{"id":"F2011L01087","name":"AD/DHC-1/34 Amdt 2 - Shock Absorber Strut Piston Tube","slug":"ad-dhc-1-34-amdt-2-shock-absorber-strut-piston-tube","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":86885,"registerId":"commonwealth-F2011L01087-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-1/34 Amdt 2 | Shock Absorber Strut Piston Tube | 12/2011 |\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 (TNS) No.194 Issue 2.Note 1: TNS 194 provides details of BAe field support with regard to sample collection or chemical analysis services etc. to comply with the requirements of this Directive. Local NATA testing laboratories are also able to carry out the chemical analysis requirement. A copy of BS T60 is available on request to the Authority through a District Airworthiness Office.Note 2: UK CAA AD 004-02-95 refers.                                                                                                                                                                                                                                                                                                                                                |\n| Compliance:    | Unless already accomplished, before further flight.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |\n|                | This Amendment becomes effective on 21 June 2011.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |\n| Background:    | A case has been found of an unapproved main undercarriage piston tube of unknown origin being fitted to an aircraft. The item was of incorrect material and gauge.This inspection was introduced in 1995, and up until now, Australia has had no Portuguese manufactured Chipmunks on the register, hence the CASA AD has only been effective for English production Chipmunks.This amendment is to include the Portuguese manufactured Chipmunk in the applicability for this AD, as a recent review shows that this inspection is also applicable to the Portuguese model (T Mk 20).There is no change to the requirements. The TNS specifies compliance within 12 months of the issue date of the TNS. Since this date is well past, all aircraft (including recently imported or about to be imported aircraft) must comply before further flight. |\n\n|     | Amendment 1 was issued in 1997 in response to a new UK CAA AD which requires certain actions because cases have been found of undercarriage piston tubes being manufactured from material of incorrect specification. Piston tubes have also been found to have suffered from corrosion, both internally and externally. |\n| --- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n\n![](image.001.png)  \nGlen Steemson  \nDelegate of the Civil Aviation Safety Authority\n\n15 June 2011","sortOrder":0},{"sectionNumber":"AD/DHC-1/34 Amdt 2","sectionType":"part","heading":"AD/DHC-1/34 Amdt 2","content":"## AD/DHC-1/34 Amdt 2","sortOrder":1},{"sectionNumber":"Shock Absorber Strut Piston Tube","sectionType":"part","heading":"Shock Absorber Strut Piston Tube","content":"## Shock Absorber Strut Piston Tube","sortOrder":2},{"sectionNumber":"12/2011","sectionType":"part","heading":"12/2011","content":"## 12/2011","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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The amendment expands applicability: it adds Portuguese‑manufactured DHC‑1 (T Mk 20) aircraft to the set of affected Chipmunks. The technical inspection requirement itself is unchanged, but because the TNS's original 12‑month compliance window has passed, all affected aircraft (including recent or incoming imports) must now comply before further flight."},"complexity_factors":["Single, focused mandatory action: inspection of piston tube per BAe TNS No.194 Issue 2 (low procedural complexity)","Cross‑references to external technical material (BAe TNS No.194, BS T60, UK CAA AD 004‑02‑95) requiring access to non‑statutory documents","Possible requirement for chemical analysis and sample collection, involving third‑party labs (NATA) or BAe field support (adds logistical and cost elements)","Applicability expansion to include Portuguese production (T Mk 20) increases population of affected aircraft and administrative tracking","Compliance timing nuance: original TNS set a 12‑month window that has lapsed, so CASA requires compliance before further flight (creates immediate grounding risk if non‑compliant)","No change to technical requirements from prior amendment, limiting regulatory complexity but requiring historical record checks for prior compliance"],"plain_english_summary":"This amendment expands an existing airworthiness directive to cover Portuguese‑built De Havilland DHC‑1 Chipmunks (T Mk 20) and requires inspection of the main undercarriage piston tube in accordance with British Aerospace Technical News Sheet No.194 Issue 2. Owners/operators must complete the inspection (which may include sample collection and chemical analysis using BAe support or local NATA labs) before further flight if not already done. The action responds to findings of incorrect material and corrosion and places the inspection cost and any repair/replacement decisions on aircraft operators."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"The original 1995 directive only applied to English production Chipmunks. This amendment expands the scope to include Portuguese-manufactured T Mk 20 models, reflecting the changed Australian aircraft register (new imports). However, the core safety requirement remains unchanged — the expansion is geographic/model coverage rather than substantive mission creep."},"complexity_factors":["Short, single-purpose directive focused on one mechanical component","Only 2 defined/referenced documents (TNS No.194 Issue 2, BS T60)","Simple conditional logic: 'Unless already accomplished, before further flight'","Clear applicability table limiting scope to specific production models","Cross-reference to UK CAA AD 004-02-95 for background context only","No nested exceptions or layered conditional requirements","Background narrative explains rationale in plain language rather than dense legal text"],"plain_english_summary":"This Airworthiness Directive mandates immediate inspection of the De Havilland DHC‑1 Chipmunk main landing‑gear shock absorber piston tubes to verify correct material, thickness and absence of corrosion. It now covers English and Portuguese (T Mk 20) Chipmunks and must be complied with before further flight using the procedures in British Aerospace Technical News Sheet No.194 — a safety measure to prevent landing‑gear failures."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-1-34-amdt-2-shock-absorber-strut-piston-tube","history":"/api/acts/ad-dhc-1-34-amdt-2-shock-absorber-strut-piston-tube/history","analysis":"/api/acts/ad-dhc-1-34-amdt-2-shock-absorber-strut-piston-tube/analysis","conflicts":"/api/acts/ad-dhc-1-34-amdt-2-shock-absorber-strut-piston-tube/conflicts","importantCases":"/api/acts/ad-dhc-1-34-amdt-2-shock-absorber-strut-piston-tube/important-cases","documents":"/api/acts/ad-dhc-1-34-amdt-2-shock-absorber-strut-piston-tube/documents"}}