{"id":"F2011L01119","name":"AD/DHC-1/28 Amdt 10 - Undercarriage Mounting Casting","slug":"ad-dhc-1-28-amdt-10-undercarriage-mounting-casting","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":86919,"registerId":"commonwealth-F2011L01119-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-1/28 Amdt 10 | Undercarriage Mounting Casting | 13/2011 |\n| ------------------- | ------------------------------ | ------- |\n\n| Applicability: | English production (C1), all models, and Portuguese (T Mk 20) production models.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Inspect in accordance with British Aerospace Technical News Sheet CT (C1) No. 165 Issue 7, dated 1 June 2010 or later revision approved by the UK CAA.Wings modified in accordance with De Havilland Mod H.310 may not need further inspection per this AD. Consult the requirement document and contact the TC holder for further information if there is any doubt about your aircrafts status in relation to this modification and the need for continuing inspections.Note 1: UK CAA AD 2807 refers.                                                                                                                                                                                                                                                                                                                                                  |\n| Compliance:    | At the inspection intervals and limits specified in the Requirement document.Prior compliance with this Directive at Amendment 8 constitutes compliance with this amendment.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |\n|                | This Amendment becomes effective on 23 June 2011.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |\n| Background:    | Numerous cases of cracking have been documented in the main undercarriage leg mounting casting in each wing. Inspection of wings returned for overhaul and repair revealed cracking of the undercarriage mounting casting. These cracks are the result of stress corrosion which is related primarily to elapsed calendar time rather than flight hours.This amendment adds the Portuguese manufactured DHC-1 (T Mk 20) to the applicability of this AD. A review has indicated that this inspection is applicable to the Portuguese manufactured T Mk 20 model.There is no change to the requirements or compliance from the previous amendment.Recent amendment history:Amendment 4 relaxed inspection intervals, and introduced suggested examination techniques.Amendment 5, effective 23 May 1996, reflected a variation to re-inspection intervals. |\n|                | Amendment 6, effective on 7 October 1999, amended the mounting casting top and bottom flange inspection limits.Amendment 7, effective 2 December 1999, corrected administrative problems which occurred during processing of Amendment 6.Amendment 8 was issued in response to the latest issue of the Requirement document which reflects the need to defuel the aircraft prior to the inspection.Amendment 9, effective 10 January 2011, was issued to update the requirement document to Issue 7.The original issue of this Airworthiness Directive became effective on 1 April 1979.                                                                                                                                                                                                                                                                  |\n\n![](image.001.png)  \nGlen Steemson  \nDelegate of the Civil Aviation Safety Authority\n\n17 June 2011","sortOrder":0},{"sectionNumber":"AD/DHC-1/28 Amdt 10","sectionType":"part","heading":"AD/DHC-1/28 Amdt 10","content":"## AD/DHC-1/28 Amdt 10","sortOrder":1},{"sectionNumber":"Undercarriage Mounting Casting","sectionType":"part","heading":"Undercarriage Mounting Casting","content":"## Undercarriage Mounting Casting","sortOrder":2},{"sectionNumber":"13/2011","sectionType":"part","heading":"13/2011","content":"## 13/2011","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":3,"scope_assessment":{"changed":true,"description":"The original directive (effective 1979) applied only to English-produced Chipmunks. This amendment expands the scope to include Portuguese-manufactured T Mk 20 models, which were previously excluded. However, the core safety purpose — preventing undercarriage mounting casting failures — remains unchanged. The expansion reflects new evidence that the Portuguese models share the same design vulnerability."},"complexity_factors":["Short, single-purpose directive focused on one specific mechanical component","Only 4 substantive sections (Applicability, Requirement, Compliance, Background)","Single cross-reference to UK CAA AD 2807 and one technical document (British Aerospace Technical News Sheet)","One conditional exemption (Mod H.310) requiring owner verification with manufacturer","Minimal defined terms — relies on external technical documentation for detailed inspection procedures","Clear compliance pathway: prior compliance with Amendment 8 satisfies this amendment"],"plain_english_summary":"This AD mandates repetitive inspections of the main undercarriage leg mounting castings on De Havilland DHC-1 Chipmunk aeroplanes (English C1 models and, newly included, Portuguese T Mk 20s) for stress‑corrosion cracking, following British Aerospace Technical News Sheet CT (C1) No. 165 Issue 7. \n\nCracking is driven mainly by calendar age and can cause landing‑gear collapse; wings modified by De Havilland Mod H.310 may be exempt but owners should verify with the manufacturer."},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"This amendment expands applicability by adding Portuguese-manufactured DHC-1 (T Mk 20) to the aircraft subject to the inspection requirement. The substantive inspection requirements, intervals and compliance regime remain unchanged from the prior amendment (Requirement/Background)."},"complexity_factors":["Technical subject-matter: fatigue/stress-corrosion cracking in undercarriage casting (Background)","External-document reliance: mandates inspections per British Aerospace Technical News Sheet CT (C1) No.165 Issue 7 or later (Requirement)","Cross-jurisdictional reference: UK CAA approval and UK CAA AD 2807 cited (Requirement/Background)","Applicability nuance: specific to English production (C1) and newly-added Portuguese T Mk 20 models (Applicability/Background)","Variable inspection regime: intervals and limits set in external document rather than fully prescribed in the AD (Requirement/Compliance)","Operational burden: possible need to defuel aircraft before inspection (noted in amendment history / Requirement)","Administrative history: multiple prior amendments and credit for prior compliance (Compliance/Background)","Implementation ambiguity: operators may need to consult the type certificate (TC) holder if unsure about modification status (Requirement)"],"plain_english_summary":"Requires periodic inspection of the main undercarriage leg mounting castings on English-built DHC‑1 (C1) and Portuguese T Mk 20 Chipmunks, performed to British Aerospace Technical News Sheet CT (C1) No.165 Issue 7 or a later UK CAA‑approved revision. Owners/operators must follow the inspection intervals and limits in that document. \n\nThe AD addresses calendar-time stress‑corrosion cracking; inspection, any defuelling for inspection, and any repairs are obligations of the aircraft owner/operator and are enforced by CASA."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-1-28-amdt-10-undercarriage-mounting-casting","history":"/api/acts/ad-dhc-1-28-amdt-10-undercarriage-mounting-casting/history","analysis":"/api/acts/ad-dhc-1-28-amdt-10-undercarriage-mounting-casting/analysis","conflicts":"/api/acts/ad-dhc-1-28-amdt-10-undercarriage-mounting-casting/conflicts","importantCases":"/api/acts/ad-dhc-1-28-amdt-10-undercarriage-mounting-casting/important-cases","documents":"/api/acts/ad-dhc-1-28-amdt-10-undercarriage-mounting-casting/documents"}}