-12-amdt-7-fatigue-life-limitations/conflicts","importantCases":"/api/acts/ad-dhc-1-12-amdt-7-fatigue-life-limitations/important-cases","documents":"/api/acts/ad-dhc-1-12-amdt-7-fatigue-life-limitations/documents"}}