{"id":"F2011L01132","name":"AD/DHC-1/25 Amdt 3 - Wing Flaps","slug":"ad-dhc-1-25-amdt-3-wing-flaps","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":86944,"registerId":"commonwealth-F2011L01132-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-1/25 Amdt 3 | Wing Flaps | 13/2011 |\n| ------------------ | ---------- | ------- |\n\n| Applicability: | All English production (C1) all models and Portuguese production (T Mk 20) aircraft.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| Requirement:   | Action in accordance with De Havilland Support TNS CT(C1) No. 166, Issue 5, dated 1 June 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |\n| Compliance:    | At the next annual maintenance check after the effective date of this AD, unless the satisfactory condition of the flap brackets and associated structure is already known. Repeat the inspection at intervals not to exceed 300 flight hours or six years, whichever occurs first.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |\n|                | This Amendment becomes effective on 22 June 2011.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |\n| Background:    | Cracking has been reported in both of the subject flap components. It has been attributed to fatigue induced by repeated use of the footstep on the flap. The Inner Hinge Bracket inspections are unchanged from the previous issues of this Directive. However, the inspection of the Reinforcing Channel was a new requirement introduced in the previous amendment (Amdt 2) of this Directive.This amendment adds the Portuguese manufactured (T Mk 20) to the applicability of the AD. A review has indicated that the inspection is applicable to the Portuguese manufactured model.Amendment 2, effective 27 September 2007, was issued in response to a revision of the requirement document and introduced a compliance of flight hours and calendar time. |\n\n![](image.001.png)  \nGlen Steemson  \nDelegate of the Civil Aviation Safety Authority\n\n17 June 2011","sortOrder":0},{"sectionNumber":"AD/DHC-1/25 Amdt 3","sectionType":"part","heading":"AD/DHC-1/25 Amdt 3","content":"## AD/DHC-1/25 Amdt 3","sortOrder":1},{"sectionNumber":"Wing Flaps","sectionType":"part","heading":"Wing Flaps","content":"## Wing Flaps","sortOrder":2},{"sectionNumber":"13/2011","sectionType":"part","heading":"13/2011","content":"## 13/2011","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":true,"description":"The original AD (prior to Amendment 2) appears to have covered only calendar-time inspections. Amendment 2 introduced flight-hour based compliance (300 hours). This Amendment 3 expands the scope further by adding Portuguese-manufactured T Mk 20 aircraft to the applicability, whereas previous versions apparently covered only English production models. The scope has grown from a UK-centric directive to one covering both major production sources of this aircraft type."},"complexity_factors":["Very short document (approximately 250 words of substantive content)","Only 2 defined applicability categories (English C1 models and Portuguese T Mk 20)","Single primary requirement referencing an external technical document","Simple compliance timeline: next annual check, then repeat every 300 hours/6 years","No nested exceptions or conditional logic — only one exemption (if condition already known)","No cross-references to other legislation or ADs"],"plain_english_summary":"This AD requires owners/operators of De Havilland DHC‑1 Chipmunk (English-built C1 and now Portuguese-built T Mk 20) to inspect the flap inner hinge bracket and reinforcing channel for fatigue cracks caused by using the flap as a footstep. Do the initial check at the next annual after 22 June 2011 (unless already proven sound), then repeat every 300 flight hours or every 6 years, following De Havilland Support TNS CT(C1) No.166 Issue 5 to prevent structural failure."},"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"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"This amendment expands applicability to include Portuguese-manufactured DHC-1 (T Mk 20) aircraft (see 'Applicability'). The core inspection requirement follows De Havilland Support TNS CT(C1) No.166, Issue 5; the reinforcing channel inspection was introduced in Amendment 2 and remains in force, and Amendment 2 also added the flight-hour/calendar compliance regime."},"complexity_factors":["Reference to an external technical document (De Havilland Support TNS CT(C1) No.166, Issue 5) that contains the detailed inspection and repair steps","Conditional compliance language: inspection required ‘at the next annual maintenance unless the satisfactory condition is already known’ (scheduling/verification burden)","Dual repeat interval trigger: inspections repeat at whichever comes first of 300 flight hours or six years (tracking and record-keeping needed)","Applicability spans multiple production origins and models, now including Portuguese-manufactured T Mk 20 (increases number of affected aircraft)","Interaction with prior amendments (Amdt 2 introduced the reinforcing channel inspection and flight-hour/calendar compliance) requires reading amendment history for full scope","Technical nature of work (structural/bracket inspection and possible repair) demands qualified maintenance personnel and spare parts availability"],"plain_english_summary":"Requires owners/operators of English-production De Havilland DHC-1 (C1) models and Portuguese-produced T Mk 20 Chipmunks to inspect flap brackets and related structure following De Havilland Support TNS CT(C1) No. 166, Issue 5. Carry out the inspection at the next annual maintenance (unless condition is already known) and repeat at intervals not exceeding 300 flight hours or six years. Operators bear inspection and repair costs; the AD was issued by CASA and is effective 22 June 2011."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-1-25-amdt-3-wing-flaps","history":"/api/acts/ad-dhc-1-25-amdt-3-wing-flaps/history","analysis":"/api/acts/ad-dhc-1-25-amdt-3-wing-flaps/analysis","conflicts":"/api/acts/ad-dhc-1-25-amdt-3-wing-flaps/conflicts","importantCases":"/api/acts/ad-dhc-1-25-amdt-3-wing-flaps/important-cases","documents":"/api/acts/ad-dhc-1-25-amdt-3-wing-flaps/documents"}}